Why are many Border collies sensitive to Ivermectin?

The Border collie is a working herding dog breed that is also the world’s most intelligent breed overall, and Border collies are still used as farm dogs within working roles all over the UK and further afield. Border collies are also great at all types of canine sports, including flyball, agility and obedience, and they’re very versatile and able to learn a wide range of different commands and execute a vast number of skills when trained to do so.

They also make for popular pets, although many first-time Border collie owners significantly underestimate the amount of exercise that dogs of the breed require. Border collies are energetic and really smart dogs that are unmatched in terms of their potential abilities, and that are a great choice of pets for people who want a highly intelligent dog that can do a lot of different things.

However, if you are thinking of buying or adopting a Border collie, there is one thing about the breed that you should know – a significant amount of Border collies (around three quarters of all dogs of the breed, by some estimates) are sensitive to a specific antiparasitic agent called Ivermectin, which is commonly used as a wormer in a wide variety of different animals including dogs.

Ivermectin sensitivity can cause an acute and dangerous adverse reaction in dogs that are intolerant of it, and Ivermectin should never be used as a wormer for Border collies for this specific reason. This is something that your vet will already know, and may have explained to you when choosing the right wormer for your dog – but if you are wondering why Border collies are sensitive to Ivermectin and if there is any way to find out whether or not your dog is one of them, this article is for you.

Read on to find out why many Border collies suffer from Ivermectin sensitivity, and what this means for them.

More about Ivermectin

Ivermectin is a type of anthelmintic or antiparasitic agent that is used in many animals (including livestock, horses, birds, small mammals and dogs) as a wormer. Ivermectin works as a wormer by affecting parasites on a cellular level, filling their cells with chloride, which is highly toxic in high enough doses and so, kills and eradicates worms from the body.

Ivermectin is safe for the animals that it is used to treat because the receptor cells in the animals that we use Ivermectin for don’t permit dangerous amounts of chloride through to bind with the body’s cells as they have different types of receptors, meaning that it kills parasites without harming the host animal.

However, dogs do have receptor cells in their brains that can bind with Ivermectin to cause the same type of toxic response achieved in parasites, but this does not occur in most dogs because there is a membrane in place protecting the brain itself, called the blood-brain barrier.

Why are many Border collies sensitive to Ivermectin?

Many Border collies possess a specific gene mutation (called MDR1) that results in a fault in the blood-brain barrier, which would otherwise stop the harmful agents within Ivermectin entering the brain and binding with the cells there to create toxicity.

Because a significant amount of Border collies possess this MDR1 gene mutation, Ivermectin can be very dangerous for them – and for dogs of mixed breeds with Border collie ancestry. Because many working farm dogs and other non-pedigree herding dogs have some Border collie ancestry too, Ivermectin is generally not used for any working herding dog types.

How serious is it if a Border collie has Ivermectin?

If your Border collie has the MDR1 gene mutation, they are apt to react badly to Ivermectin if this is given to them as a wormer, and it can make them quite sick. If a Border collie with Ivermectin sensitivity is given Ivermectin, they may display a range of symptoms, including:

• Problems getting up and down.
• Unsteadiness on their feet, potentially with shaking or trembling.
• Lethargy and sleepiness.
• Lack of response to stimulus.
• Hypersalivation and potentially, vomiting.
• An altered heart and respiratory rate, usually much slower than normal.
• In severe cases, affected dogs may fall into a coma, and/or suffer from seizures.

Ivermectin sensitivity in the Border collie can usually be treated if diagnosed quickly and managed appropriately, but treatment must be sought promptly and is not successful in every case if left too late.

What should you do if your Border collie has come into contact with Ivermectin?

Your vet will certainly know that most Border collies should not be given Ivermectin, and you should not give your dog any off-the-shelf worming product or something you have chosen or bought from elsewhere without your vet’s approval.

If your Border collie has been given Ivermectin, contact your vet immediately (even if your dog appears fine) as your vet will want to monitor them to ensure that there are no ill effects.

Can I find out if my Border collie is sensitive to Ivermectin?

If you keep your Border collie as a pet or working dog and don’t intend to breed from them, simply ensuring that they are not given Ivermectin should be sufficient to play it safe. It is best to assume your Border collie will be sensitive unless you know otherwise, as so many dogs of the breed are.

However, there is a DNA test for Ivermectin sensitivity in the Border collie that you might want to consider undertaking on breeding stock if you wish to breed from your Border collie, and you can find out more about it here.