Veterinary Medicine - August 2007 - (Page 514)

Canine solar dermatitis O P E E R - R E V I E W E D 4. More subtle solar-induced lesions of patchy erythema, alopecia, and fibrosis with comedones and scattered small bullae on the dorsolateral trunk of an American bulldog. form a biopsy immediately to expedite treatment. Biopsy can be performed by administering lidocaine locally and obtaining multiple skin punch or excisional biopsy samples of different lesions (Figure 6). Since some of the histologic changes can be seen with other conditions such as bacterial folliculitis, one key to a definitive histologic diagnosis is to include a complete history with the biopsy submission form, including signalment, degree of sun exposure, distribution of lesions, clinical description of lesions, response or lack of response to prior therapies, and current medications (including glucocorticoids) that could affect the histologic findings. Requesting a full histologic description and seeking interpretation by a veterinary dermatopathologist are recommended. In early cases of solar dermatitis, histologic examination shows variable degrees of perivascular dermatitis, folliculitis, and dermal fibrosis or increased collagen accumulation or collagen damage. Solar elastosis (linear bands of degenerated basophilic elastin accumulation arranged parallel to the skin surface) may be seen. In chronic cases, histologic examination may show follicular cysts, pyogranulomatous inflammation, and precancerous actinic keratosis or neoplastic cells.2,9,10 TREATMENT The best treatment for canine solar dermatitis is prevention. Educate owners of at-risk dogs about the need for sun avoidance starting at a young age. Also tell owners of affected and at-risk dogs that oral and topical medications cannot replace sun avoidance in treating and preventing solar dermatitis. Reduce sun exposure 5. Solar dermatitis on the inguinal area of an American bulldog. After years of sun damage, a large squamous cell carcinoma has formed. The main treatment recommendation for solar dermatitis is restricting sun exposure by keeping the dog indoors during the day, especially between 9 a.m. and 3 p.m., which is considered the most intense UV radiation time.2 If some sun exposure is unavoidable, then frequent (twice a day11) topical application of a waterproof, high-SPF sunscreen (a product with an SPF > 15 absorbs more than 92% of UVB rays12) that is labeled as safe for babies and that protects against UVA and UVB rays is indicated.2 Having the dog wear a T shirt may help decrease sun exposure2; however, it is often impossible to cover all at-risk areas of the skin. A dog sun suit is available at www.designerdogwear.com, or clients may be able to sew a sun suit for their pets by using sunblocking fabric available for people. Beta-carotene or acetretin To decrease sun damage, beta-carotene (30 mg orally b.i.d. for 30 days then 30 mg/day for life) in combination with anti-inflammatory doses of oral glucocorticoids may be effective in early cases.2,13 Skin damage may also be reduced by administering oral retinoids (synthetic vitamin A analogues, which are more potent and less toxic than vitamin 6. Inguinal erythema, scarring, and furunculosis caused by chronic sun damage in the same dog as in Figure 1. The circled areas indicate biopsy sites. 514 August 2007 VETERINARY MEDICINE http://www.designerdogwear.com

Table of Contents Feed for the Digital Edition of Veterinary Medicine - August 2007

Contents A Veterinary Medicine Interview Veterinary Voices Idea Exchange Diagnosis and Treatment of Solar Dermatitis in Dogs Diagnostic Imaging for Linear Foreign Bodies in Cats Overcoming the Diagnostic and Therapeutic Challenges of Canine Immune-Mediated Thrombocytopenia Ophthalmic drugs: What’s new? CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - August 2007

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