Canine eosinophilic furunculosis.

Background: The eosinophilic furunculosis is an uncommon skin disease that affects young dogs aged between two and five years. Sex predilections are not noted. Most reported cases have been in large breeds with abundant access to the outdoors like public gardens and parks. The exact pathogenesis remains unknown but the pattern of lesions development suggests involvement reaction to insect bites and arthropods. The time between contact with the agent and the appearance of lesions is short, often less than 24 h. The skin lesions appear suddenly in the face, usually on the dorsal muzzle and/or periocular region, pinnae and lips. More rarely on the trunk, chest and legs and it is characterized by predominantly hemorrhagic ulcers with edema. Pustules, nodules and plaques rapidly fistulate and drain serosanguinous exudates. Pruritus is variable, but may be severe. Severely affected dogs may be febrile, lethargic and anoretic. Peripheral blood eosinophilia is seen in the majority of cases. Clinical differential diagnosis include demodicosis, dermatophytosis, nasal deep bacterial folliculitis and furunculosis, pemphigus foliaceus, pemphigus erythematosus and drug reactions. None of these diseases share the fulminant rapid onset of eosinophilic furunculosis. The diagnosis is based on history, clinical signs, cytology and skin biopsies. The treatment involves oral steroids until complete remission of lesions and the antibiotic therapy is indicated in cases of associated bacterial infection. Case: The patient was a 4-year-old, male Pit Bull dog attended in a small animal clinic in Niteroi-Rio de Janeiro, which presented ulcerated, exudative lesions on the dorsal muzzle and right leg. After sedation, clinical examination was performed and an exudate was collected from the ulcerated skin lesion for cytopathological analysis. The slide containing the lesion impression was stained by a quick panoptic method. In order to collect samples, the dog was sedated with a combination of ketamine hydrochloride and acepromazine and a skin fragment was collected from the nasal bridge lesion with a 6 mm punch after local anesthesia with 2% lidocaine hydrochloride. The specimen was fixed in 10% buffered formalin and sent for histopathological analysis. The cytopathological exam revealed a marked eosinophilic inflammation. Histopathological examination revealed ulcerated skin. The epidermis was moderately acanthotic with mild espongiosis and the dermis was characterized by intense eosinophilic folliculocentric inflammations. An extensive folicular rupture, eosinophilic mural foliculitis were presented and PAS staining did not identify fungal structures. Oral prednisone (2 mg/Kg) at 24h intervals was prescribed until complete remission of the lesions. After fifteen days of glucocorticoids therapy, involution of the skin lesions was observed by physical examination and was also reported by the owner. Discussion: The eosinophilic furunculosis is an acute, severe predominantly facial disease of outdoor dogs, which occurrence is rare. The diagnosis and treatment of this disease are frequently neglected because they are not included in the differential diagnosis of diverse cutaneous infections. In view of the scarcity of reports and to alert veterinarians that the disease should be included in the differential diagnosis with other bacterial diseases, this report described a case of canine eosinophilic furunculosis.