Detection of levamisole and ivermectin in organ samples from a perished Collie

A collie, known for its breed-dependent adverse reaction to ivermectin, was without any clinical signs. The dog was prophylactically treated with 3 mg /kg KG (s.c.) of levamisole. Within 15 minutes, the dog showed convulsions, vomitus, and dyspnoe, and perished 2.5 hours after injection of the drugs. The pathological findings were not informative as to the cause of death, a nd with regard to the adverse reactions, additional application of ivermect in was not excluded. Therefore, organ samples were submitted for toxicologi cal analysis of both levamisole and ivermectin. For detection of levamisole and ivermectin, modified GC/MS and HPLC procedures were developed. Concent rations up to 535 mug levamisole and up to 26 ng ivermectin were found per g tissue. Both analytical methods are sensitive enough to detect these drug s after application of low doses. This study elucidates that combination of low-dosed ivermectin and levamiso le is no recommendable means against adverse effects of ivermectin, with re spect to collies. Moreover, the synergistic effects of ivermectin and levam isole suggests the same drug incompatibility in other dog breeds and animal species.