MDR1 Multi Drug Resistance – Dog

Multi Drug Resistance 1 or Multidrug Sensitivity seems to inherited in an autosomal dominant way with incomplete penetrance. Affected dogs are susceptible to neurotoxicity following the administration of certain commonly used drugs like Ivermectin. The condition is linked to the ATP Binding Cassette Subfamily B Member 1 (ABCB1) gene, also known as the multidrug resistance (MDR1) gene. This gene encodes for a drug transporter protein called P-glycoprotein (P-gp), which plays a crucial role in the blood-brain barrier by preventing certain drugs from accumulating in the brain. Dogs with two copies of the MDR1 variant are at higher risk and should be closely monitored to avoid adverse reactions to certain medications. Some dogs with one copy of the MDR1 variant have also been reported to exhibit multidrug sensitivity, though symptoms vary hugely.

Neurotoxicity following drug administration, which varies according to dose, is the main sign. Dogs may show ataxia, tremors, seizures, excessive salivation, obtundation, bradycardia, mydriasis, loss of menace, loss of papillary light responses, coma and respiratory arrest.

This test is based on an association study.

The disorder is noted as incomplete dominant. It means that, in some cases, carriers of the mutation have been observed to present with a milder form of the disorder and in other cases no symptoms were present at all.

Pubmed ID: 11692082

Year published: 2001

Omia ID: 1402

Omia variant ID: