Experimental cantharidiasis in the horse
Shawley, R.V.; Rolf, L.L.
American Journal of Veterinary Research 45(11): 2261-2266
1984
ISSN/ISBN: 0002-9645 PMID: 6441486 Document Number: 238238
Crystalline cantharidin in an alfalfa cake or in aqueous suspension was given to 8 horses at a dosage level of 450-489 .mu.g/kg body wt (group 1) and 2 horses at a dosage level of 720 .mu.g/kg (group 2) via nasogastric tube. Both group 2 horses and 1 group 1 horse died. Horses were evaluated at 6-h intervals for 36 h and then again at postcantharidin 48 h. Data evaluation consisted of a comparison of the nonsurvival and survival data to one another and their respective base-line values at each sampling period, irrespective of the route of administration and dosage level. Consistent findings in both groups included significant (P .ltoreq. 0.05) increases in cardiac rate, respiratory rate and rectal temperature and decreases in total serum Ca, serum Mg and K concentrations during at least one 6-h period. Ca and Mg concentrations were still significantly (P .ltoreq. 0.05) depressed at postcantharidin h 48, although other electrolytes and physiologic values had returned to base line. Arterial O2 tension, total protein, serum creatine kinase, arterial CO2 and plasma bicarbonate were depressed in surviving horses during 1 or more periods. The most consistent clinical signs were anorexia and depression; severe gingival and oral mucosal erosions; washing of the muzzle in water; stiff, short-strided gait; and synchronous diaphragmatic flutter. One group 2 horse that died had microscopic histopathologic features compatible with blister beetle intoxication. Apparently, the only clinical measurement that might differentiate blister beetle disease from other acute abdominal crises including monensin toxicosis, beside finding the beetles in digesta and contaminated hay, was the profound and stable hypocalcemia and hypomagnesemia. In terms of prognosis, only a continuum of tachycardia , tachypena and increasing creatine kinase activity were associated with nonsurviving horses.