There are many unseen genetic conditions that are not widely known. Multiple Drug resistance is one such condition. It is not often a consideration when giving your dog medication but if the condition is present, it can have some devastating effects. Knowing the genetic status of your canine companion can help you make decisions when it comes to your pup’s health.

What is MDR1?

Multiple Drug Resistance (MDR1) is a condition resulting from a mutation in the ABCB1 gene in canines. This mutation increases sensitivity to drug toxicity. The ABCB1 gene codes for the production of p-glycoprotein which helps to remove medication and other toxins from the body, most importantly from the brain. When these toxins and medications build up in the cerebrospinal fluid around the brain (and sometimes even crossing the blood brain barrier) the p-glycoprotein is supposed to remove the toxins. If they are not removed, it leads to adverse neurological symptoms and side effects.

The gene can be inherited from the pup’s parents. It is inherited in an autosomal incomplete dominant manner. This means that even if your dog only inherits one copy (from the two possible copies that can be inherited), they can still be at risk of developing drug toxicity.

If your dog does carry the mutation for MDR1, not all medications will be detrimental. The most common drug that has an effect is Ivermectin and other anti-parasitic medications. Other medications include chemotherapy drugs, tranquilisers such as Acepromazine, pre-aesthetic drugs such as Butorphanol, and over-the-counter antidiarrheal medication such as Loperamide.

What are the Symptoms?

Drug toxicity is not a thing you will see immediately. The symptoms will manifest slowly as the dog is exposed to more of the medications. Symptoms such as vomiting, weakness, and uncoordinated movement will get worse over time. If the medications continue to be administered, it can cause more severe symptoms such as seizures and blindness.

What are the treatment options?

Unfortunately, once the toxicity is there, there is not much that can be done except stopping the medication and treating the symptoms. The best course of action would be to genetically test your dog early in its life. This way you will know if they carry the gene mutation or not, allowing you and your vet to choose the appropriate medications for your dog.

MDR1 is something all pet owners should be watching out for in their canine companion. The mutation is present in various breeds. The name for this condition definitely belies the seriousness of the disease, but with genetic testing, it is something that can be avoided.

Where can I get genetic health tests done?

At ZooOmics we provide both health and colour testing as well as DNA profiles for both canine and feline. We utilise innovative technology for our mutation testing and provide you with certificates for all testing done, which can be submitted to registrars and breed societies.

Contact the Team at info@ZooOmics.co.za for any enquiries on sample collection, shipping of samples, sample processing, and services offered. Alternatively, visit their website at www.zooomics.co.za to download the sample submission form.