Australian Shepard MDR1 DNA TEST

Test Highlights:

  • DNA samples can be collected easily at home using buccal (cheek) swabs.
  • Dogs can be DNA tested at ANY age using the buccal swabs.
  • DNA results are emailed within 5 business days of receipt of the samples
  • Test fee is $58 (US) per canine, multi-test discounts may apply

Multidrug Resistance 1 (MDR1)

Multidrug Resistance 1 is inherited as an autosomal incomplete dominant disease. Dogs only need to inherit one copy of the MDR1 mutation to be at risk for sensitivity of certain drugs. Dogs with 2 copies of MDR1 can have more severe reactions.

The DNA test is an accurate, convenient, and affordable tool to help breeders avoid producing MDR1 carrier and affected offspring and significantly reduce the gene frequency in future generations.

There are 3 possible genotypes reported for Multidrug Resistance 1:

  • CLEAR (those having 2 copies of the normal allele and appear to be normal, not affected by MDR1)
  • CARRIER (those having 1 copy of the normal allele and 1 copy of the mutation, increased risk of drug sensitivity)
  • AFFECTED (those having 2 copies of the mutation and at risk for adverse drug reactions).

P-glycoprotein is a pump that removes certain drugs and toxins from the body.  A mutation in the ABCB1 gene associated with MDR1 prohibits P-glycoprotein’s ability to limit absorption, distribution, and excretion of drugs.  Dogs with one copy of the MDR1 mutation can have some drug sensitivity.  Dogs with two copies of this mutation can experience more serious neurologic symptoms like excess salivation, tremors, anorexia, blindness and possibly death.  The following is a list of drugs known to cause reactions:

Acepromazine (tranquilizer), butorphanol (pain control), doramectin, doxorubicin, emodepside, erythromycin, ivermectin (found in heartworm medications), loperamide (anti-diarrheal agent), milbemycin, moxidectin, paclitaxel, rifampin, selamectin, vinblastine (anti-cancer agent), vincristine and vinorelbine


*You should inform your veterinarian if your dog is a MDR1-carrier or MDR1-affected so they can give your dog the adjusted dosage or an alternative medication.  Other medications not listed may also cause a reaction.


Breeds, crosses and mixes of breeds that are more commonly affected by MDR1 are:  Australian Shepherd, Border Collie, Collie, English Shepherd, German Shepherd Dog, Longhaired Whippet, McNab Shepherd, Miniature Australian Shepherd, Old English Sheepdog, Shetland Sheepdog, Shiloh Shepherd, Wäller, White Shepherd Dog


Canine DNA frequently asked questions


For more information about how these test results can be used for registration, contact the Orthopedic Foundation for Animals (OFA).