MDR1 - Ivermectin Sensitivity
 
Overview

MDR1 is a hypersensitivity to the drug Ivermectin (and an array of other drugs.)

It is NOT a genetic disease, and dogs that carry this gene mutation are perfectly healthy, it is, in simple terms, an allergy to certain types of drugs.

In affected dogs the drug and other toxins cannot be removed from the brain and surrounding tissue, resulting in the accumulation of toxins and can lead to adverse neurological affects.

Ivermectin is a commonly used heartworm prevention drug; a mutation in the MDR1 gene in dogs prevents the production of a transport protein, which removes the drug and toxins from the brain and tissues. The resulting accumulation from this failure to detoxify the brain and tissues often results in severe neurological affects such as hyper-salivation, ataxia, blindness, coma, respiratory arrest and death.

Unfortunately this sensitivity is not only restricted to Ivermectin, but many preventative canine drugs, it is essential that owners be aware if their dog is MDR1 sensitive as many affected dogs require as little as 1/200th of the dose to cause fatal toxicity in unaffected dogs.

Severity – 5

MDR1 has an extreme degree of severity as it can cause immediate death, particularly if the owner/vet is unaware that the dog is affected.

Symptoms

A dog sensitive to Ivermectin will show no signs until given the drug, something as routine as a 6-month heartworm injection has be linked to the accidental and immediate death of numerous dogs.

It is important that testing for this sensitivity is carried out early, as although a dog may show no adverse reaction to the administration of drugs, they may still produce affected offspring if they themselves are carriers of the mutation.

Genetic Testing

Genetic Technologies provides a DNA test that determines the genetic predisposition to MDR1. This is the company Eishund uses to DNA profile & test all of our dogs.

How is MDR1 inherited?

The MDR1 gene defect is inherited as an autosomal recessive condition.
An abnormal gene on one of the autosomal chromosomes from each parent is required to cause the condition. Dogs with only one abnormal gene in the gene pair are called carriers, but since the gene is recessive they do not exhibit the condition.

Affected dogs are homozygous for the condition and can only receive a defective MDR1 gene from each of its parents.

Breeding Recommendations

Any dog carrying a mutant gene should be mated to a normal/normal (clear) dog. This will ensure that NO affected puppies are produced in the litter.

When one parent carries a mutant gene, (Both Inga & Thor are carriers) we have decided that we will test all puppies in the litter prior to their new homes to identify any carriers. We have an ethical obligation to ensure we are open & honest with ALL information pertaining to our puppies, even though carrier puppies are just as 100% healthy as their clear litter mates & will NEVER have any MDR1 sensitivity issues. So you can be assured that Eishund & our sister Kennel Fanuilos, will never ever produce an MDR1 affected puppy. :)

At no stage EVER will Eishund breed with an untested dog, affected dog, or do carrier x carrier matings.

MDR1 Breeding Pair Combinations and Outcomes

• Sire (father) MDR1 Result
• Dam (mother) MDR1 Result
• Litter (progeny) MDR1 Result