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The HCM Clinic Evolution

By Emily Greene, CitizenKat Sphynx, www.citizenkat.com, September 2013

This article was written for the Canadian Cat Association Newsletter Sept 2013.

This article may not be reproduced without permission.


When I started breeding and showing cats in 2003 – Very few breeders had heard of a heart disease called Hypertrophic Cardiomyopathy (HCM).  Even fewer scanned their cats for this disease.  As I was going to be a Sphynx breeder, I spent a lot of time learning about potential health issues in Sphynx.  A few Sphynx owners had told me their Sphynx had died young of heart issues - usually of HCM. I wanted to try my best to mitigate any health issues in my program so I researched HCM thoroughly.


Hypertrophic Cardiomyopathy (HCM) is found in all cat breeds and is the most common heart disease found in all domestic cats. HCM is a thickening of the heart's left ventricle wall. This is generally a genetic disease, but there can be secondary causes such as thyroid issues.  Some cats that have heart conditions show no outward symptoms (ie heart murmur) when checked by a non-specialist vet.  It is often known as the silent killer as some cats have no symptoms until they in cardiac arrest.

After my research, I knew I needed to do regular echocardiograms on all my breeding cats. And… most importantly – these exams had to be done by a board certified cardiologist.


MY FIRST EXPERIENCE SCANNING: On Saturday, June 19, 2004, I drove two hours with my first breeding female “Aviah” to get her heart scanned at Chesapeake Veterinary Cardiology Associates (CVCA) in Towson Maryland.  I was as nervous as could be and really had no idea what to expect. The scan process itself was easy – first, the cardiologist completed a physical examination, listened to the heart. After that,  we were taken into a darker room where the cat is laid on its side on a table with a hole in it. Then the ultrasound probe is put up to the chest.  The echo itself was about a 4-5 minute procedure.  Fortunately – my cat Aviah at 1 year old, did have a normal scan. The cardiologists were so nice and willing to answer any questions.

It was quite an experience!  I hardly slept the night before due to nervousness… and then feeling of relief after the fact… and then knowing it will happen again in about a year. I was very new to the process of HCM scans and had a lot to learn. I was unaware that heart scans have interpretation involved.  Not all scans are black and white. Sometimes they can have something trivial wrong with it but the heart is still considered "normal" by a cardiologist. Another thing I was shocked about was that many cats have stress murmurs at the vets!


Over the years, I continued to scan my breeding cats at CVCA in Towson. There was a lull in the CVCA-Towson HCM clinics for awhile, so I waited… and waited.  No one was stepping up to the plate, so I decided I would ask if I could set a clinic up because I needed cats scanned! CVCA said yes and gave me a date to set up times.  The set-up entails taking all the cats’ information and setting up times prior to the clinic so all the information can be entered into the CVCA system.  For almost 6 years now, I have been setting up HCM clinics in the Maryland area. It does take time & is volunteer work, but it is rewarding to know these clinics help better each of the dedicated breeder’s program.   There are about 35-40 cats that get scanned at these quarterly discounted weekend clinics.  It is not just Sphynx that go to these HCM clinics… but Bengals, American Shorthairs, Ragdolls, Turkish Angoras, Persians, Cornish Rex, Devon Rex, Maine Coons.  HCM is not just a Sphynx disease as some purport it to be.


Steven L. Rosenthal DVM Diplomate ACVIM Cardiology states:

"The ideal time to diagnose and start to manage cats with hypertrophic cardiomyopathy and other feline heart diseases is at a time that symptoms are not present.  There are a number of ways to screen cats for heart disease with the current gold standard being via echocardiography.  In the mid 1990's the doctors of CVCA starting screening breeding cats for HCM and we diagnosed almost one third of the cats with HCM.  We have seen those percentages reduced through active screening of breeding cats and their relatives.  Currently we find a much lower percentage of affected cats and when cardiomyopathy is found it can often be managed medically for many years with the goal of improving the quality and quantity of the lives of these affected cats. "

Scanning does help breeding programs immensely. I am and always will be an advocate for regular HCM scanning.  Pet buyers and breeders alike should seek to support breeders that scan regularly and are open about their results. If you are going to purchase a kitten as a breeder or as a pet, do not be afraid to ask for the HCM scan of the parents.


Some will argue that the cat’s “normal” scan is only good for today. And they are not wrong except they leave out one very important part!  If the cat has a genetic heart issue, removing that cat from a breeding program is so important.

These are my personal examples of how scanning & pedigree study has helped my breeding program.


NOT HCM??: Kayla - so healthy, not ever a cold and very active. When I took her to be scanned she was diagnosed by the cardiologists "NOT FOR BREEDING"  because she has mitral & tricuspid valve dysplasia. The cardiologists told me that her offspring could have it worse than Kayla and require medications. If I had not taken her to the cardiologist, I would have never known and might have bred these issues. Kayla does not have HCM, but it is still thought to be a genetic heart defect.

HCM POSITIVE: My breeding partner and I purchased a male cat named Earl. At 13 months old, Earl appeared to be in excellent health and we were shocked to learn that he was HCM positive. Thankfully, he was never used in a breeding program to perpetuate this problem. Sadly, in July 2012, at just 3.5 years old, he passed away in a loving pet home.

MEDICAL BENEFITS FOR HCM POSITIVE CATS:  In Spring 2013, my breeding partner contacted me with news that makes your heart sink. She let me know several cats she had bred and placed as pets had heart murmurs. These kittens were all out an outside stud male from Georgia. As far as we knew, that male was only scanned by his breeder one time.  The one and only kitten I had from this stud cat, Carlito, was altered, petted out and not used in my breeding program. He was now 4 years old. I immediately contacted his owners and let them know the news. They are truly great pet owners and took Carlito to the board certified cardiologist at CVCA to get scanned within 2 weeks. 


    When the day came - the news was not good - Carlito was HCM positive. It was not mild either, but moderate. Carlito was put on appropriate medications and needed a recheck in 6 months. The recheck would be very telling if the medicine was able to help Carlito. The medicine can help but it does not work in all cases.


     On Sept 16, 2013, Carlito went in for his 6 month recheck and the owners got excellent news. His heart function had improved and so the medicine was working so there was a very good prognosis! It was amazing news. (The other two cats that had murmurs,  Smokey & Bandit, were also HCM positive, theirs was more mild.) 

     Update: June 12, 2015 Carlito visited CVCA and his heart issues have continue to stabilize with medication and he continues to do well.

   HCM is very scary diagnosis, however, proper medical treatment can improve the cat’s heart function and thereby increase its lifespan.

IMPORTANCE OF PEDIGREE:  Another Sphynx I had, Claire, was already altered and not used in a breeding program because of a very risky pedigree. She was my forever pet and I wanted to scan her to ensure she did not need medicine. Much to my surprise - her scan was normal.  Six months later on a beautiful Saturday afternoon on Sept 15, 2008, Claire appeared to be sleeping on the bedroom chair. I went over to touch her and she was cold. I touched her again in shock and disbelief.  I screamed. And screamed. I could not believe Claire was gone.  I was in hysterics and almost did not get a necropsy done.  I realized I had to know even though I did not have her lines any longer.  When the necropsy report came back, she had a cardiac arrhythmia and her heart was 1.5 times larger than it should have been for a cat her size.


     This is an extremely important example to show how breeders must pay attention to the pedigree as well as scan. Scanning is only one tool. The pedigree is another.  Some may have ignored this pedigree risk and bred Claire with a clear scan.


    Everyone is going to have a different risk threshold and each individual needs to evaluate that carefully.


WHAT IS IN THE HEART:   Motives for scanning do matter. If one scans to market their cats for sales, there is the possibility that only the good will be reported.  Timeliness of the information is important as well.  Sometimes people do not tell you about the scans or share the appropriate documents. Make sure you see the actual documents for the scans or ask if you can speak with the cardiologist to confirm the information. There are databases out there. Unless it is run by an unbiased, non-breeder, do not trust it. I am not sure about other breeds, however I know in the Sphynx databases, there are definitely mistakes. Some cats are positive and marked not so.


HCM POSITIVE CATS IN A LINE MAKE A BREEDER BAD?  HCM positive cats alone do not make a breeder “bad” or one to avoid.  Even proactive breeders will have HCM pop up as scanning is only a tool. Ragdolls and Maine Coons have the DNA testing however the DNA testing is not a perfect tool either as there are thought to be many HCM mutations.


     As with most things, it is the actions taken that differentiate a conscientious breeder from the rest. When this does happen, a caring breeder needs to assess the risk and takes action to mitigate the risk. These actions include informing those with related lines immediately and possibly altering related cats and/or using them with more caution.

    A good breeder wants to know how pets in pet homes are doing. Truthfully, this is the best gauge of how a breeding program is going.

BOTH MY CAT'S PARENTS ARE TESTED NORMAL, HOW CAN MY CAT HAVE HCM? Unfortunately, the HCM scanning and pedigree study is not a perfect tool. You can get an HCM positive cat out of two negative parents. The transmission is thought to be autosomal dominant with variable expression. The variable expression is how this disease gets tricky. This means a parent can have the gene but never express it in its lifetime or express it much later on. But this gene can be passed along to an offspring and the offspring can develop HCM.  This variability makes it harder to detect.




HCM scanning is something that is really beneficial to all breeds. It is not a perfect tool, but it does help the breeders, the pet buyers and the cat's themselves. As time as gone on, more and more breeders of all breeds realize this and now scan for HCM. 


I hope my very personal experiences show how important it is to take breeding cats to the cardiologist and demonstrates that breeders cannot rely on the scan alone. Responsible breeders must remain cautious in breeding programs and consider the pedigree as well. Those who scan, share the information about their lines with those they work closely with, and are cautious literally help avoid a lot of heartache.