Howie” is a 3 yo MN Golden retriever with progressive, non-pruritic scaling. The owner reported a year history of progressively worsening scaling with concurrent darkening of the skin on the abdomen and thighs. Pruritus was minimal to absent. The owner had tried bathing with an over-the-counter oatmeal shampoo with minimal improvement in the scaling.
Rebecca Mount, DVM, DACVD
Dermatology for Animals, Albuquerque, NM
May 2024
History
They saw the primary veterinarian for the persistent scaling who initiated trial treatment with an isoxazoline for ectoparasites and antibiotics for possible pyoderma. Additionally, full bloodwork with total T4 were performed with all values within normal reference range. The owner reported no change in scaling with the above therapies.
At the initial presentation the owner was still intermittently bathing the pet and had transitioned to a non-prescription sensitive skin and stomach diet. The dog was not on any medications or supplements. The progressive scaling persisted, but no other skin or health changes had been noted.
Exam
Moderate to marked loosely adherent white to grey scale adhered to the hair on the medial and caudal thighs. Moderate hyperpigmentation with marked accumulation of dry, grey to black scaling was noted on the thinly haired areas of the ventral abdomen, inguinal folds and medial thighs. There is mild white scaling on the dorsum. There is minimal to absent generalized erythema. The hair coat was normal thickness, color, and texture with no evidence of hair barbering. The paw pads and nasal planum were unaffected. Otoscopic exam was within normal limits. The rest of the dermatologic and physical exam were unremarkable.
Diagnostics
Initial diagnostics included cytology of the areas of heavy scaling (ventral abdomen and caudal thighs). Cytology revealed 4-6 Malassezia in most oil immersion fields. No inflammatory cells or bacteria were noted.
Options for confirmatory diagnosis of ichthyosis including skin biopsies or genetic testing were discussed. Due to the high clinical suspicion for Golden retriever ichthyosis, the less invasive genetic testing was elected. Cheek swaps were collected by the owner and submitted to the Veterinary Genetics Laboratory at UC Davis to be tested for both variants of Golden retriever ichthyosis. Results were homozygous Ich1/Ich1.
Assessment
Golden retriever ichthyosis with secondary Malassezia dermatitis.
Treatment Plan
The patient was start on ketoconazole at 6.3mg/kg every 24 hours for 21 days for the Malassezia dermatitis.
Treatment for the primary Golden retriever ichthyosis focused on scale removal and improvement of the skin barrier. A commercial veterinary omega 3 supplement was recommended daily. A topical routine with weekly to bi-weekly bathing with an anti-seborrheic shampoo containing ophytrium 0.5% was recommended. Additionally, in between bathing, a topical mousse containing ophytrium 0.5% was recommended to be applied daily to areas marked scaling (ventral abdomen, medial and caudal thighs) for 7 days, then 2-3 times weekly for maintenance. Finally, light combing of the hair to help remove adhered scale was discussed.
Follow-up
The patient presented for a recheck 8 weeks after the initial diagnosis. On physical exam the scaling was overall improved with mild adherent grey scale persisting in the hair the caudal thighs. Repeated cytology of the persistent scaling showed keratinocytes with no microbes or inflammatory cells.
At the 6 month recheck the owner had decreased the frequency of topical therapy as the patient’s scaling was well managed with minimal waxing and waning scaling noted by owner. No reoccurrence of the Malassezia dermatitis was noted.
Discussion
Golden retriever ichthyosis is an autosomal recessive cornification disorder that results in abnormal turnover of keratinocytes results in prominent scaling. There are two variants of ichthyosis in Golden retrievers. Ichthyosis type 1 (ICH-1) is thought to be due to a gene mutation in Golden retrievers is associated with the patain-like phospholipase domain containing protein 1 gene (PNPLA-1)1. Ichthyosis type 2 (ICH-2) is believed to be more severe and is caused by a mutation in the abhydrolase domain containing 5 (ABHD5)2. Both forms of Golden retriever ichthyosis are considered non-epidermolytic ichthyosis.
Since Golden retriever ichthyosis is a hereditary disease, clinical signs are often noted in young dogs with onset of scaling most commonly seen between 3 weeks and 3 years of age1,3. However, in some cases scaling will not be noted until later in adulthood5. The most common clinical signs are white-grey, loosely adherent scaling most prominent on the trunk1,2. Additionally, hyperpigmentation of the skin on the thinly haired areas of the axillary region, inguinal region, and ventral abdomen is common1,2,3. Ichthyosis is not typically an inflammatory or pruritic dermatoses, but erythema and pruritus may be present if there is secondary infection with bacterial or yeast.
In autosomal recessive congenital ichthyosis, clinical signs typically include generalized scaling and variable erythema.
Diagnosis is often made based on breed and clinical appearance, but histopathology or genetic testing are recommended for definitive confirmation of ichthyosis. Histological changes consistent with Golden retriever ichthyosis include: prominent compact to laminated orthokeratotic hyperkeratosis with lack of desquamation and marked melanic pigmentation3,5 and minimal to absent dermal inflammation2. Genetic testing can be used to support a clinical diagnosis of Golden retriever ichthyosis or to identify unaffected carriers in the breeding populations1,2. The Veterinary Genetic Laboratory at UC Davis offers testing for both Ich1 and Ich2, while PennGen at the University of Pennsylvania offers testing for Ich2.
Although considered primarily a cosmetic condition, the increased scale can increase the risk of secondary bacterial of Malassezia infections which can increase pruritus and patient discomfort. Current therapies are primarily focused on topical therapies that promote removal of the scale and improvement of the epidermal barrier function. One of the mainstays of ichthyosis therapy is the use keratolytic/keratoplastic shampoos and topicals to remove the scale. Common keratolytic topicals including, salicylic acid, benzoyl peroxide, zinc gluconate, tars, and selenium sulfides4, can be over drying and worsen scale in these cases1,3,5. Therefore, use of emollients to help remove scale is generally preferred in ichthyosis cases5. Additionally, in long coated breeds, frequent combing can help with scale removal4. Treatment should also focus on restoration of the skin barrier function with moisturizing agents that include phytosphingosines or ceramides5. Additionally, oral omega 3 and 6 fatty acid supplementation may be beneficial in these cases. Furthermore, there have been case reports of severe cases of ichthyosis being successfully managed with the oral retinoid, isotretinoin1. Based on the cost and side effect potential of isotretinoin, retinoids are most commonly reserved for severe cases that are affecting the pet’s quality of life1,5. Finally since secondary infection is common with ichthyosis, in addition to managing the primary scaling it is important to monitor cytology throughout treatment. If recurrent infection is playing a role, addition of antimicrobial shampoo or topical is recommended to reduce reliance on systemic antimicrobials.
Overall, the prognosis for Golden retriever ichthyosis is good, but will require life-long management.
References
- Petak, A., Sostaric-Zuckermann, IC., Hohsteter, M., et al. Isotretinoin Treatment for Autosomal Recessive Ichthyosis in a Golden Retriever. Veterinary Sciences. 2022; 9,97.
- Kiener, S., Weiner, DJ., Hopke, K., et al. ABHD5 frameshift deletion in Golden retriever ichthyosis. G3. 2022; 12 (2): 1-6
- Gauguere, E., Bensignor, E., Kury, S., et al. Clinical, histopathological and genetic data of ichthyosis in the golden retriever: a prospective study. Journal of Small Animal Practice. 2009; 50: 227-235
- Scott, D.W., Miller Jr, W.H., & Griffin, C.E. (2013). Muller and Kirk’s Small Animal Dermatology (7th). Elsevier, pg. 577-579.
- Mauldin, EA. Canine Ichthyosis and related disorders of cornification. Vet Clin North Am Small Animal Pract. 2013; 43 (1):89-97
Search terms
test ichtyosis golden retriever, ichthyosis in dogs symptoms, skin disorder, very rare skin condition, dogs resembles fish scales, ichthyosis in puppies, dandruff golden retriever, golden retriever flaky skin, dog dandruff, dog’s skin, flaky skin, dry skin, skin infections, fungal infections, irritated skin, canine ichthyosis, autosomal recessive congenital ichthyosis, skin biopsies, clinical signs, skin barrier function, genetic testing, skin disorder, affected dogs, scaly skin, secondary infections, topical therapy, very rare skin condition, dogs resembles fish scales, skin lesions, veterinary medicine, fish scale disease, golden retrievers, clinical diagnosis, thickened skin, autosomal recessive ichthyosis, congenital ichthyosis, autosomal recessive traits, rare skin condition, skin barrier, dermal inflammation, golden retriever dogs, fungal infections, flaking skin, other disorders, dogs ichthyosis, secondary bacterial, develop ichthyosis, isotretinoin treatment, dogs symptoms, hair loss, stratum corneum, kirk’s small animal dermatology, dog’s skin, ichthyosis in the golden, moderate hyperpigmentation, genetic data, dry skin, greasy flakes, golden retriever ichthyosis, fish scales, severe cases, related disorders, benzoyl peroxide, salicylic acid, young dogs, affected puppies, moisturizing rinses, skin condition, small animal practice, nonepidermolytic ichthyosis, initial presentation, oral retinoid, american bulldog ichthyosis, malassezia dermatitis, histological changes, paw pads, whole body, skin, inguinal region, vet clin north, outer layer, term ichthyosis, prospective study, sebaceous adenitis, outermost layer, american bulldog, ichthyosis, labrador cross, diagnosis, symptoms, dogs, seborrheic dermatitis, premature stop codon, mutations cause autosomal recessive, pnpla1 mutations cause autosomal, cause autosomal recessive congenital, retriever dogs and humans, congenital ichthyosis in golden, west highland white terriers