Clinical features of blister beetle poisoning in equids: 70 cases (1983-1996)
Helman, R.G.; Edwards, W.C.
Journal of the American Veterinary Medical Association 211(8): 1018-1021
1997
ISSN/ISBN: 0003-1488 PMID: 9343547 Document Number: 477674
Medical records of 68 horses and 2 donkeys with blister beetle [Meloidae] poisoning were reviewed. 32 horses and 2 donkeys died from exposure to cantharidin, whereas 36 horses survived. Diet content varied, but alfalfa hay was the common component. Onset of signs of disease was rapid. Most equids had signs of gastrointestinal tract distress. Six horses had non-specific neurological signs. All equids dying from cantharidiasis were in shock terminally, with duration of clinical signs ranging from 3 to 18 hours. Six horses that died had no gross lesions, whereas 14 had mild to moderate erythema of gastric, small intestinal, or colonic mucosa. Only 2 horses had gastric or duodenal ulceration, and 2 had haemorrhage of the urinary bladder mucosa. One horse had cardiac muscle necrosis. Clinicopathological data available on 10 horses included hypocalcaemia, hypomagnesaemia, and azotaemia. Cantharidin concentrations in urine or pooled gastric-caecal contents did not always correlate with severity of disease. It is concluded that blister beetle poisoning is not universally fatal in equids. Clinical signs are related to the amount of cantharidin ingested. In fatal poisonings, gross lesions may be minimal or inapparent, and diagnosis must be confirmed by chemical detection of cantharidin in urine, blood, or stomach or caecal contents.