MDR1 Drug Sensitivity

MDR1 often presents in young adulthood, only because this is most commonly when a dog is first exposed to a problem drug like high dose ivermectin or acepromazine.

Symptoms arise after a dog has received an MDR1 problem drug or dosage, and can range from vomiting and diarrhea to lethargy, seizures, or coma.

This is usually a retroactive diagnosis after a dog has an adverse reaction to a problem drug--however, genetic testing could help you avoid a first reaction altogether.

MDR1 is perfectly avoidable simply by avoiding the problem drugs, or problem dosages.

Talk to your vet about your dog’s MDR1 result and share Washington State University’s list of potential problem drugs.

Monitor your dog in areas with horses or livestock, as ivermectin and similar problem drugs are often stored or used in these locations.

Prevent your dog from eating livestock feces, which can contain harmful levels of certain problem drugs.

The Multidrug Resistance, ABCB1 mutation, is particularly common in herding breeds including Australian Shepherds, Collies, and Border Collies, though many other dog breeds are affected. The veterinary adage, "White feet don't treat!" draws from the fact that many high risk breeds often have white markings on their feet; however, we know now that MDR1 is common in many dog breeds and mixes, many of whom do NOT have white feet!

Gene

ABCB1

Inheritance type

codominant

Clinical category

Clinical

Citations

1. Mealey et al 2001
2. Han et al 2010
3. Neff et al 2004
4. Barbet et al 2009
5. Gramer et al 2011

• Australian Cattle Dog
• Australian Shepherd
• Border Collie
• Chinook
• Collie
• Collie (Scottish-Type)
• Czechoslovakian Vlcak
• Danish-Swedish Farmdog
• English Shepherd
• German Shepherd Dog
• Australian Kelpie
• Koolie
• Windsprite
• McNab
• Miniature/MAS-type Australian Shepherd
• Old English Sheepdog
• Saarloos Wolfdog
• Sheepadoodle
• Shetland Sheepdog
• Shiloh Shepherd
• Silken Windhound
• Stumpy Tail Cattle Dog
• Whippet
• White Shepherd