Why test your dog for the MDR1 gene defect

The multidrug resistance mutation 1 (MDR1) refers to the mutation that occurs at the ABCB1 gene or MDR1 gene, which makes the animal more sensitive to the effects of certain drugs.

The MDR1 gene defect impairs your dog’s ability to accept important medications that protect them against illnesses as well as parasites. If your dog does have this gene defect, they can react to medicine adversely and, depending on the severity of the defect, even fatally.

For dogs that possess the gene mutation, higher levels of drugs enter their brain which increases the effects of common drugs such as the following:


  • Ivermectin, milbemycin, selamectin (parasite treatment)
  • Loperamide (anti-diarrhoea)
  • Acepromazine (tranquiliser)
  • Butorphanol (pain relief)
  • Doramectin, doxurubicin, emodepside, erythromycin (heartworm treatment)

A dog that possesses the MDR1 gene mutation will require very careful considerations when it comes to medications and dosages. Aside from this, determining if your dog possesses the mutation will also help you make an informed decision about breeding.

How common is the MDR1 gene mutation among dogs?

Although it can occur with any dog, the MDR1 mutation is most commonly observed among purebred herding dog breeds. Mixed breed dogs carry a 35% risk of carrying the gene defect, while purebred dogs carry a much higher 75% risk.

For the MDR1 Test, these are the breeds that can be tested:


  • Aussiedoodle
  • Australian Cobber Dog
  • Australian Shepherd
  • Border Collie
  • Collie
  • Czech Wolfdog
  • Czech Vlcak
  • English Shepherd
  • German Shepherd Dog
  • Longhaired Whippet
  • McNab Shepherd
  • Miniature Australian Shepherd
  • Old English Sheepdog
  • Shetland Sheepdog
  • Shiloh Shepherd
  • Smooth Collie
  • Waller
  • White Shepherd
  • White Swiss Shepherd

Dogs inherit one copy of the MDR1 gene from each parent. If your dog happens to have inherited a defective copy of the gene from a parent, it puts them at risk of suffering the potentially life-threatening effects of the defect.

If your dog happens to have two defective copies of the gene, they may suffer even more severe side effects such as tremors, blindness, anorexia, excess salivation, and death.

Does your pet have the defect or not? The best way to determine this is to take a Dog Multidrug Resistance 1 (MDR1) Test.

Cost of the MDR1 test

The Dog MDR1 test is being offered at only €79 for a sample of one dog. There is an option to order more tests for an additional cost.

How the MDR1 test is carried out

Take away the guesswork with the EasyDNA MDR1 Test. It is a fast and reliable way to determine whether your dog possesses the MDR1 gene defect or not. This way, you can work with your veterinarian to address your pet’s specific medical needs.

The process of our MDR1 test is very straightforward. Upon ordering your test, we will send you a sample collection kit that allows you to collect your dog’s cheek swab samples. Using our kit, there is no need to draw blood or go to the veterinarian for sample collection.

Once you are able to collect your dog’s DNA sample following the instructions provided in the kit, all you need to do is send it back to our laboratory for testing.

Your test results

After our laboratory receives your dog’s sample, you can expect to receive your test results via email in 7 working days from receipt of samples at the laboratory. You will receive one of three possible outcomes:


  1. CLEAR result: Your dog has inherited 2 good genes that are free from defects or mutations.
  2. CARRIER result: Your dog has inherited 1 normal copy of the gene and 1 mutated copy. This means that the animal may have an increased risk of suffering the effects of MDR1 gene mutation.
  3. AFFECTED result: Your dog has inherited 2 copies of the mutated MDR1 and is at risk of suffering adverse or life-threatening reactions to medications.


EasyDNA uses the latest in DNA testing technology, assuring you that the results of your MDR1 test are highly accurate and reliable. If you need more information regarding this test, please contact our Customer Service or email us directly.

Other Dog Disease Genetic Tests from EasyDNA

At EasyDNA we offer a range inherited disease screening tests such as the MDR1 including the following:


We also offer a comprehensive genetic screening test covering 175+ diseases and traits through our DogCheck Genetic Screening Test. This is one of the most comprehensive tests on the market ideal to manage the health of your dog and for breeders.

Other Dog DNA Tests from EasyDNA

We also offer a wide range of other types of dog DNA tests looking at different personal aspects of your dog such as the  Premium Dog Testing Package, an all-in-one testing package that includes our Dog Allergy Test, Dog Breed Test, and Dog Genetic Age Test.

Find out more about your dog and start your journey to a healthier pet!

DogCheck (Canine) Genetic Disease Test
Dog von Willebrand Disease Test
Dog Progressive Retinal Atrophy, Progressive Rod-Cone Degeneration (PRA-prcd) Test

We use cookies to offer you a better browsing experience, analyze site traffic, personalize content, and serve targeted advertisements. Read about how we use cookies and how you can control them by clicking "Cookie Settings." If you continue to use this site, you consent to our use of cookies.