08/25/2026
While this post is from a Maine C**n Cattery— it is 💯 relevant in the Sphynx world, too!
Can we have a critical-thinking conversation about HCM testing? 🫀
Because I think two things can be true at exactly the same time:
HCM screening is incredibly important.
AND…
We sometimes give HCM screening far more predictive power than it actually has.
We just drove 12 hours round trip yesterday to have some of our breeding cats screened. So before anyone mistakes this for an argument against testing… it absolutely is not.
We test because when there is a tool available that gives me more information and can help reduce risk in my breeding program.
I also hate paying large amounts of money to be told “everything is perfectly normal” when my gut instinct already felt that based on all the data we already had from family history.
But I also think buyers deserve to understand what that tool actually tells us…and, maybe more importantly, what it doesn’t.
🧬 DNA testing
There is a known Maine C**n-associated HCM mutation in the MYBPC3 gene that we can test for.
That’s valuable information.
But a negative DNA result does not mean a Maine C**n is genetically incapable of developing HCM.
It means that cat does not carry that particular known mutation.
HCM has been documented in Maine C**ns who test negative for that mutation.
🫀 Echocardiograms
An echocardiogram allows us to look at the actual heart and determine whether there is currently evidence consistent with HCM.
Also incredibly valuable.
But here’s the distinction I wish we talked about more:
An echo tells us what that cat’s heart looks like at the time it is examined.
It cannot promise what that heart will look like at 3, 5, 8 or 10 years old.
HCM is progressive and can develop later, which is precisely why repeat screening is recommended.
And THAT is where HCM testing becomes a little arbitrary to me.
Not arbitrary because the testing is useless.
Arbitrary because of the amount of certainty we sometimes attach to a single result taken at a single point in a cat’s life. Especially when breeders use HCM testing as their evidence in their health guarantees to claim your kitten is proven healthy.
A 12-month-old cat with a normal echo isn’t suddenly stamped:
CERTIFIED NEVER TO PRODUCE HCM KITTENS.
That’s simply not what the test means.
So what does this mean if you’re BUYING a Maine C**n?
This is where I really want buyers to use critical thinking.
You’ll often hear:
“Never buy from a irresponsible breeder who doesn’t HCM echo.”
But I don’t think tested = guaranteed safe and untested = dangerous is an intellectually honest way to explain HCM risk.
If the parents have normal echocardiograms, that gives you additional information about those cats at the ages they were screened.
That’s GOOD.
It does not mean their kittens cannot develop HCM.
Likewise, if a parent hasn’t had an echocardiogram, you have less information about that parent’s current cardiac phenotype.
That matters.
But the absence of that one piece of information does not, by itself, tell you that the parent has HCM or allow anyone to accurately tell you the individual kitten sitting in front of you is destined to be at higher risk.
Unknown is not the same thing as positive and I would even argue not even irresponsible if you know pedigree history.
And normal today is not the same thing as guaranteed normal forever.
Those distinctions matter.
So instead of asking a breeder only:
“Do you HCM test?”
I’d dig deeper.
Ask about the parents, siblings, grandparents and previous offspring.
Has HCM appeared anywhere in the close family?
Ask whether the breeder stays in contact with families and tracks health problems that appear years after their kittens leave.
Ask what happens if one of their breeding cats …or one of its offspring…is later diagnosed with HCM.
Do they change their breeding decisions when new information becomes available?
Personally, I’d rather evaluate the entire health picture than see the words HCM tested on a website and stop asking questions because that’s sufficient.
That’s what responsible breeding looks like to me.
Not chasing a magical piece of paper that promises something science cannot actually promise.
It’s stacking information.
🧬 DNA testing tells me whether my cat carries a known HCM-associated mutation.
🫀 Echocardiography tells me whether there is evidence of HCM at that point in the cat’s life.
🔁 Repeat screening tells me whether that picture changes with age.
🌳 Pedigree and family history tell me what’s happening throughout the line.
🐾 Following the kittens we produce tells us what’s actually happening in our offspring over time.
None of those things individually can promise me that I will never produce a kitten that develops HCM.
Together, they give me a better picture and allow me to make more informed breeding decisions.
That’s risk reduction. Not risk elimination.
And I think we do buyers a disservice when we pretend otherwise.
“My breeding cats had normal HCM screenings, therefore my kittens cannot develop HCM” is not a promise science allows a breeder to make.
What I can promise is:
“I will use the tools available to me. I will understand their limitations. I will continue gathering information as my cats and their offspring age. And when new information changes the risk picture, I will change my breeding decisions accordingly.”
That’s why I can simultaneously believe HCM screening is necessary while recognizing that some of the certainty we’ve built around it is arbitrary.
A test result is valuable data and isn’t a crystal ball.
And perhaps buyer due diligence shouldn’t be finding the breeder who promises you there’s no risk.
Maybe it’s finding the breeder who understands the risk well enough not to make that promise in the first place.
Xo,
Alicia + Darren
