Heart Murmurs in Cats: What You Should Know About Hypertrophic Cardiomyopathy (HCM)
Hearing that your cat has a heart murmur can be concerning, especially since cats are often masters at hiding illness. One of the most common reasons we hear a heart murmur in cats is due to a condition called hypertrophic cardiomyopathy (HCM)—a disease that thickens the walls of the heart and affects how efficiently it pumps.
What is HCM?
In hypertrophic cardiomyopathy, the muscular walls of the left ventricle (the main pumping chamber of the heart) become abnormally thick. This reduces the heart’s ability to fill with blood and, over time, can lead to heart failure or dangerous blood clots. HCM is the most common form of heart disease in cats, particularly in breeds like Maine Coons, Ragdolls, and American Shorthairs, but it can affect any cat—purebred or mixed.
What symptoms should I look for?
Unfortunately, many cats with HCM don’t show obvious signs early on. That’s why regular wellness exams with your veterinarian in Fargo, ND are so important. We often first detect HCM by hearing a new or louder heart murmur during a routine checkup.
As the disease progresses, signs may include:
Labored or rapid breathing
Lethargy or hiding more than usual
Sudden weakness in the back legs (a sign of a blood clot)
Loss of appetite
Collapse or open-mouth breathing (a veterinary emergency)
What diagnostics do we recommend at TRVH?
If we detect a murmur or suspect heart disease, we may start with chest X-rays to look for signs of heart enlargement or fluid buildup. However, a definitive diagnosis of HCM requires an echocardiogram (ultrasound of the heart), performed by a veterinary cardiologist. We typically refer our patients to the Animal Emergency and Referal Center (AERC) in Oakdale, MN.
Treatment and monitoring
There is no cure for HCM, but early detection and management can dramatically improve outcomes. Cats with mild cases may only need monitoring every 6–12 months. Others may require medications such as beta blockers or diuretics to support heart function and reduce the risk of complications.
Cats with HCM also need to be monitored closely for signs of arterial thromboembolism (ATE)—a blood clot that can lodge in the back legs and cause sudden paralysis and pain. This is a life-threatening emergency, and cats with HCM are at increased risk.
Stay informed—early care is essential
If your cat has been diagnosed with a heart murmur, or you're noticing changes in breathing or energy levels, we’re here to help and guide you through every stage of care with compassion and expertise. Don’t wait—schedule a visit with your vet clinic Fargo, ND today.
