Ivermectin Sensitivity & MDR1 Gene Test for Border Collies

The Border Collie is well-known throughout the United States as one of the smartest and most energetic working dog breeds. These agile, highly trainable dogs remain popular across many regions for herding livestock and excelling in competitive canine sports.

More than just working dogs, Border Collie puppies can be wonderful companions for active families, provided they receive plenty of mental challenges and vigorous exercise. Responsible care means committing time daily to walks and engaging activities that keep these lively dogs both stimulated and healthy.

Although generally durable and robust, Border Collies can inherit specific genetic issues that impact their wellness over time and necessitate careful management.

A key hereditary concern in dogs is sensitivity to ivermectin, caused by a mutation in the MDR1 gene (also called ABCB1). Dogs carrying this mutation are highly susceptible to adverse reactions from certain common veterinary medications, including some dewormers and allergy treatments.

When affected dogs are given these drugs, their bodies cannot efficiently process the medication, potentially resulting in serious neurological toxicity. Symptoms can include seizures, paralysis, and in worst cases, death.

Since this sensitivity is not visible externally, DNA testing plays a crucial role. It can classify a dog as clear, a carrier, or affected by the MDR1 mutation, helping owners and veterinarians avoid harmful drugs and choose safer options.

For breeders, MDR1 genetic screening supports ethical breeding by preventing the pairing of two carriers or affected dogs. This reduces the number of sensitive pups born and improves the breed's overall health and longevity.

What is ivermectin sensitivity or the MDR1 gene defect?

Ivermectin is a commonly used antiparasitic drug effective against a variety of worms and parasites. However, dogs with the MDR1 mutation are sensitive not only to ivermectin but also to several related medications containing macrocyclic lactones.

This mutation impairs the function of P-glycoprotein, a transporter protein responsible for pumping these drugs out of the brain. When P-glycoprotein is defective, these substances accumulate in the central nervous system, triggering harmful neurological side effects.

Signs of sensitivity include tremors, seizures, confusion, excessive drooling, and in extreme cases, coma. Quick diagnosis and intervention are vital to prevent fatal consequences.

The good news is that alternative medications are available for most conditions that typically require ivermectin-like drugs, allowing safe treatment once the dog's genetic status is known.

How is ivermectin sensitivity or the MDR1 gene defect inherited?

The MDR1 mutation follows an autosomal recessive inheritance pattern. Dogs fall into three categories:

• Clear: no mutation, no sensitivity risk.
• Carrier: one copy of the mutation, usually unaffected but can pass it to offspring.
• Affected: two copies of the mutation, showing sensitivity.

Knowing the genetic makeup of both parents helps predict the chances puppies will inherit sensitivity:

• Two affected parents will produce litters where every puppy has sensitivity.
• Two clear parents produce litters free of the mutation.
• Two carriers have a 25% chance that puppies will be affected, 50% that they will be carriers, and 25% clear.
• Combinations of affected, carrier, and clear parents result in predictable mixes.

DNA testing for ivermectin sensitivity in Border Collies

To determine your Border Collie's MDR1 status, a veterinario can collect a simple blood sample or cheek swab. The sample is sent to a certified laboratory that tests for the 4-base pair deletion mutation responsible for sensitivity.

The results indicate whether your dog is clear, a carrier, or affected. This information is instrumental for veterinarians to avoid prescribing harmful drugs and for breeders to make informed mating decisions.

While the MDR1 mutation is common in breeds like the Collie and Australian Shepherd, it is much less frequent in Border Collies in the US. Testing is still recommended when there is suspected mixed heritage or family history of sensitivity.

Responsible breeding and care

Utilizing DNA testing helps breeders reduce the incidence of the MDR1 mutation by avoiding mating two carriers or affected dogs. This approach greatly minimizes the risk of producing puppies sensitive to ivermectin.

Owners of Border Collies identified as sensitive should always inform their veterinarians and avoid treatments containing ivermectin or related drugs, instead opting for safer alternatives.

Understanding and managing this genetic condition helps protect the health of Border Collies, ensuring they lead active, fulfilling lives as working dogs or beloved family pets.

FAQs about the MDR1 gene defect and Border Collies

Can I tell if my Border Collie has ivermectin sensitivity without a test?

Short answer: No, sensitivity cannot be identified just by appearance; a DNA test is essential.

Signs of sensitivity only appear after exposure to certain medications, and the mutation cannot be diagnosed visually. Genetic testing is the only reliable way to determine a dog's MDR1 status.

Is the MDR1 mutation exclusive to Border Collies?

Short answer: No, the mutation also occurs in related herding breeds such as Australian Shepherds and Shetland Sheepdogs.

The mutation is found in several herding breeds sharing common ancestry. Testing is advised for these breeds in the US as a precaution against adverse drug reactions.

What happens if a dog with the MDR1 mutation takes ivermectin?

Short answer: The dog can suffer severe neurological symptoms, including seizures and possibly death.

The defective P-glycoprotein fails to protect the brain from the drug, causing toxic accumulation and symptoms like tremors, loss of coordination, and seizures, requiring emergency veterinary care.

Early testing helps prevent exposure and keeps affected dogs safe.

Where can I get my Border Collie tested?

Short answer: Many veterinary clinics across the US offer MDR1 genetic testing via blood sample or cheek swab.

Talk to your veterinario about requesting the MDR1 test. It is widely available through veterinary genetics labs such as UC Davis Veterinary Genetics Laboratory and Washington State University PRiME. Results usually return within weeks to guide safer medication and breeding decisions.

Conclusion

Awareness of ivermectin sensitivity and the MDR1 gene mutation is crucial for safeguarding Border Collies in the US. Genetic testing empowers owners and breeders to prevent dangerous drug reactions and make responsible decisions in partnership with their veterinarians.

By promoting informed breeding practices and vigilant care, we help ensure these remarkable dogs continue thriving as cherished family pets and hardworking partners nationwide.