Tuesday 5 February 2008

HCM in Bengal Cats

anatomy of a catHCM in Bengal Cats is something to take note of if you are buying a Bengal Cat. HCM stands for Hypertrophic Cardiomyopathy. I am not a vet. I try and research things extremely carefully. I may take about 2 hours researching a topic such as this before I put "pen to paper" but what is a bit surprising (and I may be being a bit grumpy here) is that it is hard to find one place where you can find a coherent and fairly complete discussion with some statistics on this subject. I think this is a reflection on the lack of coordination in cat fancy in respect of the disease and perhaps the lack of transparency.

Note: this page was written initially in May 2008 and updated. Things change.

General cat population

HCM in Bengal cats affects around 20% of males and about 2% of females. A big difference. Why? We don't know. The disease apparently affects around 15% of the general cat population but around 0.2% of the general human population. Why? We don't know why cats are predisposed to the disease compared to humans. Do you know why? Please comment.

This page evolved which is why it is a little haphazard and has been updated a lot. Sorry.

Update 12-3-09: The fact is that there is certainly a large number of breeders who do not test for HCM in their breeding lines and do not disclose the potential problem to others and buyers and this completely understandable as it affects business (short term). But (there is always a "but"), how much HCM is in the breed and how are breeders to know unless there is transparency? It is about collective responsibility for the breed, which is good for business long term. There is a hunch that cats are dying pretty regularly from this disease. It may be more prevalent than breeders think but if breeders hide from it no one can assess the impact.

The concept of transparency need not necessarily mean declaring to the world that a cat has HCM. It could mean one breeder disclosing to another that one of her cats has HCM and this builds a knowledge base amongst breeders thereby managing it better whilst not damaging business. Clearly the best course of action in dealing with HCM in Bengal cats is to have a proper and complete database open to breeders, which provides the information. And I think that the associations should be involved in this. It needs to be enforced and the database should be near 100% to be useful.

Could it be fairly argued that a Bengal cat breeder who does not test and has her/his head in the sand on this disease, is not fit to be a breeder? Surely to not test shows a disregard for the cat and many other cats that might be born with the disease. A cat with HCM will suffer more than one that is healthy. So a breeder who continues to breed whilst ignoring this disease is potentially hurting cats. How can that person be a cat breeder? Where are the associations on this?

Update 22-3-09: On the issue of collective responsibility etc. it seems that more could be done on the basis of the number of Florida Bengal cat breeders who attended a recent University of Florida HCM testing day. The University of Florida, hold HCM clinics every three months. Apparent, most of the breeders attending are Maine Coon and Ragdoll breeders. It looks like Bengal breeders are not yet in the mood to really tackle this disease for the wider good and the good of the cats. And it is the latter issue that upsets me. If breeders don't do the testing and hide the problem as I have mentioned it indicates a less than caring attitude towards cats.

HCM is a heart disease. It causes thickening of the heart walls. This makes the heart less efficient (less flexible). This leads to a range of other medical conditions. It can go undiagnosed and your cat could it seems quite suddenly die of this disease. Or, he may exhibit symptoms such as rapid breathing, shallow breathing, gagging, loss of appetite, coughing, lethargy, breathlessness, fainting, anorexia, limb paralysis (due to blood clot blocking blood to legs) - this is painful, heart murmur, racing heart beat (200 per minute). This would be extremely distressing for the cat and human keeper. Cats can live a reasonable life with the disease however.
Bengal cat
The kind of questions I have are:- how prevalent is the disease? (i.e. the percentage of cats that have it), are there certain breeds that are more susceptible? (we know the Maine Coon has a problem with this disease, but I didn't know it was quite common, it seems, in the Bengal cat), what causes it, the symptoms and cure etc?

The truth is the vets and scientists are still researching this disease. It is genetically linked, that seems clear. This means that a cat with the gene (a mutated gene) that causes the disease can pass this on through his/her offspring. As far as I am aware the mutated gene is dominant so at least 50% of offspring will carry the mutated gene. Research apparently indicates that it is caused "by genetic mutations inherited as an autosomal dominant trait". Autosomal means that the gene is not sex related. And there are all kinds of sources which state this fact, based upon research. Apparently, there is more than one type of mutated gene causing this disease and research is being carried out to isolate these genes.

Update of transmission of this disease: The Maine Coon cat also suffers this disease (as potentially all cats can and humans too, by the way). But the Maine Coon and Bengal are, it seems at a higher risk than average. The amount of offspring who will carry HCM+ depends on whether the parent is heterozygous or homozygous for HCM, and on the basis that their mate does NOT have HCM.

The odds of getting HCM increase if you pair two HCM positive cats. It will result in 100% HCM+. These are probably the kittens being diagnosed with HCM and dying at a very young age. Here is an extract from a piece by a breeder and I am sure he will not mind me quoting him:

"The genetics are very simple here. If we use (arbitrarily) H for HCM+ and h for HCM- or normal, then for a homozygous HCM positive cat bred to a normal cat we get:

HH x hh yields 100% Hh cats which are all genetically HCM positive and will pass on the disease whether or not they show symptoms. A heterozygous HCM+ bred to a normal HCM- cat yields: Hh x hh = 50% Hh and 50% hh or half the offspring will be genetically HCM+. Remember that more than one gene may be mutated and produce HCM in Bengals."

It would seem that some breeders refer to HCM tests as showing "mild HCM" or "normal HCM". This would appear to reflect the degree of thickness of the heart wall affected by the disease (HCM causes thinkening of the heart wall - see link below).

It is vital, some breeders say, that all breeding Bengal cats be tested for HCM. In fact every Bengal cat from every pedigree should be tested if it is to be used for breeding. This is the policy being proposed to successfully deal with this nasty disease and to improve the collective welfare of the breed (see Collective Responsibility of Cat Breeders)

Update: I forgot to put this video on the page. It is ultrasound testing for HCM and PKD at a cat show in the USA:

Clearly cat breeders can and indeed must do their bit in preventing the spread of this disease by testing for HCM in Bengal cats. This does not always happen. There was an operational website (no longer updated it seems but still in existence) where cat breeders can post the results of tests. The idea was to build a database to track the disease. This website is called Bengal Pedigrees.

Testing is cheap for HCM in Bengal cats (in the US at least) at about $80 (update: see the comment at the base of this post, this figure could be misleading but was obtained in good faith and with care). So, no excuses. However some vets are more au fait with this disease than others. Where are the ones who know this disease well? - don't know. The cat need not be shaven for a test to be carried out (this is good for breeders with show cats).

The indications are that there is HCM in Bengal cats. Maine Coons are known to have it. Other breeds that are being tested are the Ragdoll, Sphynx, Norwegian Forest Cat. Does this mean that these breeds have more incidents of the disease than other breeds? - I don't know. The non-purbred cat is not immune from this disease either but it is probably less prevalent in the ordinary moggie because of the much wider gene pool. Recommendation: Ask the breeder from whom you are adopting a cat for a vet's health cert. on the disease (i.e. is the cat free of it and is that certified by an independent vet?).

HCM in Bengal Cats -- Here are some more posts on this subject that expand on it a bit:
Photo top, author is Surachit
This image taken from Wikipedia under creative commons. The image reversed in color (became a negative when downloaded so this is not an exact copy).

Photo middle, copyright and by Zanastardust
There is no connection with HCM and the Bengal cat depicted (called Mel) as far as I am aware.

  • http://www.felinewelfare.co.uk/hcm.htm
  • About.com
  • Washington State University
  • Bengal Cat Breeders

From HCM in Bengal Cats to Bengal Cats


  1. HCM testing for Bengals (or any other breed) is not inexpensive. I am not sure where you received the $80 information but it ranges from $200 to $500 per cat generally. While I believe every breeding Bengal should be HCM tested, it is NOT inexpensive for the breeder to do this.

  2. You wrote - "Autosomal means that the gene is sex related. "

    Actually Autosoaml means the gene is not sex related.

    Autosomal: Pertaining to a chromosome that is not a sex chromosome; relating to any one of the chromosomes save the sex chromosomes.

  3. Hi thanks for the comment - stupid typo - I'm sorry

  4. HCM testing is not cheap.

    While on occasion a cat show may offer testing at around $80 a cat, and breeders do take advantage of this, these opportunities are limited to cat shows, for the most part.

    Breeding females and adult breeding males often don't travel well to shows, and only a small number of cats can be adequately housed at a show.

    We typically pay between $200 to $350 per HCM screening. We have four breeding males and eight breeding queens - so we spend approximately $3500 a year on HCM screening.

  5. What is meant by "HCM - Normal", does that mean it has a genetic problem (but manageable) or does not have a genetic problem?

  6. A cat can be tested clear and then 6 months after could have it. So should we test twice a yr at the cost in the UK at around 400.00 per cat?
    I think many breeders are neutering/spaying their Bengals who have a parent or grandparent with HCM and are waiting for a DNA test which will be much more accurate then the present situation.
    I have been told by vets that the interpretation of these tests can differ from vet to vet and many other things can effect these tests e.g stress, other heart conditions, nutritionals problems, enviroment.
    HCM could also be a recessive gene that could come from a combinmation of carriers., like when we were working on the recessive white gene for whitened tummies.
    I think the problem is brought about by in-breeding, many breeders are still doing this.


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