Synthetic retinoids in veterinary dermatology

Efficient Topical Treatment of Canine Nodular Sebaceous Hyperplasia with a Nitric Acid and Zinc Complex Solution

Nodular sebaceous gland hyperplasia in the often middle-aged to old dog is a common, benign proliferation that results in exophytic, pink to yellow, alopecic, and often multilobulated nodules. Removal is usually carried out by surgical excision. As many old dogs have comorbidities that increase the risk of anesthesia, a topical treatment is warranted. We hypothesized that the application of a solution containing nitric acid, zinc, copper, and organic acids (Verrutop®), would be a safe and efficient way to treat these nodules. Eleven dogs with a total of 29 nodules, grossly compatible with nodular sebaceous gland hyperplasia, were included in the study. Eighteen of the nodules were treated; 11 were left untreated. No anesthesia or sedation was needed. Four weeks after one application, 17/18 treated nodules had decreased by 100% in volume. There was a statistically significant difference in percentual volume change between the treated and untreated nodules from day 0 to day 28 (p < 0.0001). No serious side effects were noted. Sebaceous hyperplasia cannot always be distinguished grossly from sebaceous tumors. Cytological evaluation can be helpful, and in cases of deviant macroscopic features, local recurrence, or more aggressive behavior, the appropriate intervention would be to biopsy or excise the nodule for histopathology. Topical application of Verrutop® is an easy, low-cost, and efficient way to remove canine sebaceous gland hyperplasia with minimal side effects in cases where surgery and anesthesia are not desired.

Isotretinoin treatment of 12 dogs with epitheliotropic lymphoma

BACKGROUND

Epitheliotropic lymphoma is an uncommon cutaneous malignancy of T lymphocytes. Limited information is available regarding the treatment and outcome of dogs with this disease.

OBJECTIVES

To evaluate the treatment outcome and toxicity profile of isotretinoin in dogs with epitheliotropic lymphoma.

ANIMALS

Twelve dogs with a diagnosis of epitheliotropic lymphoma were included.

MATERIALS AND METHODS

A medical database was searched for dogs diagnosed with epitheliotropic lymphoma and treated with isotretinoin between 2010 and 2021. Diagnosis, treatment details and tumour response were recorded for 12 dogs.

RESULTS

All lesions resolved in four of 12 (33%) treated dogs. Lesions visibly improved in a further three dogs, giving a response rate of 58%. Two dogs' lesions remained unchanged and three progressed despite therapy. Adverse effects occurred in three dogs (25%), all of which were rapidly resolving or not affecting quality of life.

CONCLUSION

Isotretinoin treatment was a well-tolerated and effective treatment for canine epitheliotropic lymphoma.

Isotretinoin Treatment for Autosomal Recessive Congenital Ichthyosis in a Golden Retriever

Ichthyoses are hereditary cornification disorders that manifest with abnormal differentiation and desquamation of keratinocytes in a form of generalized dry and scaly skin. In golden retriever dogs, autosomal recessive congenital ichthyosis (ARCI) has been associated with mutations in the PNPLA 1 gene. In human medicine, isotretinoin is frequently used to treat ARCIs. The aim of this study was to investigate the clinical and histological effects of isotretinoin on ARCI in a golden retriever dog with confirmed mutation in the PNPLA 1 gene. Clinical examination, blood analysis and histopathological examinations were conducted before and after 90 days of isotretinoin therapy. The clinical and histopathological findings indicate that treatment with oral isotretinoin was effective in improving ichthyosis without any side-effects.

Clinical response to isotretinoin and interferon-α of two dogs with cutaneous epitheliotropic T-cell lymphoma: a case report

BACKGROUND

There is no specific therapy for cutaneous epitheliotropic T-cell lymphoma (CETL). The administration of retinoids in conjunction with interferon-α (IFN-α) in CETL has not been reported in dogs.

CASE PRESENTATION

Two dogs (Shih tzu and Miniature pinscher) presented with multiple nodular skin lesions. Histopathological examination revealed diffuse infiltrations of lymphocytes in the epidermis and dermis, with a CD3-positive immunophenotypic profile. Based on the clinical and histopathological examination, CETL was diagnosed. Both dogs were treated with isotretinoin in combination with IFN-α and showed clinical improvement with complete or partial remission. The disease in these dogs was well-controlled for more than 264 days of overall median survival time without any additional clinical signs after initiation of the treatment. In both the cases, the dogs were followed up for 27 months, and 10 months without any evidence of recurrence or metastasis, respectively.

CONCLUSIONS

We describe the clinical efficacy of isotretinoin combined with IFN-α in 2 dogs with CETL. Long-term management with isotretinoin combined with IFN-α was effective in treating CETL in these cases.

Scaling dermatosis in three dogs associated with abnormal sebaceous gland differentiation

BACKGROUND

Abnormal sebaceous gland differentiation, so-called 'sebaceous gland dysplasia', is a rare condition described in the dog and the cat. Although little is known about this condition, it is thought that a genetic defect causes abnormal sebaceous gland development. Clinically, this condition occurs in young cats and dogs and is characterized by variable degrees of adherent scale, hair casts, poor coat quality and hypotrichosis.

HYPOTHESIS/OBJECTIVE

Here, we describe the clinical presentation and treatment of three adult dogs with abnormal sebaceous gland differentiation.

ANIMALS

Three adult dogs presented with a keratinization defect characterized by progressive scaling, hair casts, dull, dry, brittle hair coat and hypotrichosis beginning in puppyhood to early adulthood.

METHODS

Multiple 6 mm punch skin biopsy samples were obtained from each dog. Treatments included various topical keratomodulatory agents, oral essential fatty acids and oral vitamin A.

RESULTS

Histologically, all sebaceous glands were small and composed of a mixture of irregularly clustered basal reserve cells and mature sebocytes. With therapy, two of the dogs showed moderate to marked clinical improvement in scaling, hair casts and hair coat quality.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although rare, 'sebaceous gland dysplasia' should be considered in cases where a primary keratinization defect is suspected. Given that abnormal sebaceous differentiation is a structural defect of the skin, treatment must be maintained and is aimed at ameliorating the clinical signs rather than curing the disease.

Familial ichthyosiform keratoderma in newly out-of-pouch Bennett's wallabies (Macropus rufogriseus) and report of two cases

Primary inherited disorders of cornification in veterinary medicine are uncommon and rarely reported. Herein described is a unique syndrome associated with keratoderma that occurred in two Bennett's wallaby siblings (Macropus rufogriseus), and was characterized by profound thickening of the pad skin of all feet, generalized scaling of haired skin, and death within 7 weeks of out-of-pouch experience. The male also had depressed serum zinc levels. In addition, the male had, on electron microscopic exam of his skin, the presence of abnormal lipid deposits within the stratum corneum and stratum granulosum. The combination of clinical features and electron microscopic findings strongly suggests a syndrome analogous to harlequin ichthyosis or lamellar ichthyosis in humans.

Isotretinoin in the treatment of multiple benign pilomatrixomas in a mixed-breed dog

An 18-month-old cross-breed dog developed multiple skin nodules, which over 8 months had increased in size and number. Biopsy samples were submitted for histopathological examination and revealed multiple benign pilomatrixomas. The dog was treated with 1 mg kg(-1) isotretinoin daily, which led to a stabilization of the size and number of the lesions. Attempts to lower the dosage to an every other day regimen led to an increase in the nodules' size and number. Monthly complete blood count and chemistry tests and Schirmer tear tests were performed to monitor any adverse effects of the retinoid treatment. No adverse effects were noted. To the authors' knowledge, this is the first report of multiple pilomatrixomas arising in a young dog and successfully controlled with oral retinoids.

Therapy for feline dermatoses

This article compiles information on various therapies used in feline dermatology. Information on the following therapeutic agents and devices is discussed: antibiotics, antifungals, antileprosy drugs, antiparasiticides, antivirals, antihistamines, behavior modification drugs, fatty acids, progestogens, steroids, immunomodulating drugs, chemotherapeutic/immunosuppressive agents, retinoids, mechanical devices, hyposensitization, immunotherapy, food elimination trials, hypoallergenic diets, and miscellaneous topical agents such as polyhydroxydine solution, tar, and benzocaine-containing creams.

Facial, pedal, and other regional dermatoses

This article discusses disorders of the head and face, including feline acne, solar dermatoses, pruritus of the head and neck, and nodular or ulcerative dermatoses of the head. Disorders of the pinna, otitis externa, and nasal diseases are highlighted. In addition, a discussion of pododermatitis and diseases of the claws and ungual fold is presented. Miscellaneous regional dermatoses include midline ulcerative dermatitis, stud tail, and vaccine-induced lesions.