Dog Genetic Tests: Why You Should Test For the MDR1 Mutation

Like the Embark Breed & Health Kit and the Wisdom Panel DNA Test, dog genetic tests analyze your dog's DNA to determine if they carry any genetic mutations associated with common canine health issues.

These tests are straightforward to take for you and your dog(s). Further, the price has come down considerably, usually only costing around $100, give or take $20. 

In many cases, if you know in advance that your dog carries one or more of these genetic mutations, you can prevent serious problems completely and alleviate the health problems as they express themselves over your dog’s lifetime.

How to Get Started

Dog saliva sample tube for DNa
  1. 1
    Order the Test Kit: To get the dog genetic testing started, you simply order the kit online, and they send it to you in the mail. 
  2. 2
    Take Your Sample: Inside the kit, specific instructions tell you how to swab your dog’s inner cheek to collect a DNA sample so that you will not contaminate the sample. 
  3. 3
    Get it Together: You then place the samples (they usually ask for two) in the tubes provided with a particular solution to preserve the DNA and ensure it does not degrade before they have a chance to analyze it. 
  4. 4
    Create Your Account: Your dog's sample is specially coded, and you use this code to register the kit online and create an account.   
  5. 5
    Mail it Back: You then send the sample back to the company in the envelope provided. 
  6. 6
    Wait For Results: The results are reported to you in your online account about two weeks later. 

Below, you will find detailed information about the MDR1 mutation that affects a significant percentage of dogs’ health. However, keep in mind that these genetic tests look for many mutations at once.

The full report you get when you order a canine genetic test will cover well over one-hundred mutations.

MDR1 Mutation (MDR-1 Mutation)

DNA Mutation

If it turns out your dog has the MDR-1 mutation, knowing this can save his or her life! MDR is an acronym that stands for "multidrug resistance gene." 

Dogs that carry the MDR1 mutation are genetically predisposed to having very bad reactions to multiple drugs that veterinarians commonly administer.

With the MDR1 mutation, dogs may not flush out a drug quickly because this gene codes for a P-glycoprotein protein that helps flush out toxins in the dog's body. 

Specifically, it keeps these toxins from building up in the brain. The MDR1 mutation either blocks the production of this protein or causes it to be deformed to the point it doesn't function properly. 

Without P-glycoprotein to flush out the drugs, more of the drug will be absorbed than is typical or expected at a particular dosage. If these drugs build up in a dog's brain to toxic levels, they can cause significant neurological damage. 

Common Symptoms Include: 

  • Tremors
  • Disorientation
  • Seizures
  • Ataxia (loss of control over bodily functions)

The unintended buildup of these drugs can result in blindness and even death!

What drugs are dangerous if your dog has the MDRI mutation?

Dangerous Drugs Include:

Anti-parasitic Drugs: ivermectin, milbemycin, moxidectin, and selamectin

Anti-diarrheal Drugs: loperamide (also known as Imodium)

Anti-cancer Drugs: doxorubicin, vinblastine, and vincristine

Antibiotics: erythromycin and rifampin

Tranquilizer Drugs: acepromazine

Pain Medications: butorphanol

Immunosuppressive Drugs: cyclosporin

Heart Drugs: digoxin

Other drugs that may cause issues in the presence of the MDR1 mutation include:

  • Domperidone
  • Etoposide
  • Mitoxantrone
  • Morphine
  • Ondansetron
  • Paclitaxel
  • Quinidine
  • Rifampicin

Talk to Your Veterinarian  

Keep in mind that new drugs are being developed and tested all the time. If you determine with a dog genetic test that your dog has an MDR1 mutation, be sure to ALWAYS remind your veterinarian of this fact before she administers ANY type of drug. 

You may also want to stress your concern, so they are looking into the possibility of this reaction with similar medications. In fact, you may want to do so before each visit because veterinarians often start administering a drug without you even know it is happening! 

Talk to Your Surgeon 

Family consulting with surgeon before surgery

Likewise, if you give your consent for any type of surgery, even relatively minor surgery, be sure the surgeon knows your dog has this mutation. You understand that the surgeon may differ from your regular veterinarian, perhaps another partner in the same veterinarian clinic.

Most mutations occur on genes that are either dominant or recessive. If a gene mutation is dominant, a dog will only need one copy of that mutation, from only one parent, to fully express that trait. On the other hand, if a gene mutation is recessive, then two copies of the mutation, one from each parent, are required to express that trait. 

However, the MDR1 mutation is unusual in that it is what's called "incompletely dominant." This means that if a dog has one copy of the MDR1 mutation, it will be partially expressed. If, on the other hand, a dog has two copies of the MDR1 mutations, it will be fully expressed.

From a practical perspective, if your dog has just one copy of the MDR1 mutation, you should still be very careful and ask your veterinarian not to use certain drugs. Even with partial expression, the P-glycoproteins produced may be damaged to the point that certain drugs can cause significant problems, especially if administered medium to heavy dosages. 

In Review

It's rarely worth the risk to knowingly use certain drugs on a dog with a single copy of the MDR1 mutation. Furthermore, if your dog has two copies of this mutation, it will be even more dangerous for your dog to receive certain drugs. Even a small amount of certain medications could kill your dog. 

Either way, you should insist that alternative drugs be used that do not negatively affect dogs with the MDR1 mutation. You should know too that alternative drugs have been developed because this mutation is so common.

While the MDR1 mutation is not found in most dogs, it is found in a significant number of them. For example, Wisdom Panel reports that seventy percent of all collies (except border collies) and fifty percent of Australian Shepherds have this mutation! It's also found in ten percent of all German Shepherds and fifteen percent of all Shetland Sheepdogs

Perhaps the most crucial information you can have if you have adopted a mixed breed dog is that five percent of all mixed-breed dogs carry the MDR1 mutation! This means that five mixed-breed dogs out of every one-hundred of them will carry at least one copy of this mutation.

Final Thoughts

The MDR1 mutation is only one of more than one-hundred fifty health-related mutations that dog genetic tests already analyze for and report. Two of the most popular consumer-end canine genetic tests include Embark Breed & Health Kit and the Wisdom Panel DNA Test

It is very likely that these tests, or modified versions, will screen for even more genetic mutations in the near future so stay tuned!

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