# HCM and breeding



## MaineCooner (Jun 26, 2011)

I have a couple of questions for the breeders out there, not specifically for breeders of Maine Coons, but breeders in general.

I have a young Maine Coon boy, about one and a half years old. Last year at his one year check up he was found to have a grade 2/3 heart murmur. I then had him heart scanned; I am very lucky in having one of the UK's leading veterinary cardiologists attached to my local practice. Unfortunately, he was found to have developed HCM, mild at the moment but he will be scanned every 6 months to keep an eye on it.

His mum and dad are both HCM gene negative (I do know HCM is multi-factorial and more complicated than that). I informed the breeder who was as devastated as I was. I sent her a copy of the cardiology report. She is genuinely a lovely lady and committed to the breed. However, and here's my question - the dad has been neutered and is therefore no longer an active stud (I think that was planned anyway) but she has on her website that she intends to breed later this year from the mum. Would you breed from an HCM gene negative queen who has produced an HCM kitten?

My second question. My youngest Maine Coon girl is just under 4 years old. I have known for a while that she had a barely perceptible grade 1 heart murmur but it was never a particular matter of concern. A couple of weeks ago, her respiration rate increased dramatically, up to about 80 per minute. Straight down to the vets and many scans and tests later, she was confirmed as having advanced HCM and to be in congestive heart failure. The cardiologist (what an absolute star she is) brought my girl back from the brink. She was stable for a week until her breathing rate increased into the 40's. Back to the vet, more scans and it's been confirmed that she has now suffered a cardiac infarction. She's stable again, acting completely normally but we know we don't have very long with her so we will make the best of the short time we have left together.

Her breeder no longer breeds Maine Coons. Her website suggests it was a decision that caused great heart ache for her, although she has continued with another breed. I also now know that one of my girl's litter mates dropped dead suddenly, aged about 2. I suspect she became aware of HCM in her lines and decided to stop at that point. That's an entirely laudable decision in my view. However, in those circumstances, would you let your kittens' owners know that there might be a problem so that they could make whatever veterinary investigations they deemed necessary?

I have no intention of turning this into a name and shame post. I think both breeders are genuine people. I would however be interested in a breeder's perspective on my questions.


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## spid (Nov 4, 2008)

From a breeders point of view I think a few things

a) My Birman was diagnosed with HCM a few years ago (before genetic tests and heart screening) - I immediately informed all kitten owners and spayed her. My cats breeder was less honest and carried on breeding her mum and dad together and denied that HCM was genetic. SO YES, I would inform all owners. 

b) Would I continue to breed a cat that had produced a litter of HCM kittens - probably not BUT I can also sympathise with the breeder, as the breeding girls and boys can cost a fortune and if she has taken one factor out of the equation, the dad, she 'should' be fine.

It's very hard. I feel it is important to gene test, I'm ambiguous about yearly scans as a) they can be incredibly stressful for the cart, b) incredibly stressful for the owner and expensive c) they are only any use after a couple of years old by which time a boy could have sired many kittens and a girl had a couple of litters, and d) they are a snap shot of one day, they don't guarantee other than that day, the cat could develop HCM the following day and the breeder carry on until the next year not knowing. Much as I feel it's very important I'm also sceptical over it's usefulness.

For me I am lucky - Minnii was diagnosed 4 years ago, given a maximum of 6 weeks to live and is still with us and in rude health.


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## carly87 (Feb 11, 2011)

I'd agree with Spid. I'd definitely be letting all kitten owners know.


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## spotty cats (Jul 24, 2012)

spid said:


> It's very hard. I feel it is important to gene test, I'm ambiguous about yearly scans as a) they can be incredibly stressful for the cart, b) incredibly stressful for the owner and expensive


I think gene testing only covers HCM1 which affects half the hcm diagnosed MC's the other half have different strains, which is why all the MC breeders I know also do yearly scans.
I've seen some scans and the cats are not stressed at all, no sedation required but that can be done.
Yes it's expensive, but it's part of making sure the cats you're breeding from are healthy.


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## spid (Nov 4, 2008)

spotty cats said:


> I think gene testing only covers HCM1 which affects half the hcm diagnosed MC's the other half have different strains, which is why all the MC breeders I know also do yearly scans.
> I've seen some scans and the cats are not stressed at all, no sedation required but that can be done.
> Yes it's expensive, but it's part of making sure the cats you're breeding from are healthy.


Oh and I agree - but . . . I also struggle with the concept of it's only valid on that one day. So you could still breed from a cat with HCM for 364 days before you realise they have it.

For me, personally on a financial basis, yearly scanning is actually going to be the straw that broke the camels back and I will stop breeding. Nearly £350 a scan plus stud fees etc, and I would need litters of 6/7 to even begin to break even, and as I can't work any more and that's not going to happen, I just don't have the money anymore. Two more litters from me and then a serious reassessment on the financial viability of this all.


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## OrientalSlave (Jan 26, 2012)

I suspect that once a scan shows HCM it will always show HCM - or DCM come to that. But of course the fact a scan comes up with HCM today doesn't mean it won't soon. I have no idea how long on average it takes to go from no signs on scan, to signs. Suspect the rate of progress can be very variable, and also an HCM scan needs the right equipment and a skilled operator hence the lists of approved places for HCM scans for the breeds that require them.

Thankfully it's not at present an issue in Orientals & Siamese.


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## gskinner123 (Mar 10, 2010)

MaineCooner said:


> I have no intention of turning this into a name and shame post.


Of course not. I don't think anyone reading would believe that was the case as both breeders, as you've described them, sound excellent.

I can't answer other than to address your last question. As a breeder no, I wouldn't contact kittens' owners to make them aware. It would be a difficult decision to make and I would perhaps keep in even closer contact than I do anyway, in the hope of picking up upon any slight mention of a potential problem.


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## jill3 (Feb 18, 2009)

I am not a breeder but I lost my Boy through HCM. I will never get over him dying at the age of 3 but if I had known that there could be a chance of him having it.
He would have had every test and treatment possible.


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## pipje (Jun 29, 2011)

I am writing this from a country where HCM is taken seriously. It is one of the tests that is practically a requirement(not officially, but not testing would make one have the reputation of a very poor quality, money minded breeder). Also, most of the good studs will not allow untested girls to mate with their boy. 

So coming from that kind of environment, my answer to your first question is no(unless it can be PROVEN that the remaining parent does not have HCM nor at risk. By proven, I dont mean just getting a new heart scan). No way. For one, it is a breeder's responsibility to breed as healthy as possible animals and secondly, by doing so, I will be a pariah whom no decent breeder will speak to/share breeding lines/ will be gossiped about etc. 

In regards to your 2nd question, I am not sure. Ethically yes- but telling isn't always good(and I don't mean for the breeder but for the kitten owners). No point causing worry for nothing. It takes away the enjoyment from the pet. It doesn't really help anyone as HCM doesn't always appear at the same time nor at the same seriousness. Furthermore, if one parent has HCM(and the other doesn't have it at all, also is NOT a carrier), 'only' 50% of kittens will have HCM


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## pipje (Jun 29, 2011)

spid said:


> Oh and I agree - but . . . I also struggle with the concept of it's only valid on that one day. So you could still breed from a cat with HCM for 364 days before you realise they have it.
> 
> For me, personally on a financial basis, yearly scanning is actually going to be the straw that broke the camels back and I will stop breeding. Nearly £350 a scan plus stud fees etc, and I would need litters of 6/7 to even begin to break even, and as I can't work any more and that's not going to happen, I just don't have the money anymore. Two more litters from me and then a serious reassessment on the financial viability of this all.


Yes, it is true if you test today, the cat could still develop HCM in the future. However, if it has it, it has it. It won't disappear(unless the specialist made a mistake).

I believe the rate at Langford is much cheaper(130 pounds or so). The HCM test is by far the most expensive test at the moment but I consider it part and parcel of breeding(for my breed). It might not be a personal benefit if for eg, a stud tests positive by 10 years old but if kittens from that line is used for breeding, it will affect them. We have a significant HCM database in nl and one can certainly see patterns


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## pipje (Jun 29, 2011)

For the op, I found this on one of my Facebook groups today(about Persians but it there is a significant section on MCs

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Sharing from the group Persian Cat HCM research

Here is Mark Kittlesons reply.

Deborah,

"First, there are no mutations that cause HCM that have been identified in Persians. Those have only been identified in Maine Coons and Ragdolls. And so far we know very little about Ragdolls.

In Maine Coons, cats that carry one copy of the gene mutation (the cats that are heterozygous) usually do not develop HCM when they are young (< 5 years of age). We don't know what happens yet to those cats when they get older. But almost assuredly there are cats that carry one copy of the mutated gene (heterozygotes) all of their life and never develop HCM. There are others that develop mild to moderate HCM and live with it and never have a problem. However, they (heterozygotes) do pass on the mutation to their offspring. Cats that have two copies of the mutation (homozygotes) usually do develop HCM and usually do that between 6 months and 5 years of age.

If you breed two cats that each have one copy of the mutation (heterozygous to heterozygous) you will get cats that are homozygous for the mutation and so ones that will most likely develop HCM. Theoretically around 25% of the kittens from this type of breeding will be homozygous. If you breed a homozygous cat to a heterozygous cat, around 50% will be homozygous (at high risk of developing HCM). If you breed a homozygous to a homozygous cat, all of the kittens will be homozygous. This is explained here - Basic Principles of Genetics: Probability of Inheritance

Heterozygous cats are sometimes called carriers. Since these cats can develop HCM that term isn't quite accurate but it's probably useful from the standpoint of thinking about what is going on for most cats.

I agree that echo screening can be costly and cannot give a breeder all of the answers. With regard to cost, the best thing to do there is to set up screening clinics where a board certified veterinary cardiologist will usually come in and do a number of cats in a day for a reduced cost. There's no way anyone should be charging over $500 to screen a cat for HCM. The problem with echo screening is that it only identifies cats that have the disease. If Persians have a mutation that is similar to the one in Maine Coons that means you're most likely identifying mostly cats that are homozygous for the mutation. But these are cats that definitely should NOT be bred. So from that standpoint it is useful. The problem is it doesn't identify most of the cats that are heterozygous."

Mark D. Kittleson, DVM, PhD
Diplomate ACVIM (Cardiology)
Veterinary Information Network
Professor Emeritus
School of Veterinary Medicine
UCDavis
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## Cerridwen (Jul 26, 2008)

I wouldn't breed parents, offspring or siblings to a cat that's been diagnosed with HCM. All these close relative are to much of a risk.

Should any of my cats develop a hereditary disease of course I contact all people that have interest in knowing about it (kitten owners, breeder of the cat etc.). I put all health info up on my website so anyone can see. It's important to be open with health issues.


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## Cats cats cats (Feb 4, 2011)

spotty cats said:


> I think gene testing only covers HCM1 which affects half the hcm diagnosed MC's the other half have different strains, which is why all the MC breeders I know also do yearly scans.
> I've seen some scans and the cats are not stressed at all, no sedation required but that can be done.
> Yes it's expensive, but it's part of making sure the cats you're breeding from are healthy.


Sadly, here in the UK , many coonie breeders hide behind the "negative by gene test" and do not scan. As the owner of a cat with HCM it saddens me and angers me greatly 

I had a conversation with such a breeder who was criticising breeders who don't gene test and was trying to pass her kittens off ( I was enquiring as a buyer) as guaranteed HCM negative because they were MYBPC3/HCM1 negative  when I shared my knowledge of the gene test *not* being a guarantee she was suddenly less willing to chat


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## MaineCooner (Jun 26, 2011)

Cats cats cats said:


> I had a conversation with such a breeder who was criticising breeders who don't gene test and was trying to pass her kittens off ( I was enquiring as a buyer) as guaranteed HCM negative because they were MYBPC3/HCM1 negative  when I shared my knowledge of the gene test *not* being a guarantee she was suddenly less willing to chat


Absolutely. My HCM boy is from MYBPC3 gene negative parents and therefore must be wild type rather than homozygous or heterozygous.


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