Hypoallergenic Diets in Dogs and Cats: 2026 Update

Food allergy affects up to 33% of atopic dogs and 22% of pruritic cats. As of 2026, the elimination diet remains the only validated diagnostic tool for confirming food allergy, as no serological or salivary test can confirm it. Discover in this comprehensive article the immunopathological mechanisms and current diagnostic strategies, from choosing hypoallergenic food to long-term management. Grain-free or insect-based diets, the specific features of these diets in cats, the role of the provocation test, and more. We cover it all.

PART I — NOSOLOGICAL FRAMEWORK AND EPIDEMIOLOGY

Chapter 1 — Definitions and Classification of Adverse Food Reactions

1.1 — Adverse Food Reaction (AFR): General Nosological Framework

The term adverse food reaction (AFR) constitutes a nosological framework encompassing all abnormal clinical responses following the ingestion of a food or food additive. This definition, adopted by international consensus, encompasses heterogeneous pathophysiological mechanisms distinguished by the nature of the biological response involved (Gaschen 2011). AFRs are subdivided into two main categories: immunological reactions (true food allergies) and non-immunological reactions (food intolerances, food poisoning, pharmacological reactions to biogenic amines). The exact prevalence of AFRs remains difficult to establish precisely, due to the variability of diagnostic criteria used across studies and the low owner compliance with provocation challenge protocols. Data compiled by Olivry and Mueller (2017) indicate that 1 to 2% of dogs presented in general practice are affected, a figure that rises to 9 to 40% among pruritic dogs (median: 18%) and 9 to 50% (median: 29%) in dogs displaying a clinical phenotype of atopic dermatitis. In cats, prevalence among animals presenting cutaneous signs ranges from 0.22 to 6% depending on the populations studied (Olivry 2017).

1.2 — True Food Allergy vs. Food Intolerance

True food allergy is defined by a specific immunological response directed against one or more dietary proteins, involving the adaptive immune system. This response may be mediated by immunoglobulin E (IgE) via type I hypersensitivity according to the Gell and Coombs classification (Pucheu-Haston 2020), or by T lymphocytes via type IV hypersensitivity (Jackson 2023). Food intolerance, by contrast, does not involve the adaptive immune system. It results from non-immunological mechanisms such as enzymatic deficiencies (lactase deficiency), pharmacological reactions to biogenic amines (histamine, tyramine found in certain fermented products), or direct toxic effects (Mueller 2018). The distinction between these two entities is of major clinical importance: true allergy generates reactions reproducible at sometimes minute doses of the allergen, whereas intolerance is often dose-dependent. In clinical veterinary practice, however, this distinction remains difficult to establish without a standardized provocation challenge, as cutaneous and digestive manifestations are often indistinguishable.

1.3 — Cutaneous Adverse Food Reaction (CAFR): Definition and International Terminology

The term CAFR designates specifically the dermatological manifestations secondary to the ingestion of a food (Olivry 2019). This terminology has been updated to harmonize nomenclature across different publications. CAFR is distinguished from environmental atopic dermatitis (EAD) by its dietary etiology, although both entities share a comparable clinical phenotype — notably non-seasonal pruritus affecting the extremities, ear pinnae, and flexural areas. In dogs, 94% of CAFR cases manifest with pruritus as the dominant sign (Olivry 2019). In cats, the term Feline Atopic Syndrome (FAS) also encompasses feline EAD, reflecting the difficulty of dissociating them without a food elimination diet.

Labial lesions are frequently present in food allergy

1.4 — IgE-Mediated and Non-IgE-Mediated Mechanisms

The immunopathological mechanisms underlying canine and feline food allergies involve two main pathways. The IgE-mediated pathway (type I) relies on the production of specific IgE directed against dietary glycoproteins with a molecular weight between 10 and 70 kDa (Cave 2006). Upon re-exposure, these IgE bound to FcεRI receptors on tissue mast cells trigger mast cell degranulation and release of histamine, leukotrienes, and prostaglandins, causing erythema, pruritus, and localized edema. The T-cell pathway (type IV), non-IgE-mediated, involves helper T lymphocytes (Th1 and Th2) and manifests in a delayed manner, between 24 and 72 hours after ingestion. In vitro data (Masuda 2020) indicate that enzymatic hydrolysis, even generating peptides of very low molecular weight (1 to 3.5 kDa), does not completely suppress the epitopes recognized by T lymphocytes. Lymphocyte activation was detected in approximately 28.8% of tested dogs. However, this cellular recognition remains overwhelmingly below the threshold of clinical reactivity (only approximately 2% of patients reach the lymphocyte activation threshold of 1.2% correlated with symptoms). Consequently, high-quality hydrolyzed diets retain remarkable clinical efficacy in vivo and represent an option of choice for the elimination diet, although very rare residual T-lymphocyte-mediated reactivity (type IV) may explain certain refractory failures. This finding underscores that protein hydrolysis, even extensive, does not completely suppress the T-cell immunogenic potential of dietary proteins.

Chapter 2 — Epidemiology and Prevalence of CAFRs

2.1 — Prevalence in the General Population and Among Pruritic Dogs

Epidemiological data compiled in the series of Critically Appraised Topics published by Olivry and Mueller between 2015 and 2020 provide the current reference framework. The prevalence of CAFRs in the general canine population ranges from 1 to 2% (Olivry 2017). This figure increases significantly when considering selected populations: among dogs presenting chronic pruritus, the median prevalence reaches 18% (range: 9 to 40%), and among those with allergic dermatitis, it rises to 29% (range: 9 to 50%). In cats, data are less abundant but converge toward a prevalence of 12 to 22% among subjects presenting allergic cutaneous signs and 0.22 to 6% in the general population. These figures justify the systematic integration of the exclusion diet in the workup of any non-seasonal pruritus in companion animals.

2.2 — Bimodal Distribution of Age of Onset

The age of onset of CAFRs shows a bimodal distribution. The first age group corresponds to young dogs under one year of age: 38% of cases occur before 12 months of age and 22% before 6 months of age (Olivry 2019). The mean age of onset is 2.9 years (range: 1 to 13 years), with a second peak in dogs over 7 years of age. In puppies, this characteristic makes it necessary to consider food allergy from the first manifestations of pruritus, even before considering environmental sensitization, which typically develops progressively. In cats, the age of onset is more variable, with cases reported from 3 months to 11 years. The bimodal distribution in dogs suggests two distinct sensitization windows: one early, linked to the immaturity of the intestinal barrier and gut-associated lymphoid tissue (GALT), and another late, possibly related to an acquired breakdown of oral tolerance.

2.3 — Breed Predispositions

Several breeds show overrepresentation in studies on CAFRs. In dogs, the West Highland White Terrier (WHWT) stands out with a clinical phenotype marked by generalized pruritus, severe facial erythema, and recurrent pyoderma localized to the ventral trunk and limbs. The Labrador Retriever and Golden Retriever develop chronic bilateral pododermatitis, recurrent ceruminous otitis, and interdigital erythema that progressively extends to the flexural areas. Their response to elimination diets is generally satisfactory, with notable clinical improvement between 4 and 6 weeks. The Boxer presents a cutaneous profile dominated by periocular and perioral erythema, with a frequent digestive component (flatulence, soft stools). The German Shepherd is characterized by severe perineal and ventral involvement, often complicated by deep pyoderma. The Cocker Spaniel develops chronic proliferative external otitis, with secondary Malassezia dermatitis resistant to topical treatments. In cats, the Siamese breed shows a predisposition with a predominantly facial and cervical clinical expression (Olivry 2019). Unlike Labrador ichthyosis (PNPLA1 mutation), no specific susceptibility gene for CAFRs has been identified to date, which constitutes a major gap in understanding the genetic determinism of this condition.

 

2.4 — Co-Sensitization and Polyallergenicity

Food and environmental co-sensitization represents a frequent clinical reality. A significant proportion of dogs with environmental atopic dermatitis (EAD) simultaneously present a CAFR: estimates range from 13 to 33% depending on the study (Jackson 2023). This pathological concurrence complicates the diagnostic approach, as partial improvement under an elimination diet may be masked by the persistence of pruritus related to the environmental component. Concurrent gastrointestinal disorders (diarrhea, vomiting, increased defecation frequency) are reported in 20 to 30% of dogs and cats with CAFR (Mueller 2018). In dogs, animals with an AFR present primarily diarrhea, 2% isolated vomiting, and 5% both signs combined. In cats, the proportion of vomiting (38%) is higher than in dogs, reflecting more frequent involvement of the upper digestive tract and stomach (Mueller 2018).

2.5 — Epidemiological Data: Emerging Trends and New Studies

Recent data confirm an apparent trend toward increasing prevalence of CAFRs, likely multifactorial. The multicenter prospective study by Lewis et al., involving 57 pruritic dogs, reports a CAFR diagnosis rate of 44.7% (21/47 dogs completing the study), a figure higher than historical data (This rate, higher than historical data, must be interpreted in the context of a highly selected patient population referred for suspected allergic dermatitis, which introduces a major selection bias (Lewis TP 2025). It cannot be directly extrapolated to the general canine population). This increase could reflect improved diagnostic protocols, greater practitioner awareness, or a real modification of allergen exposure linked to changes in commercial food formulas. The diversification of protein sources in companion animal foods (increasing use of exotic animal proteins, insects, legumes) modifies the antigenic exposure profile and could explain the emergence of new sensitizations (Villaverde 2024).

PART II — IMMUNOPATHOLOGY AND ALLERGENS

Chapter 3 — Immunopathological Basis of Food Reactions

3.1 — Oral Tolerance and GALT

Oral tolerance relies on CD103+ dendritic cells of the intestinal lamina propria, which capture luminal antigens (through epithelial junctions, and via macrophages extending transepithelial projections) and migrate to mesenteric lymph nodes (Jackson 2023). In these nodes, they induce the differentiation of naive T lymphocytes into regulatory T lymphocytes (Tregs) expressing the transcription factor FoxP3. These Tregs secrete immunosuppressive cytokines — primarily IL-10 and TGF-β — which maintain a state of non-reactivity toward dietary antigens. The stability of this mechanism depends on the integrity of the intestinal epithelial barrier, the composition of the gut microbiome, and the maturation of the digestive system. In puppies, the immaturity of GALT (Gut-Associated Lymphoid Tissue) and increased intestinal permeability create a window of vulnerability that explains the frequency of early sensitizations.

3.2 — Breakdown of Tolerance

Among the proposed mechanisms for the breakdown of oral tolerance is the release of TSLP by damaged enterocytes, well documented in human medicine and in mice. Direct data in dogs and cats are still limited in the literature, and this pathway is currently extrapolated from human models of food allergy.

3.3 — IgE Isotype Class Switching

Isotype class switching toward IgE represents the critical step in allergic sensitization. Under the influence of IL-4 and IL-13 produced by Th2 lymphocytes, B lymphocytes undergo genetic recombination at the switch Sε region of the immunoglobulin heavy chain gene, leading to the production of IgE specific to the dietary allergen. These IgE then bind to high-affinity FcεRI receptors expressed on the surface of cutaneous and intestinal tissue mast cells. This overexpression lowers the mast cell degranulation threshold and explains clinical hypersensitivity to low doses of allergens. Upon re-exposure, simultaneous cross-linking of two adjacent membrane-bound IgE molecules by a multivalent allergen triggers the degranulation cascade, releasing histamine, tryptase, and prostaglandins, responsible for the characteristic pruritus, erythema, and edema.

3.4 — Non-IgE-Mediated T-Cell Mechanism

The T-cell component of CAFRs constitutes a rapidly expanding research axis. Lymphocyte blastogenesis studies conducted by Fujimura et al. demonstrated significant T lymphocyte proliferation in response to food allergens in dogs with confirmed CAFR (Fujimura 2011). Masuda et al. refined these results using flow cytometry to analyze peripheral blood mononuclear cells (PBMCs) from 316 dogs suspected of food allergy (Masuda 2020). Results showed that hydrolyzed diet extracts contained proteins or peptides with molecular weights between 1 and 3.5 kDa, capable of stimulating CD25low helper T lymphocytes. The rate of positive lymphocyte response to hydrolyzed extracts reached 28.8% (91/316 samples) for the first tested diet and 23.7% (75/316) for the second. Among the 186 samples also reactive to avian antigens, these rates rose to 38.7% and 29.6% respectively. However, it is incorrect to conclude that hydrolyzed diets have a failure rate of nearly 30% linked to T-cell stimulation. Indeed, this activation only reaches the threshold of clinical relevance (capable of triggering a dermatological relapse in vivo) in approximately 2% of cases. The risk of clinical failure due to T-lymphocyte stimulation is therefore very low and primarily limited to animals already presenting severe cellular hypersensitivity to the protein source of the hydrolysate (e.g., feather hydrolysate in a dog highly allergic to chicken). Extensively hydrolyzed diets therefore remain a highly reliable first-line diagnostic tool.

3.5 — Cross-Reactivities

Cross-reactivities between food allergens represent a major clinical challenge for the selection of novel protein elimination diets. Bexley et al. demonstrated by ELISA significant IgE cross-reactivity between chicken and fish proteins in dogs (Bexley 2019): among canine sera presenting elevated anti-chicken IgE, 97% also reacted with turkey and duck extracts (Olivry 2017). The study by Olivry et al. on 40 canine and 40 feline sera showed that anti-chicken IgE recognized turkey meat (97% of dogs, 84% of cats) and duck meat (97% of dogs, 97% of cats), confirming extensive cross-reactivity within the Galliformes family (Olivry 2017). Beef-lamb cross-reactivity, linked to conserved epitopes among proteins of the Ruminantia (notably bovine serum albumin Bos d 6 and its ovine homologues), is documented less systematically but must be anticipated when selecting an alternative protein source. However, its actual clinical incidence in canine and feline CAFRs remains insufficiently documented in the veterinary literature to precisely quantify the risk. The pollen-food syndrome, well described in human medicine, is suspected in atopic dogs sensitized to certain grass pollens cross-reacting with cereal proteins (wheat, corn).

Chapter 4 — Main Food Allergens According to Studies

4.1 — Mueller et al. 2016 Systematic Review (1985–2015): Methodology and Results

The systematic review published by Mueller, Olivry, and Prélaud (2016) constitutes the methodological reference for identifying food allergens in veterinary medicine. This analysis compiled data from 297 dogs and 78 cats whose CAFR diagnosis had been confirmed by elimination diet followed by individual provocation challenges between 1985 and 2015. The methodology relied on strict inclusion criteria: only studies reporting clinical improvement under an exclusion diet followed by documented recurrence upon reintroduction of the incriminated food were retained. Challenges had to be performed with individual ingredients to allow specific identification of the responsible allergen. This methodological rigor explains the relatively limited number of subjects included despite the analysis period spanning 30 years.

4.2 — Main Allergens in Dogs: Beef (34%), Dairy Products (17%), Chicken (15%), Wheat (13%), Lamb (5%)

In dogs, the hierarchy of food allergens established by Mueller, Olivry, and Prélaud places beef in first position with 34% of positive reactions during provocation challenges, followed by dairy products (17%), chicken (15%), wheat (13%), and lamb (5%). Soy, corn, and egg each represent less than 5% of confirmed sensitizations. These data contradict the popular perception that cereals constitute the main canine food allergens: in reality, animal proteins (beef, dairy products, chicken, lamb) account for more than 70% of sensitizations. The high frequency of beef as an allergen reflects its near-ubiquitous presence in commercial kibble and food for dogs, confirming the correlation between prolonged dietary exposure and the risk of sensitization. Wheat, while less frequently implicated than animal proteins, represents the most allergenic carbohydrate source, with reactivity linked to the gliadins and glutenins contained in gluten.

4.3 — Main Allergens in Cats: Beef (18%), Fish (17%), Chicken (5%)

In cats, the allergen profile differs noticeably from that of dogs. Beef represents 18% of confirmed sensitizations, followed by fish (17%) and chicken (5%) (Mueller 2018). The position of fish in second place reflects the high proportion of fish proteins in commercial feline food, particularly in wet foods and recipes based on tuna, salmon, and white fish. Dairy products and wheat are reported in less than 5% of feline cases. Lamb and egg are among the minor allergens. However, data specific to cats remain limited by the small number of subjects who underwent individual provocation challenges in published studies (78 cats in the Mueller 2016 meta-analysis) and must be interpreted with caution. The emergence of new insect-based diets (Hermetia illucens, Tenebrio molitor) for the feline species could modify this profile in coming years, although allergenicity data for these protein sources are still limited.

4.4 — Molecular Characterization of Epitopes

Molecular characterization of food allergens by Component-Resolved Diagnostics (CRD) opens new perspectives for understanding sensitization mechanisms. Bovine serum albumin Bos d 6 (molecular weight: 67 kDa) constitutes one of the main beef allergens identified in dogs. Its conserved tertiary structure among mammals explains the cross-reactivities observed between beef, lamb, and venison. Ovomucoid Gal d 1 (28 kDa), the main allergen of hen’s egg, presents thermal and enzymatic resistance that maintains its allergenicity after cooking and gastric digestion. Parvalbumin (Gad m 1, ~11.5 kDa) represents a major allergen in fish, with conserved homologues in salmon, trout, and cod (Bexley 2019). Enolase (Gad m 2, ~47-50 kDa) is an additional allergen with a lower prevalence of sensitization. These molecular data allow anticipation of cross-reactivities when choosing a novel protein for the elimination diet and could, in time, improve the precision of in vitro diagnostic tests.

4.5 — Food Additives and Biogenic Amines

The role of food additives (colorants, preservatives, flavorings) and biogenic amines (histamine, tyramine, putrescine) in AFRs in dogs and cats remains marginal in the scientific literature. Available studies report only rare cases of reactions attributed to specific additives, and no robust evidence supports their frequent involvement in CAFRs (Mueller 2018). Biogenic amines, present in variable concentrations in fermented or poorly preserved foods, can provoke dose-dependent reactions (vasodilation, pruritus) through a direct pharmacological mechanism involving H1 and H2 histamine receptors, without involvement of the adaptive immune system. These reactions fall under food intolerance and not true allergy. The distinction is important in clinical practice, as these reactions do not recur during provocation challenges conducted with fresh ingredients of good quality.

4.6 — Comparative Table: Dog vs. Cat Allergens

The allergen profile of dogs and cats presents similarities (predominance of animal proteins, low involvement of cereals) but also notable differences. Beef dominates in both species, with 34% in dogs vs. 18% in cats. Fish holds second place in cats (17%) while remaining a minor allergen in dogs (<5%). Chicken represents 15% of canine sensitizations vs. 5% of feline sensitizations. Dairy products, frequent in dogs (17%), are rarely reported in cats. Wheat constitutes the third canine allergen (13%) but remains anecdotal in cats. These differences reflect species-specific dietary exposure profiles and the typical composition of commercial kibble and wet foods available in the US.

4.7 — New Protein Sources Implicated

The rapid evolution of the pet food market is modifying the antigenic exposure profile of dogs and cats. The democratization of diets based on duck, venison, kangaroo, and salmon in mass-market lines (OTC) is progressively reducing the repertoire of “novel” proteins for a given animal. Grain-free kibble based on legumes (peas, lentils) and potato, very popular since 2018, introduces new potential allergens whose incidence in CAFRs has not yet been systematically documented.

The question of the cardiovascular safety of these grain-free diets has also been raised since the alert published by the FDA in 2018, which recorded 1,100 reports — including 560 cases of dilated cardiomyopathy (DCM) — in dogs of breeds not normally predisposed (Golden Retriever, Labrador Retriever, Bulldog), in association with prolonged consumption of grain-free diets rich in legumes (Freeman 2018). Proposed mechanisms include a taurine deficiency linked to reduced bioavailability of lysine and methionine in formulas with high legume content, an interaction between plant lectins and the intestinal mucosa, and the presence of antinutritional compounds reducing absorption of sulfur-containing amino acids (Adin 2019). Although the 2022 FDA update clarified that causality had not been formally established, this vigilance is warranted when prescribing prolonged grain-free diets based on legumes, particularly in at-risk breeds such as Golden and Labrador Retrievers.

The increasing use of insect proteins (black soldier fly meal, Hermetia illucens; mealworm, Tenebrio molitor) in animal food formulas constitutes an emerging trend. The study by Majewski et al. (2021), published in Animals (Basel), demonstrated in atopic dogs the binding of canine serum IgE to proteins extracted from Tenebrio molitor, with identification of 17 allergenic proteins including tropomyosin, α-amylase, and the cuticular protein Tm-E1a — all three recognized as cross-reactive allergens with storage and house dust mites (Dermatophagoides farinae, Tyrophagus putrescentiae). Rodríguez-Pérez et al. complemented these data with an in silico mapping of B and T epitopes of tropomyosin, confirming the phylogenetic conservation of this molecule in all arthropods and the bidirectional nature of cross-reactivity: an animal sensitized to mites may react to insects, and vice versa (Rodríguez-Pérez 2024). These data call for caution in the use of insect-based diets in any dog or cat presenting documented sensitization to mites. In the absence of controlled provocation studies in canine and feline species, these diets should not be used as elimination diets in atopic animals sensitized to mites until this risk is clinically validated.

PART III — CLINICAL EXPRESSION

Chapter 5 — Clinical Manifestations in Dogs

5.1 — Non-Seasonal Pruritus

Non-seasonal pruritus constitutes the cardinal sign of CAFRs in dogs, reported in 94% of subjects in the systematic review by Olivry and Mueller (2019). This pruritus is characterized by its persistence throughout the year, independent of pollen seasons, unlike the pruritus of strictly environmental EAD, which shows marked seasonality in temperate regions. The intensity of pruritus, evaluated by the pruritus visual analog scale (PVAS, 0-10), typically ranges between 5 and 9 in dogs with untreated CAFR. The diagnostic value of the non-seasonal nature of pruritus is, however, relative: approximately 30% of atopic dogs sensitized to mites also present perennial pruritus. Therefore, the non-seasonal character points toward CAFR but does not confirm it. An incomplete clinical response to glucocorticoids is frequently reported in CAFRs and constitutes an indirect clinical indicator pointing toward a dietary component. However, no quantitative response threshold (such as 50%) has been validated by a controlled diagnostic study. This criterion must be interpreted in association with other clinical orientation elements (non-seasonal character, digestive signs, age of onset) and can in no way substitute for the elimination diet.

5.2 — Topographical Distribution

The topographical distribution of cutaneous lesions in canine CAFRs is superimposable on that of EAD, making clinical distinction impossible without an exclusion diet. Recurrent bilateral external otitis constitutes one of the most frequent manifestations of canine CAFRs, reported in 24 to 80% of cases depending on the study, with a median of approximately 50-60% (Olivry and Mueller, 2019). This sign is, however, also very frequent in environmental EAD and does not have sufficient diagnostic specificity to differentiate the two etiologies. Pedal involvement manifests as interdigital erythematous pododermatitis, with marked pruritus of the palmar and plantar interdigital spaces. The axillary, inguinal, and perineal regions present diffuse erythema with cutaneous thickening (lichenification) in chronic cases. The ventral abdomen and inner thighs, from the inguinal region to the inner hocks, are frequently affected. The coat may present brownish coloration due to chronic licking, visible in dogs with light-colored coats. The skin of the flexural areas (elbows, carpi, tarsi) shows hyperpigmentation and lichenification reflecting the chronicity of itching.

5.3 — Primary and Secondary Lesions

Primary lesions of canine CAFRs include erythema (diffuse or localized), papules, and, more rarely, urticaria. Erythema represents the earliest lesion, observable within the first hours after allergen exposure during provocation challenges. Papules, small in size (2-5 mm), are scattered over the ventral trunk and limbs. Secondary lesions result from self-trauma and opportunistic superinfections. Superficial pyoderma caused by Staphylococcus pseudintermedius constitutes a frequent complication of allergic dermatitis, including CAFRs, although the exact rate of occurrence specifically in CAFRs is not quantified distinctly in the literature. The high prevalence of these secondary superinfections requires their detection and treatment before and during the elimination diet. Malassezia dermatitis (proliferation of Malassezia pachydermatis) worsens pruritus and generates greasy, malodorous erythema, predominating in skin folds, ear canals, and interdigital spaces. These secondary superinfections must be treated before and during the diet, as their persistence may mask the clinical improvement linked to dietary allergen exclusion and simulate a diagnostic failure.

5.4 — Relative Glucocorticoid Resistance

Relative glucocorticoid resistance constitutes an indirect diagnostic indicator in favor of a dietary component. Dogs with CAFR present a significantly lower pruritus response to prednisone than that observed in strictly environmental EAD. Favrot et al. evaluated the usefulness of a short corticosteroid course (prednisolone, 0.5 mg/kg/day for 14 days) during the initial phase of an elimination diet trial in dogs with food-induced atopic dermatitis (Favrot 2019). Results show that adding a short corticosteroid course improves owner compliance by reducing pruritus during the first weeks, without compromising the interpretation of the elimination diet at its conclusion. Oclacitinib at a dose of 0.4-0.6 mg/kg orally twice daily for 14 days then once daily constitutes an alternative for pruritus control during the initial phase of the diet.

5.5 — Concurrent Gastrointestinal Manifestations

Gastrointestinal manifestations associated with canine CAFRs are reported in 20 to 30% of subjects (Mueller 2018). Among these dogs, diarrhea is the predominant manifestation, often associated with vomiting, but isolated vomiting is rarely observed (Mueller and Olivry, 2018). The most frequent signs include increased defecation frequency (>3 bowel movements per day), chronic small or large bowel diarrhea, borborygmi, flatulence, and, more rarely, vomiting. The use of second-generation diets based on ultra-hydrolyzed proteins shows remarkable efficacy in cases of refractory chronic canine enteropathies, but requires prolonged compliance. A pilot study (Freiche 2025) demonstrated that the clinical remission rate, initially 61.5% after 5 weeks, increases significantly to exceed 90% after 10 weeks of strict diet. This slow kinetics highlights the importance of maintaining gastrointestinal dietary trials for a minimum of 8 to 10 weeks before concluding therapeutic failure. Rodrigues et al. confirmed in a multicenter retrospective study the association between the type of diet used and the therapeutic response in dogs with chronic enteropathy, underscoring the importance of food choice in overall management. Evaluation of the digestive system by coprology, and where appropriate by endoscopy with intestinal biopsies, remains recommended in cases of predominant or resistant digestive signs (Rodrigues 2025).

Chapter 6 — Clinical Manifestations in Cats

6.1 — Feline Atopic Syndrome (FAS): Definition and Place of CAFRs

Feline Atopic Syndrome (FAS) encompasses all allergic dermatitis in cats, whether of dietary origin (CAFR) or environmental origin (feline EAD). This classification, proposed by Hobi et al. (Hobi 2011) and adopted in the international consensus, reflects the clinical impossibility of distinguishing these two etiologies without an exclusion diet. CAFRs represent a significant proportion of FAS: 12 to 22% of pruritic cats show clinical improvement under an elimination diet confirmed by provocation challenge (Olivry 2017). FAS is characterized by a clinical polymorphism specific to the feline species, with four main cutaneous patterns that may coexist in the same subject.

6.2 — Clinical Patterns

The clinical expression of FAS of dietary origin follows the four classic cutaneous patterns of feline allergy. The eosinophilic granuloma complex includes the eosinophilic plaque (erythematous, raised, erosive plaque, localized to the inner thighs and ventral abdomen), the indolent ulcer (upper labial ulcer, non-painful, oval-shaped), and linear granuloma (firm, linear nodule, localized to the caudal surface of the thighs). Miliary dermatitis, characterized by multiple papulo-crusts disseminated over the dorsal trunk and neck, represents the most frequent pattern. Self-induced alopecia, long described as “psychogenic,” actually results from discrete pruritus and compulsive licking; it predominates on the ventral abdomen and inner thighs, generating bilateral symmetrical alopecia without visible cutaneous lesions. Silva et al. reported the benefit of a hypoallergenic diet in controlling eosinophilic oral lesions in cats, confirming the link between CAFR and oral eosinophilic complex (Silva 2024).

6.3 — Facial and Cervical Pruritus

Facial and cervical pruritus constitutes a suggestive, though not pathognomonic, clinical presentation of CAFR in cats. Facial excoriations, localized to periocular, temporal, and pretragic regions, are often severe and lead to deep erosions with serosanguineous crusts. Dorsal cervical pruritus (dorsal surface of the neck and base of the ears) generates linear self-traumatic lesions (scratch-like excoriations) that may be confused with ectoparasitosis. The combination of facial pruritus + cervical pruritus + miliary dermatitis should primarily raise suspicion of CAFR and justifies implementing an elimination diet after excluding ectoparasites. The severity of facial pruritus has a direct impact on the well-being and quality of life of the cat, justifying the use of an antipruritic treatment during the initial phase of the diet.

6.4 — Extra-Cutaneous Manifestations

Extra-cutaneous manifestations of feline CAFRs include digestive signs (vomiting in 38% of cases, diarrhea in 45%, both combined in 18%; Mueller 2018), bilateral conjunctivitis, chronic rhinitis, and, more rarely, respiratory signs (sneezing, wheezing). The high proportion of vomiting in cats (38% vs. 2% in dogs) reflects more frequent involvement of the upper digestive tract and stomach. Allergic conjunctivitis, characterized by bilateral chemosis and serous discharge, is reported in approximately 10% of FAS cases of dietary origin. Hyperactive behavior and increased vocalization frequency have been described anecdotally in certain studies.

6.5 — Semiological Differences Between Dogs and Cats

The semiological differences between the two species are fundamental for guiding the diagnostic approach. In dogs, pruritus is the dominant sign in 94% of cases, with a characteristic pedal, auricular, and inguinal topography. In cats, cutaneous expression is more polymorphic, with a predominance of facial and cervical pruritus, and the absence of significant pododermatitis. Recurrent external otitis, frequent in dogs (50-80%), is rare in cats (<10%). Digestive signs, present in 20-30% of dogs, reach 40-50% of cats. Glucocorticoid resistance, indicative of a dietary component in dogs, is less well documented in cats. The optimal duration of the elimination diet is comparable in both species (minimum 8 weeks), but practical constraints differ considerably due to feline dietary neophobia and the risk of hepatic lipidosis.

PART IV — DIAGNOSTIC APPROACH AND ROLE IN THE ATOPIC WORKUP

Chapter 7 — Differential Diagnosis

7.1 — Diagnostic Algorithm for Chronic Non-Seasonal Pruritus

The workup of chronic non-seasonal pruritus in dogs and cats follows a sequential algorithm whose rigor determines the reliability of the final diagnosis. The first step consists of excluding ectoparasitoses (sarcoptic mange, demodicosis, cheyletiellosis, flea allergy) by a systematic empirical antiparasitic treatment for 6 to 8 weeks. The second step addresses the treatment of bacterial and fungal cutaneous superinfections that maintain pruritus independently of the primary etiology. The third step, once ectoparasitoses and superinfections have been excluded or controlled, corresponds to the workup of atopic dermatitis, of which CAFR represents an essential component. The elimination diet fits within this third step and should be performed before or during the environmental allergological workup (intradermal tests or serum IgE tests).

7.2 — Position of the Exclusion Diet in the Atopic Workup

The question of the sequence between the elimination diet and environmental allergological tests is debated in the veterinary dermatological community. Two approaches coexist. The sequential approach recommends performing the elimination diet first, in order to quantify the dietary component of pruritus before any environmental workup. The parallel approach proposes conducting the exclusion diet and intradermal/serum tests simultaneously, which reduces the overall duration of the workup but complicates interpretation of results. Hensel et al. proposed clinical criteria to guide the indication for the exclusion diet: non-seasonal pruritus, age of onset under 1 year or over 7 years, recurrent otitis, partial resistance to glucocorticoids, and the presence of concurrent digestive signs. The presence of two or more of these criteria increases the pre-test probability of CAFR and justifies prioritizing the elimination diet (Hensel 2015).

7.3 — Hensel Criteria for Indicating the Exclusion Diet

The criteria published by Hensel et al. provide a structured decision-making framework for indicating the elimination diet in the workup of chronic pruritus. These criteria take into account the non-seasonal character of pruritus (sensitivity: 82%), the topographical distribution of lesions (perianal involvement, bilateral auricular involvement), glucocorticoid resistance, the presence of concurrent gastrointestinal disorders, and age of onset (<6 months or >6 years). The combination of these criteria does not replace the elimination diet but improves the selection of cases most likely to benefit from this approach. The clinical criteria proposed by Favrot et al. and the recommendations of Hensel et al. (Hensel 2015) provide a framework for diagnosing canine atopic dermatitis, but do not constitute specifically validated criteria for predicting the probability of a CAFR. Several clinical elements — non-seasonal pruritus, early (<1 year) or late (>7 years) age of onset, recurrent otitis, concurrent digestive signs, suboptimal response to glucocorticoids — clinically point toward a dietary component and justify implementing an elimination diet, but their specific predictive value for CAFR has not been formally calculated.

7.4 — Critique of Diagnostic Tests

Alternative tests to the elimination diet (food serum IgE tests, salivary tests, hair tests, food intradermal tests) do not possess the reliability needed to diagnose CAFRs (Mueller 2017). The study by Coyner and Schick demonstrated that hair and saliva tests cannot differentiate atopic dogs from healthy subjects (Coyner 2019). Lam et al. confirmed the absence of clinical correlation of food serum IgE and IgG tests in dogs without confirmed allergic reactions (Lam 2019). Vovk et al. evaluated the accuracy of commercially available food serological tests in 2024 and conclude that specificity and sensitivity are insufficient to justify their diagnostic use (Vovk 2024). The information provided by these tests may mislead the practitioner and owner, leading to unfounded dietary exclusions or, conversely, a false sense of security.

7.5 — “Why Are Food Blood Tests Unreliable?”

The detection of allergen-specific serum IgE indicates only immunological sensitization, not clinical reactivity. A dog or cat may present high IgE titers directed against beef or chicken without manifesting any cutaneous or digestive reaction upon ingestion of these proteins. This phenomenon, termed clinically silent sensitization, is frequent and reflects oral tolerance maintained despite the presence of circulating IgE. Conversely, T-cell reactions (type IV) completely escape detection by serum IgE tests. Food serological tests (IgE and IgG) present a high rate of false positives, with significant overlap of results between healthy dogs and dogs with confirmed CAFR. This rate varies depending on the commercial platform, the type of immunoglobulin measured, and the allergen tested. All available data (Mueller 2017, Lam et al. 2019, Vovk et al. 2024) converge toward the conclusion that these tests do not possess the reliability needed to confirm or exclude a CAFR diagnosis. The elimination diet followed by provocation challenge remains the only diagnostic tool validated by scientific evidence.

7.6 — The Exclusion Diet (EDT): The Only Validated Gold Standard

The Elimination Diet Trial (EDT), followed by a provocation challenge, constitutes the only validated diagnostic tool for confirming CAFRs in dogs and cats (Olivry 2015, Mueller 2018, Jackson 2023, Villaverde 2024). The principle relies on the exclusive administration, for a minimum duration of 8 weeks, of a food containing no protein to which the animal has previously been exposed, or containing hydrolyzed proteins of sufficiently low molecular weight to not trigger an immune reaction. Clinical improvement (pruritus reduction ≥50%, decrease in CADESI-04) followed by recurrence of signs upon reintroduction of the former food confirms the diagnosis. The absence of a provocation challenge allows only a presumptive diagnosis, as improvement under the diet may result from non-specific effects (modification of intestinal flora, reduction of biogenic amines, improved digestion).

PART V — ELIMINATION DIETS: PRINCIPLES AND DETAILED IMPLEMENTATION

Chapter 8 — General Principles of Dietary Exclusion

8.1 — Fundamental Principle: Food Containing No Possible Sensitization Antigens

The fundamental principle of dietary exclusion rests on the complete elimination of any antigen capable of having induced immune sensitization in the animal. This elimination must be absolute: the slightest exposure, even in minute quantities, may be sufficient to maintain the immune response and mask the expected clinical improvement. The diet must contain exclusively protein and carbohydrate sources to which the animal has never been exposed (novel protein) or whose allergenic potential has been reduced by enzymatic hydrolysis below the IgE reactivity threshold (<5 kDa according to Cave 2006).

8.2 — Exhaustive Collection of Dietary History

The exhaustive collection of dietary history constitutes the first operational step of the elimination diet. This history must inventory all commercial foods (all brands and lines of kibble and wet food consumed since birth), treats (chew products, bones, rewards), table scraps, dietary supplements (omega-3, vitamins, fatty acids), flavored medications (palatable tablets containing chicken or beef animal proteins as excipients), and topicals liable to be licked (toothpastes, balms). Detailed analysis of the composition of each food (ingredient list on the label) allows establishing the list of proteins to which the animal has been exposed and guides the choice of a “novel” protein source.

8.3 — Owner Education: The Primary Cause of Failure = Non-Compliance

Owner non-compliance represents the most frequently documented cause of elimination diet failure. Sources of protocol deviation include administration of unauthorized treats, access to food of other household animals, persistence of flavored medications, and feeding by third parties (children, neighbors, pet sitters). Owner education must be conducted in a structured manner, with provision of a written document detailing the rules of the diet and the comprehensive list of prohibited items. A telephone follow-up at 2 weeks and a control appointment at 4 weeks are recommended to verify compliance and encourage continuation of the protocol.

8.4 — Involvement of the Entire Household

All persons in contact with the animal — family members, children, caregivers, dog-sitters, neighbors liable to offer treats — must be informed of the elimination diet rules. Dogs living outdoors or with garden access must be monitored to prevent ingestion of waste, other animals’ feces, or accessible food. In cases of cohabitation with other animals, food bowls must be separated and meals supervised. The cat’s food must be placed out of reach of the dog, and vice versa.

8.5 — The Three Main Categories of Available Diets

Three main categories of elimination diets are available in clinical veterinary practice in 2026. Novel Protein Diets use a protein source to which the animal has never been exposed (rabbit, venison, kangaroo, duck, trout, goat). Hydrolyzed protein diets contain proteins whose molecular weight has been reduced by enzymatic hydrolysis, theoretically below the IgE reactivity threshold. Elemental diets based on free amino acids constitute the most hypoallergenic form, devoid of any peptide capable of provoking an immune reaction. The choice between these options depends on the animal’s dietary history, the anticipated owner compliance, the cost of the diet, and palatability for the species concerned.

Chapter 9 — Duration of the Diet, Monitoring, and Response Criteria

9.1 — Evidence-Based Recommendations

The meta-analysis by Olivry, Mueller, and Prélaud (2015) constitutes the reference for determining the optimal duration of the elimination diet. This analysis compiled data from multiple studies in which the kinetics of clinical response to the diet had been documented. Results show that a duration of 5 weeks allows achieving remission in 80% of canine responders and 85% of feline responders. A duration of 8 weeks brings this rate to 90% in both species. Therefore, the minimum recommended duration is 8 weeks, with extension to 10-12 weeks in complex cases (concurrent EAD, recurrent superinfections, partial response at 8 weeks).

Analysis of response kinetics shows that 50% of canine responders present significant improvement by the third week of diet, and 80% by 5-6 weeks (Olivry 2015). In cats, kinetics are comparable with 85% remission at 6 weeks. The study by Lewis et al. (2025) confirms that more than half of subjects diagnosed with CAFR require more than 4 weeks to show a significant reduction in PVAS score, with a baseline PVAS score of 7.4 reduced by 1.8 ± 2.2 points after 8 weeks.

The 8-week duration brings the remission rate to 90% in both species, a threshold beyond which marginal diagnostic gain becomes minimal (Olivry 2015). This 90% threshold constitutes the scientific rationale for the international recommendation of 8 weeks as the minimum standard duration of the elimination diet.

9.2 — Recommended Duration: Minimum 8 Weeks and 10 to 12 Weeks in Complex Cases

The remaining 10% of responders require an extension to 10-12 weeks, justified in cases presenting concurrent EAD not yet stabilized, persistent superinfections, or complex allergen history. Fischer et al. evaluated a shortened elimination diet protocol and showed that diagnostic sensitivity decreased significantly below 6 weeks, confirming that any shortening of the protocol exposes to a risk of false negatives (Fischer 2021).

9.3 — Clinical Monitoring

Clinical monitoring during the elimination diet relies on regular appointments: week 2 (compliance verification and treatment of superinfections), week 4 (first interim evaluation), week 8 (final response evaluation). Parameters to evaluate include the pruritus score (PVAS), the cutaneous lesion score (CADESI-04 in dogs, SCORFAD in cats), the condition of the coat and skin, frequency and consistency of stools, and the animal’s general well-being.

9.4 — Objective Evaluation Tools: PVAS, CADESI, SCORFAD

SCORFAD (Scoring Feline Allergic Dermatitis) is a validated score specific to cats, evaluating excoriative lesions, miliary dermatitis, self-induced alopecia, and eosinophilic complex lesions. CADESI-04 (0-180) and PVAS (0-10) complete the battery of standardized tools in dogs. Combined use of these scores enables objective, reproducible, and comparative monitoring between appointments.

9.5 — Management of Secondary Superinfections During the Diet: Do Not Confuse Them with Failure

Management of secondary superinfections (Staphylococcus pseudintermedius pyoderma, Malassezia pachydermatis dermatitis, otitis) during the diet is imperative: their persistence may simulate diet failure and must not be confused with absence of response to dietary exclusion. Targeted antimicrobial treatment for pyoderma and/or antifungal treatment for Malassezia dermatitis must be initiated in parallel with the diet based on analyses.

Chapter 10 — The Provocation Challenge: Why Is It Indispensable?

10.1 — Definition and Justification

The provocation challenge (oral food challenge, OFC) consists of reintroducing the former food or a specific ingredient after the elimination period, in order to confirm the CAFR diagnosis through recurrence of clinical signs. Remission under an elimination diet without provocation constitutes only a presumptive diagnosis: clinical improvement may result from non-specific effects of the dietary change (modification of gut microbiome, better digestibility, reduction of biogenic amines). The challenge is the only means to distinguish a true CAFR from a fortuitous improvement and to confirm the diagnosis.

10.2 — Time to Recurrence of Signs: 7–14 Days According to Studies

The time to recurrence of clinical signs after challenge (Time to Flare, TTF) constitutes a key parameter for interpreting provocation challenges. In dogs, 85% of positive challenges manifest within the first 7 days, and 95% within the first 14 days. In cats, the delay is comparable, with 80% of recurrences within 7 days and 90% within 14 days. Shimakura and Kawano reported a median TTF of 3 days (range: 1-14 days) in Japanese dogs subjected to individual food challenges (Shimakura 2021).

10.3 — 2020 Data: Meta-Analysis on Post-Challenge Flare Delay (234 Dogs, 83 Cats)

The meta-analysis by Olivry and Mueller (2020), covering provocation challenges in 234 dogs and 83 cats, confirms these delays and provides the most solid database to date. Cutaneous reactions (erythema, pruritus) appear on average more rapidly (median: 2-3 days) than digestive signs (median: 5-7 days). This data justifies a minimum provocation duration of 14 days before concluding a negative result.

10.4 — Owner and Practitioner Reluctance: Communication Strategies

Owner reluctance to perform the provocation challenge constitutes a frequent obstacle in clinical practice. After 8 weeks of a demanding and costly diet, the prospect of a voluntary recurrence of itching in their companion is often poorly accepted. The communication strategy must emphasize that the provocation is essential to confirm the diagnosis, adapt long-term management, and identify specific allergens to avoid. The veterinary dermatologist’s opinion helps overcome this reluctance by explaining that the provocation is of short duration and that signs are reversible.

10.5 — Individual Ingredient Challenges: Sequential Methodology

The individual provocation protocol consists of reintroducing a single ingredient (for example: plain cooked chicken) for 7 to 14 days, while maintaining the elimination diet as the base. In cases of sign recurrence, the ingredient is removed and the elimination diet is resumed until remission before testing the next ingredient. This sequential approach allows identifying individual allergens and building a personalized maintenance diet.

10.6 — Value of the Challenge in Distinguishing CAFR from Concurrent EAD

The provocation challenge with complete return to the former food allows distinguishing CAFR from concurrent EAD. If pruritus does not recur despite complete reintroduction, the dietary component is excluded and the diagnosis must be reassessed in favor of strictly environmental EAD. If pruritus only partially recurs, coexistence of CAFR and EAD is likely — a scenario estimated in 13 to 33% of atopic dogs (Jackson 2023).

10.7 — Practical Provocation Protocol: Duration per Ingredient, Management of Positive Results

Each ingredient must be reintroduced for 7 to 14 days. Positivity is defined by the reappearance of pruritus (increase in PVAS ≥2 points) or recurrence of cutaneous lesions (increase in CADESI-04 ≥15 points). In cases of positive provocation, the ingredient is immediately removed and the elimination diet is resumed for 2 to 4 weeks before testing the next ingredient. The order of provocations prioritizes the most frequently implicated proteins (beef, chicken, dairy products) first.

10.8 — Summary Box: “Why Is the Provocation Test Mandatory to Confirm the Diagnosis?”

The provocation test remains mandatory because remission under an elimination diet alone constitutes only a presumptive diagnosis. Clinical improvement may result from non-specific factors: modification of gut microbiome, reduction of biogenic amine intake, improved digestion, or even seasonal fluctuations of EAD. Only the reproducible recurrence of signs upon reintroduction of the former food confirms the causal link between allergen ingestion and clinical manifestations.

PART VI — HOME-PREPARED DIET VERSUS COMMERCIAL DIET

Chapter 11 — Home-Prepared Diet: Benefits, Protocol, and Risks

11.1 — Advantage #1: Absolute Certainty of Composition, Absence of Cross-Contamination

The main advantage of the home-prepared diet lies in the absolute certainty of its composition: the owner controls each ingredient, eliminating any risk of cross-contamination. Unlike commercial foods, no shared manufacturing line can introduce undeclared allergens. This certainty is particularly valuable in polyallergic animals or those who have failed a hydrolyzed commercial diet.

The protocol relies on the principle of a single protein/carbohydrate pair: a single protein source associated with a single carbohydrate source, with no other added ingredient (no salt, no flavored oil, no spices, no sauce). This principle of maximum simplicity maximizes diagnostic reliability by limiting dietary variables to two identifiable components.

Selection of the protein source must be guided by the animal’s exhaustive dietary history. Recommended sources in 2026 include rabbit, venison, kangaroo, duck, trout, tilapia, and goat. Choosing a protein never previously ingested by the animal is the absolute prerequisite of the approach.

Authorized carbohydrate sources include white rice, potato, quinoa, and sweet potato. White rice constitutes the safest carbohydrate source from a nutritional standpoint and is the best tolerated by the canine and feline digestive system. Quinoa, while potentially usable, contains antinutrients and its digestibility is lower; it is less recommended as a first choice. Potato remains a valid option for an elimination diet of limited duration (8-12 weeks). Cooking is mandatory: thermal denaturation modifies the three-dimensional structure of proteins and may reduce their IgE reactivity, although certain heat-resistant sequential epitopes maintain their allergenicity. The recommended protein/carbohydrate ratio is 1:2 to 1:3 by fresh weight.

11.2 — Mandatory Cooking: Effect of Thermal Denaturation on IgE-Reactive Epitopes

Cooking at a temperature above 70°C for at least 20 minutes causes denaturation of dietary proteins, altering the conformational epitopes recognized by IgE. However, linear (sequential) epitopes resist this denaturation and maintain residual allergenic potential. Beef and chicken thus retain significant allergenicity after cooking, as evidenced by the positive provocation rates reported in the literature.

Prolonged boiling (>30 minutes at 100°C) further reduces allergenicity compared to rapid high-temperature cooking (grilling or pan-frying), by fragmenting conformational epitopes without generating neo-antigens.

Conversely, dry cooking at high temperature (>120°C — oven, grill, frying, extrusion) triggers the Maillard reaction, a non-enzymatic glycation of proteins that creates new antigenic structures (advanced glycation end products, AGEs) potentially increasing the immunogenicity of cooked foods (Koppelman 2021). Van Broekhoven et al. confirmed that intensive thermal processes modify the cross-reactive allergenic profile of arthropod proteins, with direct implications for insect-based diets (Van Broekhoven 2016). Therefore, boiling constitutes the recommended cooking method for home-prepared elimination diets, preferable to any dry cooking to minimize the residual allergenicity of the proteins used.

11.3 — Absolute Prohibitions: Salt, Flavored Oils, Spices, Sauces, Additives

The prohibitions of the home-prepared elimination diet are absolute: no salt, no flavored oil, no spices, sauces, condiments, or additives may be added to the preparation. Any deviation, however minor, may introduce hidden proteins (beef broth, chicken flavoring) capable of distorting the diagnostic result. Neutral vegetable oils (canola, sunflower) are authorized in limited quantities as a source of essential fatty acids.

11.4 — Nutritional Risks

The nutritional risks of the home-prepared diet constitute its main limitation. A diet composed exclusively of one meat and one starch is systematically unbalanced in calcium (inverted Ca/P ratio of 1:10-1:20 instead of 1:1-2:1), in essential fatty acids (omega-3 and omega-6), in fat-soluble vitamins (A, D, E), and in trace elements (zinc, copper, iodine). Stockman et al. evaluated home-prepared diet recipes: 95% did not meet minimum AAFCO or FEDIAF nutritional standards (Stockman 2013).

11.5 — Necessity of Supervision by a Veterinary Nutritionist Beyond 4–6 Weeks

Beyond 4 to 6 weeks, supervision by a veterinary nutritionist is recommended to formulate a balanced maintenance diet if the home-prepared diet must be continued long-term. This specialized consultation enables calculation of macro- and micronutrient intakes, adjustment of quantities, and prevention of long-term deficiencies that could compromise the animal’s health and vitality.

11.6 — Systematic Supplementation

Systematic supplementation with calcium carbonate (100-200 mg/kg of fresh food), fish oil rich in omega-3 (EPA/DHA, 50-100 mg/kg/day), vitamin complex, and zinc is essential from the start of the diet. The benefits of this supplementation go beyond simple deficiency correction: omega-3 fatty acids exert a documented anti-inflammatory effect on the skin barrier (reduction of PGE2 and LTB4 production) that may contribute to the clinical improvement observed during the diet.

11.7 — Inadequacy for Permanent Use Without Balanced Formulation

A home-prepared diet not formulated by a veterinary nutritionist is unsuitable for permanent use. Cumulative deficiencies in calcium, zinc, and fat-soluble vitamins lead to bone problems (osteodystrophy in puppies, pathological fractures in adults), cutaneous problems (alopecia, hyperkeratosis), and immunological issues after several months. Therefore, transitioning to a balanced therapeutic commercial food or having a complete home-prepared diet formulated by a specialist constitutes an imperative beyond the diagnostic phase.

Chapter 12 — Commercial Diet: Advantages, Disadvantages, and Cross-Contaminations

12.1 — Advantages of Industrial Veterinary Diets: Convenience, Tested Palatability, Nutritional Balance

Therapeutic veterinary commercial diets offer major practical advantages: ease of implementation, tested palatability, complete nutritional balance compliant with AAFCO/FEDIAF standards, and in-plant quality control. Their formulation guarantees adequate intake of nutrients, fats, vitamins, and trace elements, eliminating the nutritional deficiency risk inherent in unformulated home-prepared diets.

12.2 – Caution with OTC Hypoallergenic Diets

Cross-Contamination: A Major Problem with OTC Foods

Cross-contamination of OTC (over-the-counter, non-veterinary) commercial foods constitutes, however, a major problem, documented by multiple independent studies using molecular detection techniques (PCR, ELISA, microarray). This phenomenon results from shared production lines, contamination of raw materials, and the absence of validated cleaning procedures between manufacturing runs.

Systematic Review: 40% of OTC Batches Contaminated

Olivry et al. demonstrated that 40% of OTC food batches contained undeclared allergens not listed on the label (Olivry 2018). Ricci et al. (2018) analyzed 11 wet limited-antigen dietary foods by PCR microarray: 54.5% (6/11) were contaminated by undeclared animal proteins. Horvath-Ungerboeck et al. had reported similar results for dry foods, with beef and pork as the most frequent contaminants (Horvath-Ungerboeck 2017).

PCR/ELISA Data: 100% of Tested Feline Foods Containing Undeclared DNA

Kępińska-Pacelik et al. (2023) confirmed by quantitative PCR that 65% of OTC canine kibble contained undeclared chicken DNA, and 41% undeclared pork. Preckel et al. (2023) detected by 16S rDNA metagenomic analysis up to 19 undeclared animal species in a single sample. For feline foods, Preckel et al. and Kępińska-Pacelik et al. (2023) showed that 100% of tested samples contained DNA from undeclared species (Preckel 2023). These data raise major traceability issues for the pet food industry and call into question the reliability of limited-antigen kibble and wet foods sold in retail stores.

2022–2024 Data: 27% of Canine Kibble Containing Undeclared Chicken DNA

The extent of contamination documented between 2022 and 2024 confirms that this phenomenon is not anecdotal. The converging data from Kępińska-Pacelik (2023) and Preckel (2023) demonstrate that OTC “limited antigen” foods cannot be considered reliable for an EDT. The sensitivity of current PCR methods (detection of DNA at concentrations on the order of picograms) reveals contaminations invisible to standard analyses, making visual or chemical verification insufficient.

Contamination Mechanisms: Shared Lines, Contaminated Raw Materials

Contamination mechanisms are multiple: shared production lines between different formulas (manufacturing chicken kibble on the same line as a “chicken-free” diet leaves protein residues), upstream contamination of raw materials (animal meals, fats, flavorings), and cross-contamination during storage and packaging. The absence of regulations mandating systematic PCR control of OTC batches worsens this situation.

Regulatory Conclusion: OTC Foods Must Not Be Used for an EDT

OTC foods, including those labeled “hypoallergenic” or “limited antigen,” must not be used for a diagnostic elimination diet. Only therapeutic veterinary foods manufactured on dedicated lines and subject to quality control by PCR/ELISA offer sufficient reliability to guarantee the absence of cross-contamination (Olivry 2017).

12.3 — Dedicated Veterinary Foods: Quality Control by PCR on Each Batch

Dedicated therapeutic veterinary foods for EDT are distinguished by specific manufacturing protocols: dedicated production lines or lines cleaned according to validated procedures, quality control by PCR and/or ELISA on each batch before delivery, complete traceability of raw materials. The main brands integrate these controls into their manufacturing process, achieving compliance in internal quality audits.

12.4 — Comparative Table: Home-Prepared vs. Therapeutic Commercial vs. OTC

The choice between a home-prepared diet and a therapeutic commercial diet depends on the clinical situation, owner compliance, and logistical constraints. The home-prepared diet offers absolute certainty of composition but requires strict compliance and nutritional supplementation. The therapeutic commercial diet offers complete nutritional balance and ease of use but carries a residual risk of cross-contamination. OTC foods, with a contamination rate of 27 to 54%, are contraindicated for any diagnostic EDT.

PART VII — DIFFERENT TYPES OF HYPOALLERGENIC COMMERCIAL DIETS

Chapter 13 — Novel Protein Diets

13.1 — Fundamental Principle: Individual Immunological Novelty

The principle of novel protein diets rests on immunological novelty: the animal cannot develop an allergic reaction to a protein to which its immune system has never been exposed. This notion is individual and contextual: a protein considered “novel” for one animal may be a common allergen for another.

Lamb, long considered a hypoallergenic protein, no longer meets this criterion in 2026 due to its frequent presence in mass-market kibble and wet foods. Likewise, salmon and duck, once considered rare proteins, have become common ingredients in mass-market lines, reducing their utility as “novel” proteins.

Recommended protein sources in 2026 include venison, kangaroo, rabbit, quail, capelin, pollock, trout, and goat. These proteins remain relatively rare in mass-market commercial formulas and offer a high probability of immunological novelty for most animals.

13.2 — Cross-Reactivities to Anticipate When Selecting

Cross-reactivities between taxonomically close species must be anticipated when selecting: a dog sensitized to beef presents a risk of cross-reactivity with lamb and venison (Ruminantia), and a dog sensitized to chicken will likely react to duck and turkey (Galliformes/Anseriformes), with an IgE cross-reactivity rate of 97% between chicken and duck (Olivry 2017). This cross-reactivity is documented for specific proteins and reflects molecular homologies between taxonomically close species, without necessarily extending to all proteins of these species.

13.3 — Limitations: Growing Difficulty in Finding a Naive Source

The growing difficulty of finding a “naive” protein source — due to the diversification of commercial food formulas and the presence of undeclared animal by-products — constitutes a major limitation of this approach. A recent article by Villaverde (2024) emphasizes that detailed analysis of the animal’s dietary history has become more complex as brands multiply recipes based on exotic proteins. Insect proteins (Hermetia illucens, Tenebrio molitor), often presented as hypoallergenic novel proteins, cannot be considered as such in atopic animals sensitized to mites, due to documented IgE cross-reactivity via tropomyosin (Majewski 2021). However, the clinical demonstration that ingestion of insects triggers a dietary cutaneous exacerbation in dogs or cats sensitized to mites remains to be established by controlled provocation studies. At present, the use of insects as a protein source in an EDT therefore requires certain caution, and prior evaluation of the animal’s allergic status toward mites.

Chapter 14 — Technology and Value of Hydrolyzed Protein Diets

14.1 — Biochemical Principle of Enzymatic Hydrolysis

Enzymatic hydrolysis of dietary proteins consists of controlled cleavage of peptide bonds by proteases (trypsin, chymotrypsin, papain), reducing the molecular weight of the resulting peptides. The degree of hydrolysis, defined as the percentage of peptide bonds cleaved, determines the molecular weight distribution of the produced peptides and, consequently, the residual allergenic potential of the formulation.

The critical molecular weight threshold below which a peptide can no longer simultaneously cross-link two adjacent membrane-bound IgE molecules is approximately 5 kDa (Cave 2006). Below this threshold, the peptide cannot bridge IgE fixed on mast cell FcεRI receptors, preventing degranulation and release of inflammatory mediators.

IgE cross-linking requires that an allergen possess at least two epitopes 5 to 10 nm apart, capable of simultaneously binding to two adjacent IgE molecules on the mast cell membrane. A peptide of less than 5 kDa (approximately 40-45 amino acids) can only contain one functional epitope, making this cross-linking physically impossible. This physicochemical property constitutes the rational basis for hydrolyzed diets.

Standard hydrolysis produces peptides of less than 13 kDa, while extensive hydrolysis achieves molecular weights below 1-3 kDa. The study by Olivry et al. (2017) showed that extensively hydrolyzed poultry feathers (95% of peptides ≤1 kDa) induced no IgE recognition in the 40 dogs and 40 cats tested, whereas poorly hydrolyzed feathers generated a positive IgE response in 37% of dogs. The clinical difference is therefore directly correlated with the degree of hydrolysis.

Bizikova and Olivry clinically confirmed that the extensively hydrolyzed feather-based diet did not provoke a pruritic flare in allergic dogs (0/10 dogs), whereas the hydrolyzed chicken liver diet induced a recurrence in 40% of subjects (4/10, p = 0.04) (Bizikova 2016). Lewis et al. recently compared in a triple-blind randomized crossover multicenter trial a hydrolyzed salmon diet (78.2% of peptides ≤2 kDa) with a hydrolyzed feather diet, with no significant difference in efficacy between the two formulations (p = 0.516 for PVAS, p = 0.325 for CADESI-04) (Lewis TP 2025).

14.2 — Persistence of Residual Allergenicity: The Risk of Incomplete Hydrolysis

The persistence of residual allergenicity constitutes the main limitation of hydrolyzed diets. Incomplete hydrolysis (residual molecular weight >5-10 kDa) maintains peptides capable of cross-linking membrane IgE and triggering mast cell degranulation. This phenomenon explains failures reported with certain commercial hydrolyzed diets with insufficient degree of hydrolysis.

Masuda et al. (2020) demonstrated that 28.8% of canine sera showed detectable T lymphocyte stimulation in response to hydrolyzed diet extracts, confirming that hydrolysis, even extensive, does not completely suppress T-cell immunogenic potential. Peptides of 1-3 kDa still contain sufficient T epitope sequences to activate CD25low T lymphocytes, a pathway independent of IgE cross-linking.

14.3 — Disadvantages of Hydrolyzed Diets

Palatability represents an additional challenge: hydrolysis generates small size peptides with a bitter taste (due to the exposure of hydrophobic residues — leucine, valine, phenylalanine), which may reduce the animal’s acceptance of the diet. Palatability varies depending on the protein source (soy and poultry feathers generate different taste profiles) and the degree of hydrolysis (the more extensive the hydrolysis, the more pronounced the bitterness).

Hypoosmotic diarrhea, linked to the water influx into the intestinal lumen caused by the high osmotic load of small peptides and free amino acids, constitutes a transient adverse effect (1 to 2 weeks) managed by adding soluble fibers (beet pulp, psyllium) to the formulation. This phenomenon must not be confused with a sign of food intolerance to the diet itself.

14.4 — Major Advantage: Application Independent of Dietary History

The major advantage of hydrolyzed diets lies in their applicability independent of dietary history: regardless of the diversity of previously ingested proteins, extensive hydrolysis theoretically reduces the risk of reactivity. This property makes it the option of choice in animals with complex or unknown dietary history, and constitutes a valuable aid for the practitioner faced with an animal that has consumed multiple kibble lines.

14.5 — Prospective Randomized Crossover Multicenter Study

The study by Lewis et al. (2025), involving 57 pruritic dogs across 7 centers, constitutes the first triple-blind randomized crossover prospective multicenter study comparing two hydrolyzed formulations (salmon vs. poultry feathers). Results show equivalent diagnostic efficacy of both formulations, with a CAFR diagnosis rate of 44.7% (21/47 dogs completing the study). This study reinforces the validity of hydrolyzed diets as a first-line diagnostic tool in commercial EDTs.

Chapter 15 — Elemental Diets Based on Free Amino Acids

15.1 — Definition and Concept: Complete Absence of Intact Proteins or Peptides

Elemental diets based on free amino acids represent the most advanced form of dietary hypoallergenicity. These formulas contain no intact protein or residual peptide: the nitrogen source consists exclusively of synthetic amino acids, devoid of any epitope capable of being recognized by IgE or T lymphocytes.

Free amino acids, with molecular weight between 75 and 204 Da, are too small to constitute a conformational epitope (minimum 1-2 kDa) or sequential epitope (minimum 8-15 amino acids). Therefore, IgE-mediated and T-cell allergenic potential is theoretically zero, conferring on these diets the status of maximum hypoallergenicity standard.

Studies conducted in canine chronic enteropathies and data from Freiche et al. (2025) demonstrated the efficacy of these diets in dogs refractory to conventional hydrolyzed diets, with a clinical response rate of 76% on the CCECAI score. These results support the use of elemental diets as a last-line therapeutic option in complex cases.

15.2 — Indications: Failures of Conventional Hydrolyzed Diets

The main indications remain repeated failures of hydrolyzed and novel protein diets, severely polyallergic patients, and cases where dietary history is completely unknown. These situations, representing approximately 10 to 15% of EDTs in specialized practice, justify resorting to an elemental diet despite its constraints.

15.3 — Limitations: High Cost and Palatability

Limitations include high cost (2 to 3 times the price of a standard hydrolyzed diet), sometimes insufficient palatability (requiring a progressive transition and strategies encouraging food intake), and use reserved for refractory cases due to these constraints. Reduced palatability is explained by the taste profile of free amino acids, different from that of peptides or intact proteins.

PART VIII — ROLE OF NESTLÉ PURINA DIETS IN COMMERCIAL ELIMINATION

Chapter 16 — Purina Pro Plan HA Hypoallergenic Diets in Commercial EDTs

16.1 — Positioning of Purina Pro Plan HA in the Commercial EDT Offering

Purina Pro Plan Veterinary Diets HA (Hypoallergenic) is positioned in the commercial EDT offering as a hydrolyzed protein diet from a single source. The Purina HA line is distributed exclusively through veterinary channels, ensuring medical oversight of the diagnostic protocol.

The canine formulation relies on a soy hydrolysate as the sole protein source, combined with purified corn starch as the carbohydrate source. Soy constitutes a distinctive choice insofar as this legume is rarely implicated as a major allergen in dogs and cats, although soy sensitizations are documented in approximately 6% of confirmed cases in dogs.

The stated degree of hydrolysis achieves a molecular weight below 11 kDa for the majority of peptides. This threshold is above the 5 kDa threshold (Cave 2006) but below 13 kDa, placing Purina HA in the category of standard to moderate hydrolysis, distinct from the extensive hydrolysis (<1-3 kDa) offered by Royal Canin Anallergenic.

16.2 — Purina Pro Plan Feline HA (HA St/Ox): Formulation Specificities

The feline formulation (HA St/Ox) integrates additional urinary health management features (control of struvite and oxalate saturation), adapted to the specific needs of cats. Taurine and arachidonic acid intake is adjusted to meet the requirements of the obligate carnivore, and the quality of the hydrolyzed protein source is adapted to feline palatability.

16.3 — Advantages of Purina HA Diets in Clinical Practice

The advantages of Purina HA diets in clinical practice include the presence of a single protein source (hydrolyzed soy), a purified carbohydrate (corn starch), and high digestibility favorable to the animal’s digestive system comfort. High digestibility (>90%) contributes to a reduction in colonic fermentation and improves stool consistency, a parameter appreciated by owners on a daily basis.

Quality control relies on manufacturing protocols including cleaning of production lines between manufacturing runs and traceability of raw materials. Purina protocols include regular analyses on finished batches, limiting the risk of cross-contamination by undeclared proteins.

PART IX — FELINE SPECIFICITIES AND DIFFERENCES BETWEEN DOGS AND CATS

Chapter 17 — Differences in Performing an Elimination Diet in Dogs vs. Cats

17.1 — The Cat Is a Strict Obligate Carnivore

The cat is a strict carnivore whose nutritional needs differ from those of dogs. Protein needs are 1.5 to 2 times higher (minimum 26 g/100 g dry matter vs. 18 g in dogs), and certain essential nutrients cannot be synthesized by feline metabolism: taurine (essential for cardiac and retinal function), arachidonic acid (omega-6 fatty acid derived from animal sources), niacin, and preformed vitamin A.

A vegetarian diet is strongly discouraged in cats due to these predictable deficiencies. The absence of taurine leads within 4 to 12 weeks to dilated cardiomyopathy and irreversible retinal degeneration. The absence of preformed arachidonic acid compromises prostaglandin synthesis and platelet function. These metabolic constraints require that any feline elimination diet contain an animal protein source.

Dietary neophobia is a frequent behavior in cats, documented in the feline nutrition literature, which constitutes a significant obstacle to implementing elimination diets. Its exact prevalence in the context of EDTs has not been specifically quantified. A progressive transition over 7 to 10 days and adaptation of texture are recommended to promote acceptance of the new diet, by mixing increasing proportions of the new diet with the old food (days 1-2: 25/75; days 3-4: 50/50; days 5-7: 75/25; days 8-10: 100%). Acceptance is improved by gently warming the food and choosing a texture adapted to individual preferences.

17.2 — Major Risk Specific to Cats

The major risk specific to cats is hepatic lipidosis, a potentially fatal acute hepatic steatosis that occurs after prolonged fasting or food refusal beyond 48 to 72 hours, particularly in obese cats. Monitoring food intake constitutes a critical parameter in cats: any food refusal exceeding 48 hours requires stopping the diet and returning to the former food while awaiting an alternative strategy.

17.3 — Alternative Strategies in Case of Refusal: Change of Presentation (Kibble vs. Wet Food)

In cases of food refusal, several strategies can be considered: change of presentation (switching from kibble to wet food or vice versa), gentle warming of the food to release aromas. The variety of presentations available in therapeutic lines facilitates adaptation to individual cat preferences.

17.4 — Similar Response Kinetics in Dogs and Cats but Feline Particularities

The kinetics of response to the elimination diet are comparable between dogs and cats (6 to 12 weeks), with a minimum recommended duration of 8 weeks in both species. Feline particularities include a higher proportion of digestive signs (40-50% vs. 20-30% in dogs), a hepatic lipidosis risk absent in dogs, more frequent dietary neophobia, and the absolute necessity of covering taurine and arachidonic acid needs.

PART X — CAUSES OF FAILURE, LONG-TERM MANAGEMENT, AND PERSPECTIVES

Chapter 18 — Causes of EDT Failure and Complicating Factors

18.1 — Cause #1: Owner Non-Compliance (Flavored Medications, Treats, Outdoor Access)

Owner non-compliance represents the most frequent cause of EDT failure and must be systematically reassessed in cases of apparent failure. Sources of protocol deviation include unidentified flavored medications (palatable tablets containing chicken or beef proteins as excipients), treats given by third parties, and access to another animal’s food.

18.2 — Cause #2: Cross-Contamination of the Commercial Food Used

Cross-contamination of the commercial food used constitutes the second cause of failure. Recent PCR data show that most OTC foods contain undeclared proteins (Ricci 2018, Kępińska-Pacelik 2023). Switching to a therapeutic veterinary food manufactured on a dedicated line may resolve this type of failure.

18.3 — Cause #3: Concurrent Uncontrolled EAD Simulating Failure

Concurrent uncontrolled EAD can simulate diet failure by maintaining pruritus independently of the dietary component. Adding a treatment targeting the environmental component (oclacitinib, lokivetmab) allows discriminating between the two components and revealing partial improvement attributable to dietary exclusion.

18.4 — Cause #4: Residual Allergenicity of Hydrolysates

Residual allergenicity of hydrolysates, estimated in 25-40% of dogs according to Masuda (2020) data, explains the failures observed with certain hydrolyzed diets with insufficient degree of hydrolysis. Switching from a standard hydrolyzed diet (<13 kDa) to an extensively hydrolyzed diet (<1-3 kDa), home-prepared, or elemental may resolve this type of failure.

18.5 — Cause #5: Insufficient Duration (<8 Weeks)

Insufficient duration (<8 weeks) is an avoidable cause of failure. Recall that 10% of responders only show improvement between weeks 8 and 12 (Olivry 2015). An EDT interrupted prematurely may incorrectly lead to the exclusionary diagnosis of CAFR.

18.6 — Algorithm for Resolving Apparently Failed EDTs

The algorithm for resolving an apparently failed EDT comprises five sequential steps: verification of compliance (detailed history of everything the animal has ingested), treatment of residual secondary superinfections, change of diet (switching from a hydrolyzed diet to a novel protein diet or vice versa, switching to an elemental diet), addition of antipruritic treatment targeting the environmental component, and extension of duration to 12 weeks.

Chapter 19 — Long-Term Feeding After Diagnostic Confirmation

19.1 — Permanent Avoidance of Identified Allergens

Permanent avoidance of allergens identified through individual provocation challenges constitutes the nutritional imperative of long-term management. This avoidance must be absolute and permanent: reintroduction, even occasional, of an identified allergen provokes clinical recurrence within 2 to 14 days in the majority of cases (Olivry 2020).

19.2 — Strategy Without Individual Challenges with Maintenance of the Remission Diet

When individual challenges have not been performed (due to owner refusal or clinical choice), maintenance of the remission diet constitutes the default strategy. The animal continues the same elimination diet that led to clinical improvement, without any reintroduction attempt.

Periodic monitoring every 6 to 12 months is recommended, including a biological workup (protein profile, lipid profile), evaluation of coat and skin quality, and monitoring of weight and general vitality. This monitoring aims to detect early any nutritional deficiency, any new sensitization, or any clinical recurrence.

The risk of neo-sensitization to the maintenance diet protein is biologically plausible and reported anecdotally in specialized clinical practice, but its exact prevalence has not been quantified by published longitudinal studies. Periodic clinical monitoring (every 6 to 12 months) is recommended to detect any recurrence of signs that may reflect new sensitization.

19.3 — Protein Source Rotation: Empirical Strategy, Non-Robust Data

Protein source rotation, although proposed empirically, rests on no robust clinical data and cannot be recommended as a prevention strategy validated by evidence. Preventing sensitization by varying exposures is contradicted by the absence of controlled prospective studies. Maintaining a single diet that has demonstrated its efficacy remains the safest strategy in the current state of knowledge.

PART XI — Conclusion

The management of cutaneous adverse food reactions in dogs and cats rests on a rigorous diagnostic approach of which the elimination diet constitutes the cornerstone.

Advances of recent years — molecular characterization of allergens, development of extensively hydrolyzed diets (<1-3 kDa), prospective multicenter randomized studies comparing hydrolyzed formulations (Lewis TP 2025) — have reinforced the scientific basis of this approach without altering its fundamental principle: only strict dietary exclusion followed by the provocation challenge allows a definitive diagnosis. Cross-contamination of commercial foods, documented by recent PCR analyses (Ricci 2018, Kępińska-Pacelik 2023), requires constant vigilance in choosing the elimination food and favors therapeutic veterinary diets manufactured on dedicated lines. Data from Masuda et al. (2020) on residual T-lymphocyte stimulation by hydrolysates (28.8% positive responses) raise the question of optimizing hydrolysis processes to neutralize both IgE reactivity and T-cell reactivity.

References

Adin D, De Francesco TC, Keene B, Tou S, Meurs K, Atkins C, Aona B, Kurtz K, Barron L, Sharpe A. Dietary taurine depletion and dilated cardiomyopathy: views from the clinic. J Vet Intern Med. 2019;33:1343-1356.

Bexley J, Kingswell N, Olivry T. Serum IgE cross-reactivity between fish and chicken meats in dogs. Vet Dermatol. 2019;30:25-e5.

Bizikova P, Olivry T. A randomized, double-blinded crossover trial testing the benefit of two hydrolysed poultry-based commercial diets for dogs with spontaneous pruritic chicken allergy. Vet Dermatol. 2016;27:289-e70.

Cave NJ. Hydrolyzed protein diets for dogs and cats. Vet Clin North Am Small Anim Pract. 2006;36:1251-1268.

Coyner K, Schick A. Hair and saliva test fails to identify allergies in dogs. J Small Anim Pract. 2019;60:121-125.

Favrot C, Bizikova P, Fischer N, Rostaher A, Olivry T. The usefulness of short-course prednisolone during the initial phase of an elimination diet trial in dogs with food-induced atopic dermatitis. Vet Dermatol. 2019;30:498-e149.

Fischer N, Spielhofer L, Martini F, Rostaher A, Favrot C. Sensitivity and specificity of a shortened elimination diet protocol for the diagnosis of food-induced atopic dermatitis (FIAD). Vet Dermatol. 2021;32:247-e65.

Freeman LM, Stern JA, Fries R, Adin DB, Rush JE. Diet-associated dilated cardiomyopathy in dogs: what do we know? J Am Vet Med Assoc. 2018;253:1390-1394.

Freiche V, Dossin O, Leclerc A. An extensively hydrolysed protein-based extruded diet in the treatment of dogs with chronic enteropathy and at least one previous diet-trial failure: a pilot uncontrolled open-label study. BMC Vet Res. 2025;21:68.

Fujimura M, Masuda K, Hayashiya M. Flow cytometric analysis of lymphocyte proliferative responses to food allergens in dogs with food allergy. J Vet Med Sci. 2011;73:1309-1317.

Gaschen FP, Merchant SR. Adverse food reactions in dogs and cats. Vet Clin North Am Small Anim Pract. 2011;41:361-379.

Hensel P, Santoro D, Favrot C, Hill P, Griffin C. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet Res. 2015;11:196.

Hobi S, Linek M, Marignac G, Olivry T, Beco L, Nett C, Fontaine J, Roosje P, Bergvall K, Belova S, Koebrich S, Pin D, Debey B, Lian T, Bensignor E, Kano R, Zini E. Clinical characteristics and causes of pruritus in cats: a multicentre study on feline hypersensitivity-associated dermatoses. Vet Dermatol. 2011;22:406-413.

Horvath-Ungerboeck C, Widmann K, Handl S. Detection of DNA from undeclared animal species in commercial elimination diets for dogs using PCR. Vet Dermatol. 2017;28:373-e86.

Jackson HA. Food allergy in dogs and cats; current perspectives on etiology, diagnosis, and management. J Am Vet Med Assoc. 2023;261:S23-S29.

Kępińska-Pacelik J, Biel W, Natonek-Wiśniewska M, Krzyścin P. Assessment of adulteration in the composition of dog food based on DNA identification by real-time PCR. Anim Feed Sci Tech. 2023;298:115609.

Koppelman SJ, Srncova K, Gaspari M. Thermal processing impacts the allergenicity of food: more than just protein denaturation. Curr Opin Allergy Clin Immunol. 2021;21:259-266.

Lam AT, Johnson LN, Heinze CR. Assessment of the clinical accuracy of serum and saliva assays for identification of adverse food reaction in dogs without clinical signs of disease. J Am Vet Med Assoc. 2019;255:812-816.

Lewis TP II, Moore GE, Laporte C, Daristotle L, Frantz NZ. Evaluation of hydrolyzed salmon and hydrolyzed poultry feather diets in restrictive diet trials for diagnosis of food allergies in pruritic dogs. Front Vet Sci. 2025;12:1560806.

Majewski C, Marti E, Ehrengruber M, Schüpbach G, Keller SM, Vidondo B, Dolf G, Gerber V, Mock M, Roosje PJ. Insect protein-based diet as potential risk of allergy in dogs. Animals (Basel). 2021;11:1942.

Masuda K, Sato A, Tanegashima K, Tani H, Tarui T, Konishi S, Mori A, Murakami M, Arai N, Haginoya N, Miyoshi N. Hydrolyzed diets may stimulate food-reactive lymphocytes in dogs. J Vet Med Sci. 2020;82:177-183.

Mueller RS, Olivry T. Critically appraised topic on adverse food reactions of companion animals (4): can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests? BMC Vet Res. 2017;13:275.

Mueller RS, Olivry T. Critically appraised topic on adverse food reactions of companion animals (6): prevalence of noncutaneous manifestations of adverse food reactions in dogs and cats. BMC Vet Res. 2018;14:341.

Mueller RS, Unterer S. Adverse food reactions: pathogenesis, clinical signs, diagnosis and alternatives to elimination diets. Vet J. 2018;236:89-95.

Olivry T, Bexley J, Mougeot I. Extensive protein hydrolyzation is indispensable to prevent IgE-mediated poultry allergen recognition in dogs and cats. BMC Vet Res. 2017;13:251.

Olivry T, Mueller RS, Prélaud P. Critically appraised topic on adverse food reactions of companion animals (1): duration of elimination diets. BMC Vet Res. 2015;11:225.

Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (3): prevalence of cutaneous adverse food reactions in dogs and cats. BMC Vet Res. 2017;13:51.

Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (5): discrepancies between ingredients and labeling in commercial pet foods. BMC Vet Res. 2018;14:24.

Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (7): signalment and cutaneous manifestations of dogs and cats with adverse food reactions. BMC Vet Res. 2019;15:140.

Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (9): time to flare of cutaneous signs after a dietary challenge in dogs and cats with food allergies. BMC Vet Res. 2020;16:158.

Preckel L, Brünen-Nieweler C, Denay G, Horlamus S, Zeeb S. Identification of mammalian and poultry species in food and pet food samples using 16S rDNA metabarcoding. Food Control. 2023;149:109677.

Pucheu-Haston CM, Mougeot I. Serum IgE and IgG responses to dietary antigens in dogs with and without cutaneous adverse food reactions. Vet Dermatol. 2020;31:116-127.

Ricci R, Conficoni D, Morelli G, Losasso C, Alberghini L, Giaccone V, Barrucci F, Ballarin C, Contiero B, Andrighetto I. Undeclared animal species in dry and wet novel and hydrolyzed protein diets for dogs and cats detected by microarray analysis. BMC Vet Res. 2018;14:209.

Rodrigues SD, Mendoza B, Dias MJ. Association of diet with treatment response in dogs with chronic enteropathy: a retrospective multicenter study. J Vet Intern Med. 2025;39:e70071.

Rodríguez-Pérez R, Pérez-Santos M, Villota-Eraso C, González-de-Olano D, García F, Yagüe-Jiménez V. Toward consensus epitopes B and T of tropomyosin involved in cross-reactivity across diverse allergens: an in silico study. Biomedicines. 2024;12:884.

Shimakura H, Kawano K. Results of food challenge in dogs with cutaneous adverse food reactions. Vet Dermatol. 2021;32:293-e280.

Silva LD, Martins T, Porsani MYH, Teixeira FA. The impact of a hypoallergenic diet on the control of oral lesions in cats: a case report. Animals (Basel). 2024;14:2656.

Stockman J, Fascetti AJ, Kass PH, Larsen JA. Evaluation of recipes for home-prepared maintenance diets for dogs. J Am Vet Med Assoc. 2013;242:1500-1505.

Van Broekhoven S, Bastiaan-Net S, de Jongh HH, Wichers HJ. Influence of processing and in vitro digestion on the allergic cross-reactivity of three mealworm species. Food Chem. 2016;196:1075-1083.

Villaverde C. Dietary options for diagnosis of cutaneous adverse food reactions. Companion Anim. 2024;29:2-7.

Vovk LG, Friedeck AD, Grzeskowiak LE, Toresson L, Ström Holst B, Hansson-Hamlin H. Serum food-specific IgE and IgG concentrations in healthy dogs and dogs with cutaneous adverse food reactions. Vet Dermatol. 2024;35:321-329.

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