Thread: HCM gene testing- are we wasting our time?

There have been a couple of relatively small studies to look at the outcome of HCM positive MCs. I will have to look them up because I cannot seem to find the papers on my machine right now, and the better one is hard to find online I believe. If you do related research, you should be able to find them. Primary author to search on is Kittleson and also of course Meurs (for older papers).

I have read these papers carefully as we have a heterozygous female, who is now nearing age six. She was echoed at four years by a vet cardiologist and showed no heart changes. One of our breeders has a hetero male who was around eight I think when our Allie was echoed (done together), and he has definite heart changes (though no symptoms).

More recent paper showed outcomes for hetero cats being mixed, some have clear HCM changes and others do not.. Study was not to be able to say if any hetero cats live a normal lifespan without health issues, though. Outcomes for homozygous cats generally have been shown as dire: virtually absolute early death sentence (some before age two as I recall).

The only reason to be breeding hetero cats, in my opinion, is if this is required for genetic diversity or some particular quality that one can get only from HCM positive MCs. Having had a cat that was ill with HCM for several years and died from it, there is no way in the world that I would ever spend a fairly large sum of money to buy a cat that I knew had a risk factor for this disease. Yes, the one known HCM mutation is hardly the only factor in health, but it is a very unpleasant disease for both the cat and the owner, so why would you not want to do as much as possible to eliminate that risk? Makes no sense to me! Also, the HCM gene test is hardly the only genetic and other type of health test that responsible breeders are doing (e.g., echo tests, PKD testing).

Potential owners of mutation-positive MCs should also be aware that there are no good treatments for HCM in cats. Current best practice (at least in US) is not to do any treatment on symptomless cats regardless of heart structural changes seen on echo. Generally the primary treatment once symptoms develop (congestive heart failure) is diuretics. My understanding from vet cardiologists (as of a couple of years ago at least) was that none of the other treatments that have been recommended (beta blockers and calcium channel blockers) have been shown to extend lifespan. Having said that, our MC mix lived four years post congestive heart failure, which is considered an extremely long period of time. He was on a calcium channel blocker the entire time. Cardiologist told me it wouldn't be helping him. I asked her how he had then managed to live so long post CHF not using diuretics for most of the time. She could not say. So, unfortunately, we see that little is really known about treating HCM in cats. I can tell you that Karma's last few hours of life were horrible for him and us.