EXPERIMENTAL POISONING OF HORSES AND CATTLE WITH SWAINSONA CANESCENS VAR HORNIANA

Abstract

Horses and cattle fed swainsona over 8-10 wk lost condition and became uncoordinated and hypersensitive. Histological examination of tissues from affected animals revealed characteristic changes of widespread cellular vacuolation and axonal spheroids in the CNS. Cattle withdrawn from the toxic plant after being fed for varying periods up to 8 wk returned to normal. Serum .alpha.-mannosidase activity declined significantly in cattle during the test period, but in horses the activity rose. Serum alkaline phosphatase levels increased significantly in cattle but not in horses. A similarity was noted in clinical signs of the disease in horses and those seen in Indigofera linnaei poisoning (Birdsville disease). Differential diagnosis can be made by botanical observations and by an increased frequency of vacuolated lymphocytes in the blood in swainsona poisoning.