Veterinary Medicine - August 2007 - (Page 515)

off with mild soap and water. Side effects include localized redness, crusting, burning, and pruritus at the site of application. In dogs with more extensive lesions of solar dermatitis, the expense of Aldara (about $245 for a box of 12 individual 250-mg single-use packets) may preclude its use. Monitor for disease progression Even with future sun avoidance, prior skin damage can still progress to skin neoplasia months or years after exposure (Figure 7). Once skin neoplasia has occurred, aggressive surgical resection or laser therapy should be performed. In addition, if large or invasive masses are present, screening for metastasis to draining lymph nodes and internal structures is necessary. O REFERENCES 1. Scheuplein RJ. Mechanism of temperature regulation in the skin. In: Fitzpatrick TB, Eisen AZ, Wolff K, et al., eds. Dermatology in general medicine. 3rd ed. New York: McGraw-Hill Book Co, 1987;347-357. 2. Scott DW, Miller WH, Griffin CE. Muller and Kirk’s small animal dermatology. 6th ed. Philadelphia, Pa: WB Saunders Co, 2001;1073-1080. 3. Bernhard JD, Pathak MA, Kochevar IE, et al. Abnormal responses to ultraviolet radiation. In: Fitzpatrick TB, Eisen AZ, Wolff K, et al., eds. Dermatology in general medicine. 3rd ed. New York: McGraw-Hill Book Co, 1987;1481-1507. 4. Freedberg IM, Eisen AZ, Wolff, K, et al. Fitzpatrick’s dermatology in general medicine. 5th ed. New York: McGraw-Hill Book Co, 1999. 5. Hruza LL, Pentland AP. Mechanisms of UV-induced inflammation. J Invest Dermatol 1993;100:35S-41S. 6. Kimura T, Doi K. Responses of the skin over the dorsum to sunlight in hairless descendants of Mexican hairless dogs. Am J Vet Res 1994;55:199-203. 7. Hargis AM, Lewis TP. Case report: Full thickness cutaneous burn in black-haired skin on the dorsum of the body of a Dalmatian puppy. Vet Dermatol 1999;10:39-42. 8. Mason K. Actinic dermatosis in dogs and cats, in Proceedings. Annu Meet Eur Soc Vet Dermatol Eur Coll Vet Dermatol 1997;67. 7. The same dog as in Figures 1 and 6 after six weeks of antibiotic therapy and three months of sun avoidance. Although scarring is still present, the prior lesions of erythema and bullae have resolved. However, note the persistent scaly, erythematous erosive lesion on the prepuce, which is likely a precancerous or early cancer lesion. A biopsy is indicated. A2,14) such as acitretin at a dosage of 0.5 to 1 mg/kg orally every 24 hours.2 The potential side effects of retinoids include keratoconjunctivitis sicca, mucocutaneous lesions, vomiting, diarrhea, musculoskeletal abnormalities, triglyceride elevations, and hepatotoxicity,2,11 so careful monitoring is necessary. Additionally, retinoids are highly teratogenic.2 A positive clinical response to retinoids should be noted within four to six weeks. At that point, the frequency of medication can be reduced to an alternate-day basis.11 Vitamin A Because of the expense of retinoids, oral vitamin A has been used anecdotally for canine solar dermatitis, but controlled clinical trials and published studies elucidating doses or side effects are not available. The dosage of oral vitamin A in dogs should not exceed 400 IU/kg/day, and patients should be monitored for the same potential side effects as listed for retinoids.2 Prior skin damage can progress to skin neoplasia months or years after exposure. 9. Medleau LM, Hnilica KA. Small animal dermatology: A color atlas and therapeutic guide. Philadelphia, Pa: WB Saunders Co, 2005. 10. Gross TL, Ihrke PJ, Walder EJ, et al. Skin diseases of the dog and cat: Clinical and histopathologic diagnosis. 2nd ed. Oxford: Blackwell Science, 2005;399-401. 11. Rosenkrantz WS. Solar dermatitis. In: Griffin CE, Kwochka KW, MacDonald JM, eds. Current veterinary dermatology. St. Louis, Mo: Mosby-Year Book, 1993;309. 12. Kimura T, Doi K. Protective effects of sunscreens on sunburn and suntan reactions in cross-bred Mexican hairless dogs. Vet Dermatol 1994;5:175-187. 13. Mason KV. The pathogenesis of solar induced skin lesions in bull terriers, in Proceedings. Annu Member Meet Am Acad Vet Dermatol Am Coll Vet Dermatol 1987;12. 14. Keller KL, Fenske NA. Use of vitamins A, C, and E and related compounds in dermatology: a review. J Am Acad Dermatol 1998;39:611-625. 15. Alomar A, Bichel J, McRae S. Vehicle-controlled, randomized, double-blind study to assess safety and efficacy of imiquimod 5% cream applied once daily 3 days per week in one or two courses of treatment of actinic keratoses on the head. Br J Dermatol 2007;157:133-141. 16. Lebwohl M, Dinehart S, Whiting D et al. Imiquimod 5% cream for the treatment of actinic keratosis: results from two phase III, randomized, double-blind, parallel group, vehicle-controlled trials. J Am Acad Dermatol 2004;50:714–721. 17. Szeimies RM, Gerritsen MJ, Gupta G, et al. Imiquimod 5% cream for the treatment of actinic keratosis: results from a phase III, randomized, double-blind, vehicle-controlled, clinical trial with histology. J Am Acad Dermatol 2004;51:547–555. 18. Korman N, Moy R, Ling M, et al. Dosing with 5% imiquimod cream 3 times per week for the treatment of actinic keratosis: results of two phase 3, randomized, double-blind, parallel-group, vehicle-controlled trials. Arch Dermatol 2005;141:467–473. Imiquimod Actinic keratosis in people may be helped by using a topical immunomodulator such as imiquimod (Aldara—3M Pharmaceuticals), but studies in dogs are lacking. Imiquimod’s mechanism of action involves inducing local antitumor and antiviral immune responses by stimulating lymphocytes, dendritic cells, and macrophages. In people, imiquimod cream is applied to affected areas two to three times a week for four to 16 weeks.15-18 According to the Aldara package insert, the size of the treated area should be no larger than 2 x 2 in, and the cream should not be used near the eyes, lips, or nostrils. The cream is left on the skin for eight hours before being washed VETERINARY MEDICINE August 2007 515

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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