• Masajack Jack Russells

Health Testing - Why is it so important?

Before we start here, let me just put this out there - I am in no way a scientist (far from it!) so bear with me as I try to explain this!


When it comes to breeding, health absolutely must come first. When you look at puppy adverts on certain well-known for sale websites the standard 'puppy will be vet-checked' line is on pretty much all of them. For those not in the know, this most likely gives them reassurance that they will be buying a healthy puppy, however, 'vet-checked' is not the same as 'health tested'.


Jack Russell Terrier puppies in a box
This years litter from health tested dogs

With today's incredible scientific capabilities we are able to test a dog's DNA for a variety of different genetic diseases. Each breed has its own set of genetic diseases that can and should be tested for before breeding, enabling us to prevent pups being born with these debilitating and sometimes fatal conditions.


With Jack Russell Terriers there are three hereditary diseases that are known to cause problems in the breed (they should also be eye tested by a specialist vet):


Primary Lens Luxation (PLL)

Late Onset Ataxia (LOA)

Spinocerebellar Ataxia (SCA)


The genes that cause these diseases can be easily tested for by taking a swab from your dog's mouth and sending it off to a laboratory (a vet does not carry out these tests). Yes, you have to pay for it but it's not hugely expensive (£135 for all three through The Kennel Club's Combibreed package - other laboratories are available!) and it only has to be done once for each dog. The result you get back will be either CLEAR, CARRIER or AFFECTED. These diseases will not manifest in carriers of the gene and so as long as a suitable mate is chosen they should not be excluded from a breeding program if they meet other requirements. Once you have these results you can then make an informed decision about how to proceed if you are wishing to breed.


The chart below explains the risks of each combination of genes (taken from isds.org.uk).

Autosomal recessive mode of inheritance
Autosomal recessive mode of inheritance

As you can see, out of 9 combinations, 4 of them can produce affected puppies. If the status of both the sire and dam is unknown, that means there is a 45% chance of the puppies having affected status. Dogs with affected status are not 100% guaranteed (as far as I understand) to get the disease, however, it's just not a risk anyone should be prepared to take when the tests are easily available.


At the time of writing, there are 534 adverts for Jack Russell puppies on the pets4homes website. Not one of them has health tested parents and only one stud dog is advertised on there as health tested. They are also extremely overpriced but I won't get started on that issue! I've looked on that website because that, for some reason, seems to be the go-to for finding puppies (rather than finding a reputable breeder and waiting for a well bred puppy) and it upsets me so much that so little thought goes into what is being produced.


All puppies, even the designer crossbreeds that are so popular nowadays, should come from health tested parents as each registered breed has their own set of tests. A responsible breeder will only breed from health tested dogs with acceptable results. So please, if you are looking for a puppy, make sure the parents have been health tested (not just colour tested which is very popular among those wishing to make money out of so-called 'rare colours'), as well as being checked over physically by a vet. It's just not a risk that can be ignored.


Did you know about health testing before you read this post?


Let me know your thoughts in the comments below.



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