A syndrome of hepatogenous photosensitisation, resembling geeldikkop, in sheep grazing Tribulus terrestris.

Two outbreaks of photosensitivity disease occurred in weaner sheep in south western New South Wales during early autumn 1982. In each instance there was a history of access to the annual herb, Tribulus terrestris and both the clinical and pathological findings were consistent with geeldikkop, a major disease in the Republic of South Africa. The prevalence rates of clinical cases were 21 and 37%, while the case fatality rates approached 70%. Clinical signs were dominated by jaundice and photosensitisation. Ochre and khaki discolouration were present in the liver and kidneys, respectively. Histopathologically, the most characteristic lesion was the presence of acicular, cholesterol-like clefts in the lumens of bile ducts and in the cytoplasm of hepatocytes and Kupffer cells. Similar structures were also evident in the lumens of nephrons in association with segmental hyperplasia of the neighbouring tubular epithelium. The possible pathogenesis of the hepatogenous photosensitisation and its resemblance to geeldikkop are discussed.

A study of virus-like particles present in bovine nerve sheath tumours.

The morphology of virus-like particles present in bovine nerve sheath tumours is described, and their origin and significance discussed. Virus-like particles were investigated using transmission electron microscopy and tissue culture. The particles were found in a number of tumours and were present either as aggregates in pseudonuclear inclusions or as budding forms associated with the plasma membrane. The latter were found only in cultured tissue. Although other cellular structures were considered it was thought that the particles represented virus, with those in pseudonuclear inclusions being an intermediate form. Both bovine syncytial virus and oncovirinae were considered as possibilities in the aetiology of the condition.

Incidence of neurofibroma in cattle in abattoirs in New South Wales.

The incidence of neurofibroma in slaughtered cattle in New South Wales during a four-year period is reported. Most of the cases were in adult Hereford females over 5 years old. In 24 of the herds to which neurofibroma cases were traced there was evidence that the disease had previously occurred in the herd. However, the data does not indicate close familial relationship among cases of neurofibroma.