Severe combined immunodeficiency DNA testing for the Jack Russell dog breed

The Jack Russell is a popular small dog breed of the terrier type, which is one of the most common dog breeds that most of us see on a regular basis out and about in the UK. Jack Russells are the 11th most popular dog breed in the UK overall, and these plucky, entertaining and sometimes quite stubborn dogs have bags of personality and a lot of character.

Whist the Jack Russell might be on the small side, they are no toy dogs, and Jack Russells are often said to have huge personalities that belie their small size. They require active owners who can provide for the dog’s relatively high need for exercise, and that are competent and experienced at training and managing dogs, ideally dogs of the terrier type.

Jack Russells are very typical terrier dogs that tend to have a strong prey drive, be very bold, and often, like to dig and cause major mischief too! They can also be prone to dominance if improperly managed, and they will hold their own in the rough and tumble of the dog park with even much larger dogs.

The Jack Russell dog breed was originally developed for working roles (such as keeping rodent populations under control) and as such, they tend to be robust and hardy and not prone to being particularly fragile or delicate. However, there are a few hereditary health conditions that can be found within certain Jack Russell breed lines that can significantly shorten the lifespan of affected dogs, and reduce their quality of life as well.

However, many such health conditions can be predicted prior to breeding if dog breeders make use of some of the relevant DNA testing schemes that are in place for specific dog breeds, which are designed to identify the markers of the gene faults that cause certain health conditions to enable breeders to select healthy parent stock.

One Jack Russell health condition for which a DNA test is available is called severe combined immunodeficiency or SCID for short, and this causes affected dogs to be highly vulnerable to becoming acutely ill from what would otherwise be a minor ill or infection in a healthy dog. This tends to result in mortality at a very young age.

However, by DNA testing parent stock prior to breeding, Jack Russell breeders can identify this trait and ensure that it is not passed on to further generations, and that is what we will be talking about within this article. Read on to learn more about severe combined immunodeficiency in the Jack Russell, including how it is inherited and how to get a dog tested to find out their status.

What is severe combined immunodeficiency in the Jack Russell?

Severe combined immunodeficiency is a rare type of hereditary disorder that affects the dog’s immune system. This means that when the dog is exposed to infections or everyday viruses or bacteria that the immune system of healthy dogs fight off with ease, affected dogs are apt to become very sick very quickly, as their bodies do not produce the required immune response that is necessary to fight off the condition.

Generally, severe combined immunodeficiency proves fatal in affected dogs at a young age, often before the age of six months old.

This does of course mean that it is extremely unlikely that an affected Jack Russell will be used for breeding due to the condition’s mortality rate prior to the dog reaching adulthood, but dogs may also be carriers of the condition (and so, can pass on the gene fault for it to their young) without being affected by severe combined immunodeficiency themselves.

How might a Jack Russell inherit severe combined immunodeficiency?

Severe combined immunodeficiency in the Jack Russell is passed on from dog to dog by means of autosomal recessive heredity. This means that the effect of the genes inherited from both sides of a dog’s parentage (their dam and sire together) is what dictates the status of the litter that they have.

Dogs are assigned with a status of either clear, carrier or affected, and whilst carriers will themselves be healthy, depending on their mating match, they may pass the affected form of the condition on to their pups.

If you have two prospective parent dogs DNA tested for severe combined immunodeficiency to find out the status of both of them, you can predict the status of their future litter too, as follows:

• Breeding two Jack Russells with the affected form of severe combined immunodeficiency will result in a litter that is affected in its turn. However, this is an extremely unlikely situation due to the generally young age of death of affected dogs.
• Breeding two clear Jack Russells will result in a clear litter.
• Breeding two carrier Jack Russells will result in a litter within which each pup has a 50% chance of being a carrier, a 25% chance of being clear, and a 25% chance of being affected.
• Breeding a carrier with an affected dog will result in a litter within which each pup has a 50% chance of being a carrier and a 50% chance of being affected.
• Breeding a carrier with a clear dog will result in a litter within which each pup has a 50% chance of being a carrier and a 50% chance of being clear.
• Breeding a clear dog with an affected dog will result in a litter of carriers.

How can I get my Jack Russell DNA tested for severe combined immunodeficiency?

If you intend to get your Jack Russell DNA tested for severe combined immunodeficiency as the basis of making a healthy mating match, remember that the other prospective parent dog needs to be tested too, in order to return a conclusive result on the status of their litter.

To get a Jack Russell DNA tested for severe combined immunodeficiency, you just need to book a consult with your vet so that they can take a DNA sample from your dog, which is then sent off to an independent third-party laboratory that tests for the condition’s markers.

The laboratory then returns a verdict on the status of the tested dog (clear, carrier or affected) to their owners.