Multidrug Resistance

Multidrug Resistance 1 (MDR1), or Invermectin Sensitivity, causes reactions to certain classes of drug. An inability to metabolize these drugs can cause severe reactions or death even at low doses, and so vets should be made aware of this disorder.

An autosomal recessive condition caused by a mutation in the ABCB1 gene.

Mealey KL, Bentjen SA, Gay JM, Cantor GH. Ivermectin sensitivity in collies is associated with a deletion mutation of the mdr1 gene. Pharmacogenetics. 2001 Nov;11(8):727-33