Suspected sheep-associated malignant catarrhal fever in a zero-grazed dairy herd in Kenya

An outbreak of a disease characterised by very high mortality occurred in a group of nine calves (1B4 months old) in a zero-grazing unit 2-3 weeks aft er an introduction of an apparently healthy alien sheep into the calf pen. Five of the six calves which contracted the disease died. The main clinical signs observed were marked depression, persistently high body temperature (40,5-41,5 degrees C), copious mucopurulent nasal and ocular discharges, dy spnoea, bilateral keratoconjunctivitis with corneal opacity, enlargement of the superficial lymph nodes and marked erythema and/or superficial erosion s of the buccal mucosae. At necropsy there were lesions in the upper respir atory and digestive tracts, lymph nodes, brain, eyes, liver, kidneys and th e urinary bladder. The lesions were histopathologically characterized by fi brinoid vasculitis which was accompanied by lymphocytic infiltration in the parenchyma of the affected tissues. Based on the evidence of contact betwe en the calves and the recently introduced foreign sheep, the characteristic clinical signs and histopathological findings, a diagnosis of sheep-associ ated malignant catarrhal fever was made.