PKD positive pedigree cats
This week Mara came in and I should tell you straight up that Mara is a bit special to me.
Mara weighs next to nothing for a cat of her size and when I first saw her a couple of years ago she weighed even less.
Mara is a petite 10-year-old female cat, a gentle blue Harlequin with a flat face and mesmerising eyes which look enormous on her small body. By now, you may have also guessed that Mara is a pure Persian.
You might well wonder why I am emphasising her Persian breed. Well, occasionally, the particular breed forms a very important consideration when it comes to veterinary medical care, an example of which Mara and Polycystic Kidney Disease is a typical case.
Many of you would know that certain ailments are more predominant among certain species – both in dogs and cats. This is what is termed ‘predisposition’, which means that certain species are more prone to suffer specific ailments or diseases.
In addition to this predisposition, certain medical ailments are actually inherited. When we colloquially refer to a disease as running in the family, what we are in fact stating is that the ailment is literally written in the genes. Since inherited genetic diseases can occur in different breeds, the inverse is also true, in that different breeds may suffer from different genetic diseases.
The good news is that medical developments in recent years have meant that some genetic diseases can be tested for, using a genetic test. Put in simple terms, for certain confirmed genetic diseases, researchers have actually identified the gene which causes the particular ailment and are able to communicate this information to veterinarians who can then pass on the diagnosis to pet owners.
For those vets like myself who have been around for a while, this was regarded as science fiction when we first started out. So it’s great for us to witness the advances in veterinary medicine that today help save animal lives.
When a genetic test is not available, inherited diseases may be recognised through clinical examinations and possibly with additional further tests. Practical examples of this are the clinical examination for retained testicles (cryptorchidism), which I discussed last week, and radiology examinations for a hip defect called hip dysplasia.
These conditions are considered to be totally or partially hereditary, which means any animals that have been identified as suffering from these gentic disorders should no longer be used for breeding purposes. However, there are a number of hereditary ailments which are not so obvious.
And so it was for Mara. Mara suffers from PKD, an inherited genetic disease common in Persian cats, related breeds and exotic shorthairs. PKD is present from birth.
With PKD, what happens is that fluid-saturated cysts very gradually develop and grow in the kidneys up to a point where the normal kidney tissue is so suppressed that the cat suffers kidney failure.
As this process normally takes six to eight years, cats affected by PKD may have already been mated and had kittens several times over for multiple generations. This propagates the disease even further.
A genetic test is available for PKD. This can be done at any age from a simple blood sample or mouth swab and it identifies those cats which are PKD positive long before any clinical signs of PKD become externally visible.
This test is of great importance for cat breeders to be able to avoid breeding cats which are PKD positive; it is also of great importance to potential buyers of pedigree cats to know whether the kitten in question is progeny of a male and a female cat, neither of which are PKD positive.
If owners of pedigrees or Persian cats are not sure of their PKD status, they may be interested to perform this test as part of their cat’s routine medical check-up.
In fact, the PKD test has become a critical genetic test. When it was first made available in the UK, the percentage of positive cats found was in the region of 30 per cent. Thanks to this test and good breeding management, this disease has now been greatly reduced due the elimination of PKD positive cats from breeding programmes.
Mara was already a very small cat before she lost half her body weight. A blood check showed her kidneys were compromised and a mouth swab was sent to a specialised laboratory for genetic testing.
The results arrived within a few days, confirming that Mara is PKD positive. Mara has responded very well to kidney medication and to a special diet, and she has now almost returned to her regular weight.
She is one of the lucky ones, as PKD is a potentially fatal condition for which there is no cure. Cat owner and breeder awareness is vital to helping us control this insidious disease.
Dr Debattista is a veterinary surgeon.