Equine allergic skin diseases: Clinical consensus guidelines of the World Association for Veterinary Dermatology.

BACKGROUND: Allergic skin diseases are common in horses worldwide. The most common causes are insect bites and environmental allergens. OBJECTIVES: To review the current literature and provide consensus on pathogenesis, diagnosis, treatment and prevention. MATERIALS AND METHODS: The authors reviewed the literature up to November 2022. Results were presented at North America Veterinary Dermatology Forum (2021) and European Veterinary Dermatology Congress (2021). The report was available to member organisations of the World Association for Veterinary Dermatology for feedback. CONCLUSIONS AND CLINICAL RELEVANCE: Insect bite hypersensitivity (IBH) is the best characterised allergic skin disease. An immunoglobulin (Ig)E response against Culicoides salivary antigens is widely documented. Genetics and environmental factors play important roles. Tests with high sensitivity and specificity are lacking, and diagnosis of IBH is based on clinical signs, seasonality and response to insect control. Eosinophils, interleukin (IL)-5 and IL-31 are explored as therapeutic targets. Presently, the most effective treatment is insect avoidance. Existing evidence does not support allergen-specific immunotherapy (ASIT) using commercially available extracts of Culicoides. Hypersensitivity to environmental allergens (atopic dermatitis) is the next most common allergy. A role for IgE is supported by serological investigation, skin test studies and positive response to ASIT. Prospective, controlled, randomised studies are limited, and treatment relies largely on glucocorticoids, antihistamines and ASIT based on retrospective studies. Foods are known triggers for urticaria, yet their role in pruritic dermatitis is unknown. Recurrent urticaria is common in horses, yet our understanding is limited and focussed on IgE and T-helper 2 cell response. Prospective, controlled studies on treatments for urticaria are lacking. Glucocorticoids and antihistamines are primary reported treatments.

Pilot evaluation of Enterococcus faecium SF68 as adjunctive therapy for oclacitinib-responsive adult atopic dermatitis in dogs.

OBJECTIVE: To evaluate the adjunctive effect of supplementation with Enterococcus faecium SF68 (FortiFlora; Purina Pro Plan Veterinary Diets) on oclacitinib (Apoquel, Zoetis) dose reduction, while maintaining or reducing the Pruritus Visual Analog Score and Canine Atopic Dermatitis Extent and Severity Index values in client-owned adult dogs with environmental atopic dermatitis. MATERIALS AND METHODS: Enrolled dogs had exhibited control of atopic dermatitis on oclacitinib for at least 6 months before, and continuing throughout, the study. Dogs with non-seasonal pruritus were blindly randomised to receive either SF68 (1×108 colony forming units/g orally twice daily) or placebo for 12 weeks. After 8 weeks of supplementation, oclacitinib dose was decreased by approximately 25%, aiming to maintain and reduce the clinical disease scores. RESULTS: Supplementation with SF68 was associated with no difference in oclacitinib dose reduction versus placebo in 21 client-owned dogs with atopic dermatitis. Clinical disease scores were not different between groups at study completion. CLINICAL SIGNIFICANCE: Further larger-scale studies are warranted to investigate optimal strain(s), dosing and duration of probiotic supplementation as an adjunctive strategy in management of canine atopic dermatitis.

The effect of a spot-on formulation containing polyunsaturated fatty acids and essential oils on dogs with atopic dermatitis.

Recent studies have shown that immunological aberrations and epidermal barrier defects could be important in the pathogenesis of canine atopic dermatitis (CAD) and that oral polyunsaturated fatty acids (PUFAs) might influence the epidermal barrier. The aim of this study was to evaluate the effects of a spot-on formulation containing PUFAs and essential oils on pruritus and lesions caused by CAD. Forty-eight privately owned dogs of different breeds, ages and genders diagnosed with atopic dermatitis were included in a randomized, double-blinded, placebo-controlled, multicentre clinical trial. Dogs were treated with a spot-on formulation containing PUFAs and essential oils or placebo on the dorsal neck once weekly for 8weeks. Before and after the study, CAD extent and severity index-03 (CADESI-03) and pruritus scores were determined by veterinarians and owners, respectively. There was significantly more improvement in CADESI-03 and pruritus scores in the treatment group than in the placebo group (P=0.011 and P=0.036, respectively). Additionally, more dogs improved by at least 50% in CADESI-03 and pruritus scores in the treatment group than in the placebo group (P=0.008 and P=0.070, respectively). No adverse reactions were observed. The topical preparation containing PUFAs and essential oils was a safe treatment and beneficial in ameliorating the clinical signs of CAD.

Evaluation of the potential use of adipose-derived mesenchymal stromal cells in the treatment of canine atopic dermatitis: a pilot study.

Stem cells and their potential therapeutic uses in human and veterinary medicine have generated considerable interest. These cells have a number of potentially unique immunologic properties; most notable are their reported regenerative and antiinflammatory capabilities. The aim of this prospective pilot study was to evaluate the efficacy of intravenously administered autogenous adipose-derived mesenchymal stem cells (AD-MSCs) in the treatment of canine atopic dermatitis. AD-MSCs administered intravenously at a dose of 1.3 million cells/kg did not significantly reduce the clinical signs of canine atopic dermatitis or the owner-assessed pruritus level.

Onychectomy as a therapy for symmetric claw and claw fold disease in the dog.

Chronic onychodystrophies are a group of diseases that are frustrating and potentially expensive to manage. Despite appropriate diagnostics, an underlying etiology may not be identified. Long-term therapy may result in resolution or remission; however, relapses are common. In many cases, the disease persists in the face of appropriate therapy. Seven dogs with chronic onychodystrophies were treated with onychectomies. Treatment resolved the clinical signs for a follow-up period of four months to six years.

Systemic/topical therapy.

Hopefully, the practitioner has obtained a basic broader knowledge of the options available for topical and systemic equine dermatologic therapy. There are many topical and systemic agents that can aid in the treatment of specific skin disease and there are safer alternatives to glucocorticoid therapy. Because equine dermatology is still in its infancy, there is still much to be learned. The practitioner is encouraged to pay close attention to this specialty because it will continue to evolve rapidly.

Factors associated with and prevalence of high Malassezia pachydermatis numbers on dog skin.

The prevalence of cutaneous Malassezia spp was evaluated in a semiquantitative fashion at 3 sites on 98 dogs examined because of various dermatoses. Thirty (10.2%) of the sites and 19 (19.4%) of the dogs had Malassezia spp amounts higher than that found on grossly normal skin. The prevalence of higher than normal amounts did not correlate significantly with sample site, sex, or age. The factors associated with an increased prevalence of increased Malassezia spp counts were seborrheic dermatitis, recent antibiotic treatment, and breed.

Malignant melanoma of the conjunctiva in a cat.

A conjunctival melanoma was diagnosed in an adult domestic cat. The neoplasm was excised without further complications. It is important to differentiate conjunctival melanoma from other types of pigmented ocular neoplasia. In man, conjunctival melanomas are often malignant tumors with potential for metastatic behavior. Although this neoplasm had histologic features of malignancy, no evidence of local recurrence or metastasis has been apparent during the 11-month follow-up period.