Malignant catarrhal fever in farmed Rusa deer (Cervus timorensis). 1. Clinico-pathological observations.

A sporadic fatal disease is described in 7 Rusa deer (Cervus timorensis) from 5 deer farms in Victoria. Bilateral ophthalmia and wasting were the most significant signs in a clinical course varying from 4 to 34 days. Bilateral hypopyon, peripheral corneal opacities and interstitial mononuclear cell infiltration of the renal cortex with pronounced mural thickening and dilatation of vessels at the cortico-medullary junction were the only consistent lesions. Haemorrhagic ileitis, colitis and typhlitis were the major lesions in two deer that died 4 and 6 days after onset of clinical disease. Ecchymotic haemorrhages and sub-serosal haematomas on the intestines and mesentery were the main finding in cases with a longer clinical course. Other gross lesions varied between cases. The most significant histological lesion was fibrinoid necrotising vasculitis with adventitial lymphoid cell infiltration characteristic of bovine malignant catarrhal fever. Mucosal erosions seen in protracted cases of this disease were associated with lymphoid cell infiltration into foci of degenerating epithelial cells. In many lymph nodes there was severe follicular necroses. In chronic cases extensive proliferation of lymphoblastoid cells was seen in the parafollicular cortex and medullary sinuses of nodes which also showed discrete follicular necrosis.