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PostPosted: Sat Apr 19, 2008 10:45 pm 
Asian Leopard Cat

Joined: Tue Jan 16, 2007 2:47 pm
Posts: 3809
Location: UK
Some links and info re HCM

HCM - Hypertrophic Cardiomyopathy is a disease that is common in a lot of animal species, including humans.
It is common in cats and more recently has found to be common in Bengal cats.

HCM is a genetic disease.
It is an inherited autosomal dominant trait.
The abnormal genes are those involved in making heart muscle. This change to the heart can only be picked up by an echocardiogram.
"The findings on an echocardiogram characteristic of HCM include thickening of the left ventricular walls (free wall and interventricular septum), enlarged papillary muscles, and systolic anterior motion (SAM) of the mitral valve. In cats with early or mild disease only the papillary muscles may be thickened. In cats that are destined to develop more severe disease, the wall thickening increases over time. Cats with severe HCM often have an enlarged left atrium. The left atrium is not enlarged in all cats with HCM but is enlarged in all cats that are in heart failure. Occasionally a clot will be found in the enlarged left atrium of a cat with severe HCM. (i.e., the disease progressively worsens until the walls reach whatever maximum thickness they will attain)."

Read more. ... v_2006.pdf

Maine Coons

Maine Coons had a particular problem with the disease a few years ago, they have now developed a DNA test to test for one particular gene causing the disease. A lot of the work done in Maine Coons is particularly relevant to what we are now dealing with in the Bengal. ... 99/24/3172

Research requires to be carried out in the Bengal.
TIBCS have set up the Lightning fund named after Alcat Lightning Mon who had HCM and unfortunately died of the disease. You can donate to this fund via credit card or Paypal. ... #Lightning
"There is no cure for feline HCM. When detected early, however, rigorous treatment can keep even some cats with severe HCM alive and HAPPY. Lightning is proof of that. If you haven't done so yet, get your cat tested. If you don't know about it, you can't help."
Lisa, owner of Lightning - 6 months before he died aged 8 and 1/2
Research is in it's infancy and if anyone has a positive cat/equivocal cat please contact and give Jaen your cat's details to add to the TIBCS HCM database, she also would like blood samples from positive cats, to initiate research, so please contact her for details of where to send blood to.

What we can do
The only thing that can be done at present is to follow the guidelines and have all our breeding cats scanned (echocardiogram) by a FAB registered cardiologist in the UK, before their first breeding and all our breeding cats annually. A list of qualified vets/cardiologists is available here.
We can also add all cats scanned to the FAB database, they keep a list of Positive/Equivocal cats there. A list of scanned Negative cats can be seen here.

Be Aware
Be aware of your cats and any kittens you produce, even after they have left for their new homes, be aware of murmurs and any other heart symptoms, which may be present or develop.
Some symptoms/diagnoses which may be related to HCM : -
1) Breathlessness, gasping, exercise intolerance.
2) Murmurs and abnormal heart rhythms
3) Heart failure
4) Paralysis of the backlegs (Aortic Thromboembolism)
5) Syncope (temporary loss of consciousness) and
6) Death - Any cats that die without a specific diagnosis, especially if suddenly, or with some of the above signs, should be PM'd, as sudden death can occur in HCM cats.
Vets may not always be aware of the risk of HCM in this breed, let them know.

Still not convinced?

If after reading through all this and you still feel it is not indicated to scan your cats then read this:-

HCM inheritance.

If you have a positively scanned kitten/cat, no matter out of many other in the litter, then that means at least one of his/her parents has the mutant gene.

One parent who has the gene.
1. If one parent is heterozygous for the HCM gene then ½ of the offspring will have the gene. That doesn’t mean 2 kittens out of 4 kittens in a litter, it may mean in some litters all are positive or all are negative, just like ½ the population is female but in a family they can have all girls or all boys. It acts like mating a heterozygous silver to a brown, you should get half and half but sometimes all the kittens are silver and sometimes all are brown but usually you get a mixture.
2. If one parent is homozygous for HCM, all offspring will be affected and have the gene. Some will scan positive some negative, unfortunately.

Two parents have the gene
1. All offspring will have the gene. Again some will scan positive some negative, unfortunately.


Negatively scanned cats.
1. May not carry the gene, will never scan positive or develop HCM and will not pass the gene on to their offspring.
2. May have the gene and convert to a positive scan as they age or die first of HCM. They will pass on gene to offspring.
3. May have the gene and never convert to a positive scan nor will die of HCM. They will pass on gene to offspring.

Positively scanned cats.

1. Heterozygous - Will have the gene, and pass it on to half of their offspring unless mated with another cat who has the gene, in that case all offspring will be affected.
2. Homozygous – will pass the gene on to all of their kittens whether mated to a cat that has or does not have the gene.

Two negatively scanned parents can produce positively scanned offspring, but the parents are only scan negative and not gene negative. See above.

Two positively scanned parents will always produce kittens having the gene, but the kittens may not show it on scanning, till later, if ever, but they will pass it onto their progeny whatever their scan results show.

Genetic testing
Once we get the genetic testing then it will be possible to test for a specific gene so negative and positive will have more meaning, as you cannot convert from positive gene to negative gene or vice versa. Positive genetic tested animals will definitely have HCM and will pass it on to their progeny. We can mate those with negative genetic individuals and we will be able to genetically test the kittens and then we can make decisions on our further breeding from there.

Once we have the gene test, we will still need to scan our cats unfortunately to pick up other causes of genetic HCM. As not all HCM cases will be found to be carrying the same genetic mutation, some will be negative on genetic testing, but will still produce positive HCM offspring on scanning, and may themselves be positive on scanning.

In the Maine Coon breed, it is a specific request they have made to their breeders not to discard all genetically positive cats, but only to discard any that are proved homozygous from their breeding programs, otherwise the gene pool becomes very small. Heterozygous positives are bred to negative cats and the resulting progeny tested.

In the Bengal breed, at present, it is impossible to source truly negative cats to mate positive cats to, so it is a far more risky strategy, one which I think, few people would wish to undertake.


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