Chin acne feline : Update on Diagnosis and Treatments

Chin acne feline, a common skin condition in felines, presents a significant diagnostic and therapeutic challenge for clinicians. Although limited, studies have highlighted varied clinical and histopathological aspects, emphasizing the need for a personalized approach.

This synthesis explores the facets of this dermatosis, from its clinical presentation to its optimal treatment, including appropriate diagnostic tools. It integrates data from prospective and retrospective studies, allowing for a comparative analysis of results and an in-depth discussion of controversial points in the literature.

Clinical Presentation and Epidemiology of Feline Acne

Clinical Manifestations: Significant Variability

Feline acne is characterized by inflammation of the pilosebaceous follicles, mainly located on the chin and lower lip. However, the clinical expression is far from uniform. The prospective study by Jazic et al. (2006), conducted on 22 cats, observed a predominance of comedones (73%), alopecia (68%), crusts (55%), papules (45%), and erythema (41%). Less frequent lesions, such as swelling (18%), pustules (9%), nodules/fistulas (9%), and scars (4.5%), were also reported. The presence of pruritus, reported in 35% of cats, is often linked to a secondary bacterial infection. The variability of clinical manifestations suggests pathogenic complexity. An unexpected observation highlights this diversity: a cat presenting with feline acne concomitant with generalized atopic dermatitis. This coexistence underscores the possibility of interactions between different skin conditions and the need for a complete clinical examination. It is important to note that the description of lesions may vary depending on the stage of acne development. Initial lesions, characterized by comedones (blackheads), can evolve into folliculitis (inflammation of hair follicles) and, in the most severe cases, into furunculosis (formation of boils). The precise description of lesions, their size, color, consistency, and the presence or absence of suppuration, is crucial to guide diagnosis and treatment choice.

Photo 1: Extensive feline acne lesions with the presence of comedones

Epidemiology: Retrospective Study and Statistical Analysis

The retrospective study by Scott et al. (2010) on 74 cats revealed a prevalence of feline acne of 5.3% among feline dermatology cases and only 0.3% of all cats examined in a veterinary hospital over a 15-year period. This difference potentially highlights a sampling bias, with severe cases being more likely to receive specialized consultation. The study did not reveal a predilection for a specific age, breed, or sex, although Jazic et al. (2006) observed a predominance in neutered males (73%). This divergence highlights the need for larger, better-controlled studies to refine the understanding of the epidemiology of feline acne. The age of lesion onset is particularly variable, ranging from 6 months to 14 years with a median of 4 years according to Jazic et al. (2006), refuting the hypothesis of a direct correlation with the pubertal stage. Breed does not appear to be a significant risk factor, although a slight overrepresentation of short-haired domestic cats might be observed in some studies. This could be due to sampling bias or unidentified factors. More in-depth studies, including genetic analysis, would be useful to clarify this point. The influence of environmental factors and local hygiene warrants further investigation. These studies could include comparative analyses between indoor and outdoor cats, as well as an assessment of the impact of the type of food bowls.

Physiopathology and Etiological Factors: Multifactorial Approaches

Feline acne is classically described as an idiopathic disorder of follicular keratinization. However, several factors could interact in its complex pathogenesis, a hypothesis supported by the observation of high variability in manifestations. The high variability observed in the clinical and histopathological manifestations of this condition suggests a multifactorial etiology.

Role of Microorganisms: Secondary Bacterial Infection and Mycology

A secondary bacterial infection is frequently observed in feline acne, worsening inflammation and pruritus. Studies have shown that coagulase-positive staphylococci and alpha-hemolytic streptococci are the most commonly isolated. The study by Jazic et al. (2006) reported bacterial isolation in 45% of cases. Cytological examination is therefore crucial for diagnosis to highlight bacteria and inflammatory cells (neutrophils) and thus guide the therapeutic choice. Regarding mycology, the involvement of dermatophytes, such as Microsporum canis, seems rare. Only a small proportion of cats with feline acne also present an infection with Malassezia pachydermatis. The exact role of these fungi remains to be clarified. Further studies are needed to determine whether this is a co-infection or a secondary colonization without clinical significance.

Photo 2: Superinfections are frequent in feline acne

Virological Factors: The Enigma of FHV-1 and FCV Viruses

The role of viruses in the pathogenesis of feline acne remains controversial. The identification by immunohistochemistry of feline calicivirus (FCV) antigen in a study by Jazic et al. (2006), in a single subject from a family cluster, suggests a possible but unconfirmed involvement. This study specifies that the majority of feline acne cases were not associated with FHV-1 or FCV infection. The technique used (IHC) is less sensitive than PCR; it would be interesting to carry out studies using the latter to confirm this hypothesis. Furthermore, more in-depth studies including viral genome analysis, viral quantification, and a study of the immune status of carrier cats should allow us to determine more precisely whether there is a viral role in feline acne or not.

Other Potential Factors: Hygiene, Stress, and Genetic Predispositions

Several other factors are potentially involved in the development of feline acne, including hair growth disorders, poor hygiene habits, and stress. However, the influence of these factors remains controversial. Studies have shown that plastic bowls could promote the development of acne lesions, this hypothesis being linked to an accumulation of bacteria in the plastic. However, changing plastic bowls does not necessarily improve the disease; it is possible that some bacteria are already present at the follicular level, and therefore a simple improvement in external hygiene is not enough. A retrospective study by Scott et al. did not show a correlation between stress and the onset of feline acne. Further research is needed to assess the impact of stress. The involvement of genetic factors remains a perspective to explore. Large-scale genomic studies should be able to demonstrate a correlation between one or more genes and feline acne, which could make it possible to better identify cats predisposed to the disease. These genetic studies could also identify biomarkers, which would then allow for better diagnosis and management of the disease.

Diagnosis and Differential Diagnosis: Clinical Approach and Complementary Examinations

The diagnosis of feline acne is mainly based on clinical examination, based on the clinical characteristics of the lesions and their preferential location on the chin and/or lips.

Clinical Examination: Characteristic Lesions and Anamnesis

Clinical examination, coupled with precise anamnesis, is essential. Comedonic lesions, sometimes associated with folliculitis or furunculosis, are the main signs. The presence of pruritus, variable depending on the case, suggests a possible secondary bacterial infection. Assessment of the patient’s hygiene habits (type of bowls, cleaning frequency) is crucial for implementing an adequate therapeutic strategy. Indeed, in the case of uncomplicated feline acne, hygiene improvements often lead to an improvement in symptoms. The anamnesis should take into account the history of previous skin diseases, the occurrence of trauma to the chin, exposure to other animals, diet, stress, or any other recent change within the home. The clinical examination should also include an assessment of the cat’s general condition and the presence of other clinical signs suggestive of other diseases.

Cytological Examination: Detection of Bacterial Infection

Cytological examination of samples taken by smear or fine-needle aspiration allows the identification of inflammatory cells (neutrophils) and bacterial flora, thus confirming the secondary bacterial infection. Gram staining allows the identification of bacteria and guides towards appropriate antibiotic treatment. This technique makes it possible to differentiate simple follicular obstruction from secondary bacterial infection. The combination of a clinical examination and a cytological examination constitutes a powerful diagnostic tool for diagnosing feline acne.

Complementary Examinations: Exploration of Differential Diagnoses

Complementary investigations should be considered in complex or treatment-resistant cases. Conditions such as demodicosis, dermatophytosis, and Malassezia dermatitis, which share clinical similarities with feline acne, should be ruled out. The absence of Demodex or dermatophytes in most of the studies suggests a weak association between these conditions and feline acne. Skin biopsy provides more precise histopathological information, allowing characterization of inflammation, confirmation of acne diagnosis, and exposure of underlying causes, particularly in refractory cases. Histopathological examination allows visualization of follicular obstruction, perifollicular inflammation, and lymphocytic infiltration. In case of doubt about a possible tumor, a histopathological examination is essential. The presence of other skin lesions, information about the patient’s lifestyle (indoor, outdoor, proximity to other animals), can also provide useful information.

Therapeutic Approaches: Targeted Strategies and Personalized Follow-up

The management of feline acne varies depending on the severity of the lesions and the response to treatment. An individualized approach is essential to optimize treatment and avoid recurrences or side effects.

Hygiene Measures: An Essential Preventive Approach

Local hygiene is paramount in the management of feline acne. Replacing plastic bowls, which are often porous and promote bacterial growth, with stainless steel or ceramic bowls is recommended. Regular cleaning of the bowls, at least once a day, with hot water and antiseptic soap is also essential. It is important to regularly clean the cat’s chin with a soft cloth soaked in warm water, and a mild antiseptic shampoo can be used once a week.

Topical Treatments: Antiseptic and Comedolytic Agents

For mild forms, topical treatments may suffice. The use of antiseptic shampoos (chlorhexidine, povidone iodine) is recommended for cleaning and eliminating bacteria. Benzoyl peroxide, although potentially irritating, is a possibility for its comedolytic action, but its use must be carefully monitored and its application limited due to its irritating potential. In addition, it can stain hair and fabrics. Salicylic acid, in solution or shampoo, can also be used, with or without another treatment. Application should be daily or as directed.

Systemic Treatments: Antibiotics and Corticosteroids

Severe secondary bacterial infections require systemic treatment with appropriate antibiotics (amoxicillin-clavulanate, clindamycin, etc.), ideally guided by an antibiogram to ensure the best therapeutic efficacy and minimize the risk of bacterial resistance. A bacteriological examination is therefore indicated in cases of purulent lesions or bacterial superinfection. In cases of significant inflammation, short-term corticosteroid therapy may be considered to relieve pain and pruritus, but with increased vigilance regarding potential side effects (immunosuppression, diabetes, etc.). Corticosteroid therapy should be short-term and at a low dose to limit these effects. Other treatments can be used, such as antihistamines in case of pruritus.

Follow-up: Key Steps and Treatment Adaptation

Regular follow-up is imperative for assessing treatment efficacy and adapting the therapeutic strategy according to clinical evolution. Improvement of lesions, absence of side effects, and hygiene are crucial points. A follow-up visit is necessary 1 or 2 weeks after the start of treatment, then periodically depending on the patient’s evolution. In case of no improvement or persistent pruritus, it is essential to re-evaluate the situation and modify the treatment. It is also important to discuss anamnesis, hygiene, and treatments with the owner to maintain the continuity of patient care.

Discussion and Perspectives: Synthesis of Knowledge and Research Areas

The diagnostic and therapeutic approach to feline acne depends on its severity and evolution. Despite current knowledge, uncertainties remain regarding etiopathogenesis, making management sometimes complex.

Multifactorial Etiology: Holistic Approach

Multifactorial etiology is the most likely hypothesis, with a combination of several factors being at the origin of this condition. The interaction between genetic, environmental, and immune factors seems to play a major role in the development of the disease. It is important to consider the various contributing factors (hygiene, stress, diet, hormonal dysfunction, genetic predisposition) to better interpret the evolution of the disease and adapt management.

Limitations of Existing Studies and Sampling Bias

The lack of prospective, randomized, controlled studies with large sample sizes constitutes a significant limitation in the evaluation of therapeutic options and in the understanding of the physiopathology of feline acne. Retrospective studies, while useful, are subject to selection bias and may not be representative of the entire feline population. The small sample sizes in many studies limit statistical power and the generalization of results.

Research Perspectives: Exploration of New Axes

Many research avenues remain to be explored to improve the understanding of feline acne and develop innovative therapeutic approaches. The study of genetic factors, for example, could identify genes that predispose to the disease. The identification of biomarkers, allowing for earlier diagnosis of the disease, would also be very useful. Further investigation into the role of bacterial and/or viral infections, using molecular techniques, is essential to characterize the participation of these infectious agents in the pathogenesis of the disease. Finally, the development of new molecules and therapeutic methods, such as topical treatments based on new comedolytic agents, could improve the prognosis for some cats.

Conclusion and Recommendations

Feline acne is a relatively common dermatosis in cats, characterized by follicular inflammation on the chin. The etiology is complex and potentially multifactorial, involving factors such as follicular obstruction, secondary and potentially viral bacterial infections. Diagnosis is based on clinical and cytological examination, with histopathological examination only indicated in refractory or complex cases. Treatment is individualized and combines improved hygiene practices, topical and/or systemic treatments depending on the severity of the lesions. Careful follow-up is essential to optimize management and prevent recurrences, as well as the occurrence of complications. Further studies are still needed to improve the understanding of pathogenesis and develop innovative therapeutic approaches.

FAQs

Q1: Is feline acne contagious?

A1: Available data do not allow us to affirm direct interfeline transmission. However, the observation of the simultaneous or successive appearance of this condition in several habitats shared by cats suggests a potential for infection, the route of contamination remaining undetermined. Further studies are needed to determine the possible role of an infectious, environmental, or even behavior-related factor in cats.

Q2: Is there a curative treatment for feline acne?

A2: Currently, there is no curative treatment. However, appropriate management significantly controls the condition and improves the cat’s long-term comfort. The goal of treatment is to control lesions and their complications, not to completely cure the disease.

Q3: What are the signs of a bacterial superinfection in the context of feline acne?

A3: A bacterial superinfection usually manifests as increased inflammation, the presence of pustules, significant erythema, and pruritus. Cytological examination is essential to confirm the presence of neutrophils and identify the bacteria involved. The presence of pus or purulent fluid suggests a more severe infection. Systemic signs such as fever may be observed in the most severe cases.

Q4: Does changing food bowls systematically improve feline acne?

A4: Several studies suggest that changing plastic bowls to bowls made of non-porous materials (ceramic, stainless steel) can be beneficial by reducing the accumulation of bacteria. However, this change is not systematically effective and is not enough to cure feline acne. Improved hygiene, while important, is only one of several factors involved in the development of the disease. The effectiveness of changing bowls depends on the importance of the hygienic factor in the onset of acne in each individual.

Q5: What is the optimal approach in cases of feline acne refractory to treatment?

A5: In these situations, a skin biopsy is strongly recommended to confirm the diagnosis and rule out other conditions. A re-evaluation of the cat’s environmental and behavioral factors will be carried out, taking into account the patient’s history and the effectiveness of previous treatments. Complementary examinations, such as bacteriological cultures and antibiograms, are essential to adapt the treatment, and specialist veterinary dermatology advice may be sought. The use of topical treatments in combination with systemic treatments (targeted antibiotics, immune modulators) may be considered, or a modification of the hygiene protocol. In the most recalcitrant cases, the use of immunosuppressants (exceptionally) may be considered under strict medical supervision.

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