Generalised granulomatous disease in a horse

A 6-year-old gelding was referred with a 3-month history of recurrent fever, inappetance, lethargy and weight loss. On clinical examination major findings were depression, thin condition, thrombophlebitis, nodules on the scrotal skin, leukocytosis, hyperfibrinogenaemia and hyperglobulinaemia. Pleural fluid and areas of lung consolidation were seen on ultrasonographic examination of the thorax. A diagnosis of chronic respiratory disease was made. Initially there was a response to antibiotic therapy but the horse was presented 3 months later with continued weight loss, recurrent fever and multifocal skin lesions, characterised by scales, crusts and nodules, affecting the nasal bridge, jugular grooves, ventral neck, withers, scrotum, prepuce, and medial gaskins. Histological evaluation of skin biopsies indicated a granulomatous reaction. On ultrasonographic examination of the thorax multiple hypoechoic lesions consistent with granulomas were seen in both lungs. A diagnosis of generalised granulomatous disease was made. The horse was euthanased at the owner's request. On necropsy examination the main findings were multiple nodules of fibrotic granulomatous inflammation in the lung, heart, liver, gastrointestinal tract and mesenteric lymph nodes, supporting the diagnosis of generalised granulomatous disease.