Ingestion of Swainsona spp. by grazing livestock results in a chronic disease characterized by neurological disturbances and intense vacuolation of cells in most organs. Experiments were carried out using Swainsona canescens and evidence is presented to show that tissues from affected animals contain high levels of mannose-rich oligosaccharides and that the plant contains an inhibitor of lysosomal alpha-mannosidase. It is concluded that ingestion of Swainsona induces a lysosomal storage disease, biochemically and morphologically similar to genetically determined mannosidosis. The role of this process in relation to Swainsona toxicosis is discussed.

Animals↗

PubMedDate not supplied

Myelin oedema, optic neuropathy and retinopathy in experimental Stypandra imbricata toxicosis.

Rats experimentally poisoned with the toxic plant Stypandra imbricata developed acute oedema of central and peripheral myelin and extensive axonal degeneration in the optic nerves. The oedema developed with vacuolation and splitting of myelin lamellae at the intraperiod line. Following recovery from acute intoxication, myelin oedema resolved after 6 to 12 weeks, but severe retinal degeneration and optic nerve atrophy remained. Morphological abnormalities in glial cells and axons were only found in the optic nerves. It was concluded that there is probably also a direct toxic effect on the axons of the optic nerve and the photoreceptor cells of the retina. The chemical nature of the toxin remains to be defined but the marked similarity of its toxic effects to those of hexachlorophene are noted.

Acute Disease↗

PubMedDate not supplied

Naturally-occurring neonatal canine herpesvirus infection.

The detailed clinical and epidemiological history and the pathology of neonatal canine herpesvirus (CHV) disease in a naturally infected litter of pups is reported. Herpesvirus was isolated from the brain, lung, liver, spleen, kidney and intestine of one of the affected litter which died on day 10 after whelping. The isolation of virus correlated with the distinctive gross and histological changes in these organs. Herpesvirus was isolated also from the anterior vagina of the bitch 18 days after whelping --a finding which may be of significance in the epidemiology of the natural disease.

Animals↗