Acute toxicity of aflatoxin B1 and rubratoxin B in dogs.

The effect of ip administrated aflatoxin B1 and rubratoxin B, singly and in combination, on dogs was determined by serum tests, by observations of clinical signs and survival times, and by evaluation of gross and microscopic lesions. The dog is sensitive to the toxic effects of both mycotoxins. Glutamic-oxaloacetic transaminase, lactic dehydrogenase and alkaline phosphatase activities and survival time varied in relation to dose and to the mycotoxin(s) administered. All three plasma enzymes were elevated regardless of dose with the combination of aflatoxin B1/rubratoxin B at 24 hr after dosing, except LDH, which was within the normal range but only at the lowest dose level. Several serum constituents including BUN, cholesterol, uric acid, and total bilirubin were elevated, whereas serum glucose was depressed in dogs treated with the multiple-toxin regimen; these changes were not seen in dogs given only aflatoxin B1 but were characteristic in rubratoxin-treated animals. In general, gross findings at necropsy were similar in all dogs regardless of the dose regimen. A striking similarity existed in the histologic changes observed between lesions experimentally induced by the mycotoxin combination and those lesions reported for dogs fed toxic feed in laboratory studies or in natural cases of hepatitis X. Of particular similarity were the severe kidney lesions observed in dogs exposed to the mycotoxin combination and kidney lesions reported in natural outbreaks of hepatitis X. There can be little doubt of an association between hepatitis X and aflatoxin B1, although it is apparent that the disease probably involves more than a single toxic factor. Our results suggest that hepatitis X in dogs includes aflatoxin B1 as a primary etiological factor but that rubratoxin B also may be involved.