Case report: Herd dermatophilosis outbreak in a desert climate

An acute, rapidly spreading, midsummer outbreak of a dermatological condition in 60 cows on a 3000-cow dairy was accompanied by anorexia and agalactia. Lesions consisted of multiple, 2- to 5-mm thickened and crusted scabs, which revealed inflamed and ulcerated dermis when removed. The herd was located in a desert environment where daytime ambient temperatures often exceeded 100øF. Management practices to cool the cattle included continual application of water misters. Initial on-farm diagnostic attempts were inconclusive so a representative animal was sent to the Washington State University Veterinary Teaching Hospital for evaluation. The dermatological condition clinically resembled dermatophilosis, and diagnostic testing supported this diagnosis. It was concluded that despite environmental conditions that were inconsistent with dermatophilosis, continual misting of cattle resulted in skin maceration facilitating development of the condition. Treatment consisted of daily application of a topical disinfectant and alteration of misting times so cattle would dry between sessions. More severely affected cattle received a one-time parenteral injection of a broad-spectrum antimicrobial. Complete recovery was observed within 14 d of the initiation of treatment and management changes.