MDR1 gene defect in dogs – what is it?

A question that many new dog owners ask is “What is the MDR1 genetic defect?”

The first time you encounter the term MDR1 genetic defect is when you buy or adopt a dog. This topic affects you as a dog owner or future dog owner as well as breeders, veterinarians and agents.

Reputable breeders and animal shelters inform potential owners about this, as this genetic defect is common in certain breeds of dogs. It is crucial to understand this genetic defect as it can pose great dangers to affected animals.

The danger here comes particularly from certain medications. What is an ordinary tablet for other dogs can cause serious health problems or, in the worst case, death for a dog with the MDR1 gene defect.

That's why it's important for you as a dog owner to not only understand this defect, but also what you should pay attention to and how to deal with a confirmed MDR1 genetic defect. We at GenoLine address the topic in this article.

MDR1 gene defect: definition and symptoms

The MDR1 gene defect is a genetic, i.e. hereditary, disorder that can occur in both dogs and humans. The MDR gene, which is affected in this disorder, is responsible for producing a protein called P-glycoprotein.

In dogs with the MDR1 gene defect, this protein is largely or completely missing. P-glycoprotein has a crucial function in the body: it normally limits the absorption of harmful foreign substances such as drugs and poisons into the brain and intestines.

It also helps to quickly transport these harmful substances to the liver and kidneys in order to neutralize and eliminate them. In this way, the gene is intended to prevent poisoning and protect the organism.

As a result, without this defense mechanism, drugs and other harmful substances can more easily penetrate the brain and other organs and become dangerous for dogs with the MDR1 genetic defect. These dogs are prone to toxic reactions to medications such as Ivermectin, Loperamide and many others.

The symptoms of an MDR1 gene defect in your dog

In dogs, the symptoms of an MDR1 gene defect can be varied and frightening. This genetic defect requires special attention in order to be recognized in time and to be able to take action if symptoms appear.

A common sign of the MDR1 gene defect in dogs is vomiting. Your dog may vomit suddenly and repeatedly for no apparent reason. Diarrhea may also occur, which can often be severe and persistent.

Dogs with this genetic defect may also suffer from ataxia, which is a coordination disorder. They may walk unsteadily, stumble or even fall.

Depression and generally lethargic behavior are other possible signs. What can also occur in particularly severe cases are seizures or even a coma.

You're probably already familiar with these symptoms from poison warnings. Since a dog with the MDR1 gene defect lacks the protective protein, this is exactly what happens if your dog shows these symptoms.

That's why it's crucial to act quickly and see a vet immediately as soon as you notice any of these signs in your dog.

How can the MDR1 gene defect be precisely determined?

Determining a possible MDR1 genetic defect is not only of great importance for the safety of your four-legged friend, but is now also very precise and efficient.

Since this defect has been found particularly frequently in certain breeds, it is advisable, especially when adopting one of their members, to test the dog for the MDR1 genetic defect.
The dog breeds in which the MDR1 gene defect has been observed particularly frequently include:

• German Shepherds
• white German Shepherds
• Australian Shepherds
• (Border) Collies
• Shetland Sheepdogs (Shelties)
• Old English Sheepdogs
• some Labradors
• some Irish Wolfhounds
• Mixed breed dogs from the breeds mentioned above

This genetic defect in your dog is usually detected by veterinarians. You take a blood sample from non-coagulable EDTA blood and send it to a specialized laboratory.

Another way to identify the MDR1 gene defect in your dog is our DNA dog breed determination test . This test can not only determine your dog's breed or breeds, but also determine the presence of the MDR1 genetic defect.

Tip: At GenoLine you will also find allergy tests for dogs or other tests that you can use to carry out a health check on your dog .

Cause of the MDR1 gene defect in your dog

The cause of the MDR1 gene defect in your dog is due to a genetic mutation of the MDR1 gene. This gene mutation significantly affects how the gene works.

The MDR1 gene defect can be inherited in two different ways. In the case of homozygous inheritance, both parents had the genetic defect, which means that your dog inherited two defective copies of the gene. As a result, symptoms tend to be more severe.

With heterozygous inheritance, only one parent had the genetic defect and the symptoms are milder because your dog has an intact copy of the gene.

Can the MDR1 gene defect be treated or treated?

The MDR1 gene defect is, as you now know, a genetic abnormality. That's why it accompanies dogs throughout their lives that have inherited this MDR1 genetic defect and there is no possibility of cure.

However, this hereditary defect can be treated in relation to your dog's symptoms and quality of life. It's important to understand how you can protect your four-legged friend from the potential dangers of this genetic defect.

Dogs with the MDR1 gene defect are particularly susceptible to certain medications that are safe for other dogs. These include antiparasitics such as ivermectin and doramectin, emodepside (in case of overdose and non-fasting use), as well as cytostatics such as vincristine, vinblastine and doxorubicin. Other medications such as ondansetron, erythromycin, digoxin and loperamide also prove to be harmful.

To protect your dog's well-being, he should never take medication without medical advice. Your veterinarian will be able to prescribe alternative medications or determine appropriate dosages to ensure your dog does not experience harmful side effects.