The MDR1 (ABCB1) mutation causes life-threatening drug toxicity in affected dogs when given commonly used medications, making genetic testing a critical safety and welfare intervention for predisposed breeds.
MDR1 toxicity is a preventable welfare catastrophe - dogs given seemingly routine medications experience severe neurological toxicity and potentially die because their breed-associated genetic variant was not identified in advance. The experience of drug toxicity is acutely terrifying: tremors, blindness, and neurological collapse affecting a dog that was normal hours before. The simple genetic test that prevents this is among the highest-value welfare investments available for predisposed breed owners. Once identified, affected dogs live completely normal lives with appropriate medication selection.