ABCB1 and Tremor: For example, Bissonnette et al. [94] described a MDR1(+/-) juvenile mixed breed dog which showed neurological toxicity including ataxia, tremor and depression after daily ivermectin application at 670 μg/kg after seven weeks of therapy, indicating that at least one intact MDR1 allele may protect the dog from acute neurotoxicity after high dose applications of ivermectin.