Dermatophilosis compatible with Dermatophilus spp. in a rehabilitating brown brocket deer fawn (Subulo gouazoubira)

Abstract Dermatophilosis is an exudative bacterial dermatitis generally associated with Dermatophilus congolensis , widely described in domestic ruminants and cervids from the Northern Hemisphere, but poorly documented in Neotropical cervids. To describe a case of dermatophilosis compatible with Dermatophilus spp. in a female brown brocket fawn ( Subulo gouazoubira ) undergoing rehabilitation in Rio Grande do Sul, Brazil. Clinical evolution, cytological and Gram-staining findings, ancillary diagnostic tests, therapeutic management and outcome were evaluated. Skin lesion material was examined by Giemsa-stained cytology and Gram staining. Skin scrapings and fungal culture were also performed. Treatment consisted of intramuscular long-acting penicillin, daily topical antisepsis with 1% povidone-iodine, dermatological ointment and strict environmental management. At admission, the animal presented with bilateral purulent ocular discharge, moderate dehydration and a low tick burden, with no evident skin lesions. After 12 days of hospitalization, alopecic, dry, erythematous and crusted lesions developed in the nasal region, distal limbs and pinnae. Cytology revealed marked suppurative inflammation associated with a high bacterial load, including structures arranged in parallel rows forming the characteristic “railroad track” pattern. Gram staining revealed similarly arranged Gram-positive structures compatible with Dermatophilus spp. Skin scrapings and fungal culture were negative. Because bacterial culture, histopathology and molecular assays were not performed, the diagnosis remained presumptive. Progressive lesion regression, hair re-growth and complete clinical recovery were observed. Dermatophilosis should be considered in the differential diagnosis of crusting dermatopathies in Neotropical cervids, and cytology may be a useful initial diagnostic tool in wild animals undergoing rehabilitation.