The short answer
The MDR1 gene affects how a dog's body handles certain common medications. Dogs with a variant can react badly to some drugs at normal doses. It's most common in herding breeds and their mixes. Even Wisdom Panel's entry test (Breed Discovery) includes MDR1. If your dog has the variant, tell your vet before any treatment.
Who should check
- Herding breeds such as collies, shepherds and their mixes.
- Mixed breeds of unknown ancestry.
- Any dog before planned treatment, if you're unsure.
Tests that include MDR1
Wisdom Panel Breed Discovery includes the MDR1 test; full-panel tests such as Wisdom Panel Premium and Embark Breed + Health cover broader health screening.
Using the result
- Add it to your dog's vet record.
- Mention it before any medication, including parasite treatments.
- Your vet can confirm with their own test.
SafetyNever change or skip prescribed medication based on a DNA result without your vet.
Products mentioned
Questions readers ask
What does MDR1 mean on a DNA test?
It flags a gene variant affecting how some drugs are handled.
Which dogs carry MDR1 variants?
Most often herding breeds and their mixes.