Monday, 5 September 2011

Health matters

One of the reasons I became interested in Norwegian Forest Cats eighteen years ago was that they are said to be a very healthy breed.  Although this continues to be true in comparison with many other breeds of cat, as our veterinary knowledge increases it has become clear that the breed does suffer from some serious hereditary diseases.  The good news is that there are increasingly reliable tests available so that it is possible for breeders to do their best to ensure that their cats are not passing on these illnesses.  The bad news is that (possibly due to the fact that they are very expensive) very few breeders in the UK take advantage of these health tests which can save heartache as well as protecting our breed.  Of course, whist awaiting test results it is nerve-wracking wondering if a treasured breeding cat will have to be neutered in the case of a positive result; but this is outweighed by the relief of knowing that inherited problems are not being passed on.

Why do so many breeders not health-test their cats?

The only reasons I can think of are:
1 – They would rather spend their money on something else
2 – They put their heads in the sand and do not really care if they pass on inherited problems
3 – They are afraid of being morally obliged to neuter one of their valued breeding cats, possibly a show winner
4 – They might feel there is a stigma attached to admitting there are health problems in one’s breeding lines.

My answer to the latter point would be that no-one buys or sells a cat with health problems on purpose; people who discover a defect or disease in their cats are to be sympathised with, and applauded that they have taken the trouble to find out.  Only if people knowingly breed from unhealthy cats, or choose not to check out the health of their breeding stock, do they deserve censure.

What are the main diseases to worry about in the Norwegian Forest Cat of the 21st Century?

I have had my own cats tested for Polycystic Kidney Disease (PKD) and my studs x-rayed for Hip Displasia  It is also wise to test for Glycogen Storage Disease (GSD IV) although this can only affect kittens if BOTH parents pass on the problem.  It does not affect cats that only ‘carry’ it.  But the most serious known threat to our breed is the hereditary disease Feline Hypertrophic Cardiomyopathy (HCM).

First and foremost we should be careful to exclude HCM from our breed. A number of Norwegian Forest Cats across the world have died of or are sick from HCM and some of these were exported from the UK. The only way to eradicate this problem from our breed is to test all breeding cats before they are mated, and to neuter those who test positive.  The way they are tested is via an ECG (echocardiogram) and there are a number of specialists across the UK - a list is available from the Feline Advisory Bureau.  HCM is a terminal condition where the left ventricle thickens and becomes enlarged over time. This is due to an abnormality of some of the cells in the heart, an abnormality that means that the cells won’t work as they should in the heart muscle and thus the normal heart cells will compensate for the abnormal cells by making more normal cells, thus causing a thickening which can be fatal. Death can be sudden, and symptoms may be mild or nonexistent. The cat can also develop a blood clot and this clot will then be carried around in the blood vessels and cause paralysis if it is carried along the large vein that runs along the back and gets split into each leg.  In this case the blood clot can’t pass and will get stuck! This is an extremely painful situation for the cat and in most cases the cat will be euthanised. The disease is thought to be caused by a mutation in one gene (this is what is believed right now, but research continues) and passed down to offspring by autosomal dominant inheritance.  (i.e. if one parent has the disease it can be passed on.  It cannot be ‘carried’ although it can be hidden for a few years.)  I have heard of several Norwegian Forest Cats in Britain suddenly dropping dead over the years.  In some cases their owners did not even carry out an autopsy.  It is possible that some of these cats were victims of HCM, as we were not fully aware of this disease here until the last few years.  Some very famous British Maine Coons have also died at an early age due to HCM.  In Europe and America there is an extensive testing programme so as to eradicate this problem, but in the UK not many breeders test their cats.  Because of this, it is not known how many cats actually suffer from HCM in the UK.  However results abroad suggest that some UK cats definitely have this disease in their lines.  It is up to us to get our breeding cats tested as that way we can eradicate HCM once and for all.

It is recommended that Norwegian Forest cats intended for breeding be tested for HCM when the cat is at least one year old but before being bred from, and then repeated annually until age 5, and once again when the cat reaches eight years, or older if something indicates that it should be done later on, for instance family history or if something looks suspicious at the last scan.  It is important to use one of the specialists listed by FAB as a great deal of training and experience is needed for a correct interpretation.  It is also important to have your cat microchipped first, so that the results can be verified and recorded by FAB.
The cost of having an echocardiogram is substantial (I paid nearly £300 per cat) – especially when you consider it has to be repeated annually.  However if you live further north the charges may be cheaper so shop around if possible.  The cats do not need to be anaesthetised unless they are very excitable, but they are shaved.  To pay that much sounds a lot; but isn’t it worth it to save the breed from being decimated by this inherited, incurable disease?  Personally I chose to ensure that my cats were healthy rather than indulging in a holiday for us humans, and it is a decision I do not regret, even though I had to have one of my most treasured queens spayed as she was given an ‘equivocal’ report from the vet, due to an enlarged papillary muscle which, whilst it probably does not indicate incipient HCM, is nonetheless an abnormality.  Luckily all my other cats were given a clean bill of health.

If buying a new cat or kitten, do ensure that the parents have tested negative within the last year and ask for copies of the test results for your records.  It is also wise to look at the health record of their ancestors, if possible, to see if HCM is in the pedigrees - this can be done by consulting various pedigree databases such as PawPeds.  Unfortunately a negative test does not mean that a cat will not be affected in the future or pass on the gene that causes HCM to his or her progeny whilst appearing unaffected, but testing together with examination of pedigrees and removal of affected cats from breeding lines is the only route we have at present.
It should be noted that HCM is something that affects many breeds of cat, and non-pedigrees too, and it is certainly not confined to Norwegian Forest Cats, which are still amongst the most healthy of all breeds.  There is currently a research project underway at the Royal Veterinary School at South Mimms with the aim of helping to eradicate HCM from Norwegian Forest Cats.  If you would like to learn more about HCM, please visit the websites below:

FAB information about HCM


Advice from the Winn Foundation

(This article first appeared in the Norwegian Forest Cat Club Newsletter, 2008, and has been updated since)

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