CLINICAL-FEATURES OF BLISTER BEETLE POISONING IN EQUIDS - 70 CASES (1983-1996)

Objective-To document clinical signs and gross pathologic changes asso ciated with naturally acquired cantharidiasis (blister beetle poisonin g) in equids. Design-Retrospective study. Animals-70 equids with labor atory-confirmed blister beetle poisoning. Procedure-Medical records we re reviewed to obtain history. physical examination findings, feeding practices, and diagnostic test and necropsy results. Results-32 horses and 2 donkeys died from exposure to cantharidin, whereas 36 horses su rvived. Diet content varied, but alfalfa hay was the common component. Onset of signs of disease was rapid. Most equids had signs of gastroi ntestinal tract distress. Six horses had nonspecific neurologic signs. All equids dying from cantharidiasis were in shock terminally, with d uration 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 gastr ic or duodenal ulceration, and 2 had hemorrhage of the urinary bladder mucosa. One horse had cardiac muscle necrosis. Clinicopathologic data available on 10 horses included hypocalcemia, hypomagnesemia, and azo temia. Cantharidin concentrations in urine or pooled gastric-cecal con tents did not always correlate with severity of disease. Clinical Impl ications-Blister beetle poisoning is not universally fatal in equids. Clinical signs are related to the amount of cantharidin ingested. Ever y horse that survived was treated aggressively. In fatal poisonings, g ross lesions may be minimal or inapparent, and diagnosis must be confi rmed by chemical detection of cantharidin in urine, blood, or stomach or cecal contents.