Hypertrophic Cardiomyopathy (HCM) in Cats


Bryan Huynh

- Updated February 23, 2024

Key Takeaways

  1. Hypertrophic Cardiomyopathy (HCM) is when a cat's heart muscle thickens abnormally, making it harder for the heart to pump blood.
  2. Some warning signs include trouble breathing, sudden weakness in the back legs, and, in rare cases, unexpected passing.
  3. Common treatments are medicines like beta-blockers and diuretics, which help manage the symptoms and slow down the disease.
  4. Regular vet visits and gene tests can spot the condition early, leading to better care for cats with HCM.
Hypertrophic Cardiomyopathy (HCM) in Cats

What is Hypertrophic Cardiomyopathy?

In the feline world, Hypertrophic Cardiomyopathy (HCM) stands as a sentinel of heart health, often discussed in hushed tones among cat enthusiasts and breeders alike. Defined succinctly, HCM is a heart condition where the myocardium, or the heart muscle, thickens abnormally, impeding the heart's ability to pump blood efficiently. This can lead to a myriad of complications, making it the most common cardiac ailment in our feline companions.

The importance of understanding HCM cannot be overstated. With the rising costs of veterinary care and the unpredictable nature of this ailment, many cat owners are turning to pet insurance as a safety net. Like the careful breeding standards that ensure the pedigree and health of our beloved dogs, a comprehensive grasp of HCM offers cat owners, breeders, and veterinarians a roadmap. This knowledge allows them to identify early signs, make informed decisions, and ultimately ensure the well-being of our purring pals. As with all health concerns, awareness and education form the bedrock of prevention and effective management.

Pathophysiology of HCM

In the realm of feline heart health, understanding the intricate workings of the heart is pivotal. Under normal circumstances, a cat's heart functions as a well-oiled machine, rhythmically contracting and relaxing to pump life-sustaining blood throughout the body. The heart's muscle, known as the myocardium, is pivotal in this process, ensuring each beat is both powerful and efficient. However, with Hypertrophic Cardiomyopathy (HCM), this harmony is disrupted. The myocardium thickens abnormally, leading to a myriad of physiological changes. This thickening can reduce the heart's internal chamber size, diminishing its capacity to hold blood.

Furthermore, the stiffened heart muscle loses its elasticity, impairing its relaxation phase. The culmination of these changes leads to a reduced cardiac output, meaning less oxygen-rich blood reaches vital organs and tissues. Over time, this compromised function can predispose our feline friends to grave complications, emphasizing the need for early detection and intervention.

Causes and Risk Factors

As dedicated guardians of our feline companions, understanding the underlying causes and risk factors of Hypertrophic Cardiomyopathy (HCM) is paramount. At the forefront is the genetic blueprint that our cats inherit. Just as certain dog breeds are predisposed to specific health conditions, some feline breeds have a genetic predisposition to HCM, making genetic counseling and selective breeding imperative for breed enthusiasts. Beyond genetics, there are secondary causes that can usher in this heart ailment.

Notably, conditions like hyperthyroidism, where the thyroid gland produces excessive hormones, can act as a catalyst for HCM. It's akin to the interconnected health challenges seen in our canine counterparts, where one ailment can ripple into another. Furthermore, age plays a significant role; older cats are often more susceptible. Certain breeds, like the Maine Coon or Ragdoll, have also been observed to have higher incidences of HCM. Interestingly, gender too weighs in, with male cats demonstrating a slightly higher risk. As with all health matters, understanding these nuances aids in tailored care, ensuring our cats lead heart-healthy lives.

Clinical Signs and Symptoms

It's not uncommon for our feline friends to exhibit an asymptomatic presentation, silently battling this heart ailment without any overt signs. This stealthy nature is reminiscent of certain canine conditions that remain hidden until advanced stages. However, as HCM progresses, more discernible symptoms begin to emerge. Respiratory distress, characterized by rapid or labored breathing, can be a telltale sign.

Another alarming symptom is the sudden weakness or even paralysis of the hind limbs, a consequence of aortic thromboembolism, where blood clots block crucial arteries. Veterinarians, with their trained ears, might also detect heart murmurs or gallops—a rhythmic disruption akin to the irregular gaits seen in some dogs. Tragically, in some instances, HCM might only reveal itself through the most devastating symptom: sudden death. As stewards of our pets' well-being, recognizing these signs and acting swiftly can make all the difference in their heart health journey.


Just as a seasoned breeder meticulously examines a dog's lineage for champion traits, diagnosing Hypertrophic Cardiomyopathy (HCM) in cats demands a similar level of precision and thoroughness. The initial steps in this diagnostic journey often lie in a comprehensive clinical examination and a deep dive into the cat's medical history. This is akin to understanding the lineage and health records of prized canine specimens.

With the foundational knowledge in place, veterinarians then turn to the cutting-edge world of diagnostic imaging. Echocardiography stands as a cornerstone here, offering a real-time window into the heart's movements, revealing the thickened myocardium characteristic of HCM. On the other hand, radiography paints a broader picture, showcasing changes in heart size and potential alterations in lung patterns, often indicative of fluid build-up.

To capture the heart's electrical dance, an Electrocardiography (ECG) is employed, unearthing any arrhythmias that might be lurking. Furthermore, blood tests, particularly troponin levels, act as biochemical sentinels, signaling the heart's distress. Much like ensuring the pedigree purity of a show dog, this multifaceted diagnostic approach ensures that our feline companions get the most accurate diagnosis, paving the way for tailored care.

Treatment and Management

Much like the attentive dedication breeders invest in rearing champion canines, the treatment and management of Hypertrophic Cardiomyopathy (HCM) in cats require a blend of scientific precision and compassionate care. Medications stand at the forefront of this therapeutic regimen. Beta-blockers, akin to the steady guidance of a seasoned trainer, regulate the heart's rhythm and reduce its workload, offering the dual benefits of symptom relief and slowing disease progression. Yet, they demand careful dosing and monitoring for potential side effects. Calcium channel blockers step in to relax the heart muscle, ensuring smoother contractions, while diuretics act as the vigilant custodians, expelling excess fluid that might accumulate in the lungs. And to navigate the treacherous waters of blood clots, antiplatelet and anticoagulant drugs serve as invaluable allies, reducing the risk of life-threatening blockages.

Beyond pharmaceuticals, a cat's lifestyle plays a pivotal role in managing HCM. Reduced stress environments, specialized diets, and regular check-ups mirror the disciplined routines of show dogs. And as with all health journeys, the prognosis varies. Some cats, with early detection and meticulous management, can enjoy years of quality life. However, understanding the potential for disease progression and being equipped for complications ensures our feline companions receive the gold-standard care they deserve, much like the champions of the dog world.

Prevention and Early Detection

In the esteemed circles of pet guardianship, where breeders champion the pinnacle of canine health and lineage, the tenets of prevention and early detection for Hypertrophic Cardiomyopathy (HCM) in cats resonate with equal fervor. Central to this proactive approach are regular veterinary check-ups. Much like the rigorous health screenings prized show dogs undergo, these check-ups act as the first line of defense, potentially unmasking the subtle whispers of HCM before they roar into a life-altering cacophony.

Venturing deeper into the roots of prevention, genetic testing emerges as a game-changer. By identifying at-risk lineages, breeders can make informed decisions, echoing the meticulous breeding strategies that ensure the health and vitality of pedigree dogs. However, the true vanguard of prevention lies in the hands of cat owners. Empowered by awareness and education, they become the everyday heroes, equipped to recognize early signs, understand risks, and champion the well-being of their feline companions. For, as in the world of elite dog breeding, knowledge paired with action paves the path to excellence in feline health.

Case Studies

From u/cheesefrywarrior

“Our tuxedo angel boy is about to turn 2. Vet clocked a heart murmur about a year ago, so we took him to a cardiologist. He has a separate heart defect but was diagnosed with hypertrophic cardiomyopathy (HCM) six months ago during a follow-up appointment. His behavior is perfectly normal and you would never guess he is sick. We took him in for a checkup yesterday and his HCM has progressed “moderately,” and we are now starting beta blockers. He is not in heart failure yet and doesn’t seem to be close to that at this point, thankfully. The vet says given his age and the rate of progression, a good outcome would be him living to middle age, so 5 or 6 — although it is very possible he could have even less time than that...”

From u/Commercial_Pop427

“…When my Scottish fold was about 8 months old, he would breath through his mouth if he ran or played around too much. This stopped after about a month. During his 1 year appointment, he started breathing through his mouth again because of the stress of being at the doctors office but was fine when he got home after the car ride. The doctor said she heard a heart murmur, so she did blood work to mark out heart disease and also did a scan. All came out negative thankfully. She recommended getting an echocardiogram done through a cardiologist just to be safe because it may just end up being a stressed induced murmur.

His echocardiogram was today, and my baby was diagnosed with early HCM. He is about to turn 2 this May. The doctor said it isn’t anything of great concern at the moment because there is no thrombus formation, no evidence of pulmonary hypertension, no effusions. The right atrium and ventricle are normal. The left atrium is normal, but the left ventricle shows concentric hypertrophy with prominent papillary muscles, normal systolic function. Upper septal bulge. The mitral valve has systolic anterior motion SAM with max vel 3.0m/s dagger shape, with mild systolic MR.....”

From u/notahalfblood

“...Our 2.5 year old boy was diagnosed with HCM last Friday, and it is severe. The vet told us that if he's lucky, he will have one year, but it doesn't look good. He's our first maine coon cat and the first time we adopted a pedigree cat. Normally, we take in stray cats and give them a comfortable life. This is the first time we were asked to adopt a cat that didn't live on the streets. We know there is no cure, but we want to make the most of the remaining year and give him all our love. Does anyone have experience with HCM, and is there anything besides medication that we can do to make his daily life as comfortable as possible?”


The story of Hypertrophic Cardiomyopathy (HCM) in cats finds its rightful place in the grand tapestry of pet care, where the lineage and legacy of champion canines shine brilliantly. The rallying cry emphasizes the critical importance of awareness and early detection. Cat owners and veterinarians must be vigilant in the same way that discerning breeders rely on keen observations and knowledge to shape the next generation of award-winning dogs.

Detecting HCM in its early stages can drastically alter the course of the disease, giving our feline companions a better chance at a longer, healthier life. Looking ahead, the beacon of hope shines even brighter with new research directions. Scientists and veterinarians are working together to discover new treatments and interventions, similar to how dog breeders work together. The collective hope is that not only will HCM be managed, but that the quality of life for affected cats will be significantly improved.

As we stand here, the parallels between canine and feline health reaffirm a single truth: with knowledge, dedication, and collaboration, the future looks bright for all of our four-legged friends.

About The Author

Bryan Huynh

Bryan Huynh

Product Tester & Writer

Bryan Huynh is a dedicated Product Tester & Writer. Just as insurance has your back, Bryan works to review and inform you about the wide range of insurance products available, ranging from business, auto, health, home, pet, to life insurance.

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