Last Updated: 06/05/2025
Has your cat been diagnosed with heart disease? Read through our guide for everything you need to know about cardiomyopathy in cats.
Author: Dr Carla Paszkowski BVSc (Hons)
Reading Time: 24 minutes - medium read
Has your cat been diagnosed with heart disease? Or perhaps you are a prospective kitten owner researching your favourite cat breed, but have discovered they are a breed prone to developing cardiomyopathy? This guide should provide you with everything you need to know about cardiomyopathy, the most common heart disease in cats.
1. What is cardiomyopathy in cats?
Cardio = heart
myo = muscle
pathy = disease
Cardiomyopathy is the name given to a disease affecting the muscle of the heart itself. Cardiomyopathy it is the most common cause of heart disease in cats. It refers to disease of the heart muscle within the ventricle wall.
Source: VCA Hospitals
To understand feline heart disease, it's important to understand the anatomy of the heart. Just like humans, cats have four chambers in their heart - the two lower chambers are called the ventricles and the two upper chambers are called the atria. The heart has a right and left side, each containing one atrium and one ventricle, with valves at the junctions to control the direction of blood flow.
The walls of each chamber are made of smooth muscle which contract to eject blood out of its respective chamber. The left ventricle has the largest muscle, as this is where freshly oxygenated blood is pumped to all the organs and body parts.
Did you know? Humans and dogs often suffer from a disease of the heart valves, which causes leakiness and murmurs. However, this form of heart disease is rarely seen in cats.
Cardiomyopathy may occur secondary to other conditions, including:
⢠Diseases such as Hyperthyroidism, high blood pressure, or acromegaly
⢠Nutritional causes such as taurine deficiency
⢠Parasites - namely, heartworm
⢠Cancers including Lymphoma
⢠Toxins - particularly some medications
⢠Breed disposition - genetic defects are recognised in Maine Coons and some other cats
Cardiomyopathy refers to any disease where the heart muscle itself is affected. There are three main types:
Hypertrophic Cardiomyopathy (HCM). This is the most common form. It occurs when the ventricle muscle thickens to the point that it can no longer relax, pump and fill the ventricle adequately. HCM usually occurs in the left ventricle.
Restrictive Cardiomyopathy (RCM). This condition involves the buildup of scar tissue on the inner lining of the heart, which leads to reduced filling and pumping. It is lesser understood than DCM and HCM.
Dilated Cardiomyopathy (DCM). This is where the muscle wall of the heart becomes thinner than usual, the heart enlarges, and the muscle cannot pump effectively.
Heart disease can occur in any cat breed, but is seen with more frequency in certain breeds. If you are considering adopting a kitten from one of these breeds, you should check if the breeder has selected lines free from heart disease. DNA tests are also available that can help rule out the gene in question.
1. Maine Coon cats are prone to Hypertrophic Cardiomyopathy (HCM). Affected cats may begin to develop problems as early as 3 months of age. It's estimated that 33% of Main Coon cats have a genetic abnormality related to HCM.
2. Persian Cats are also predisposed to HCM and have a high incidence of the disease.
3. Ragdolls are also predisposed to HCM and have a moderate incidence of the disease.
4. British Shorthair cats are predisposed to a less serious form of HCM.
5. Siamese cats commonly are affected by other forms of heart disease, including patent ductus arteriosus (PDA) and dilated cardiomyopathy (DCM).
Cardiomyopathy may occur in either males or females, but is more common in male cats. The first signs of the disease often appear in older animals, but it may occur in young cats if they have a severe congenital form of the disease. Symptoms can be hard to observe unless full blown heart failure is occurring, which is why heart disease is known as 'the silent killer'.
Trouble breathing. This may present as rapid, laboured, or open-mouthed breathing. Respiratory distress is due to fluid buildup - particularly in the cavity around the lungs in a condition known as a pleural effusion.
Hind leg weakness or paralysis. This is often the result of a blood clot. In cats with HCM, blood clots often form at the base of the aorta which cuts off blood supply to the hind legs. This is a medical emergency.
Coughing, retching, or vomiting. Cats cannot cough as easily as dogs can, so they sometimes vomit instead.
Reduced energy, lethargy and listlessness
Poor circulation. The cat may have cold extremities, bluish footpads or nail beds, and grayish gums or tongue.
Loss of appetite
Restlessness
Diagnosis of heart disease in cats requires a veterinary examination and diagnostic tests. Your vet may complete all or some of the following tests.
⢠A full physical exam with a chest auscultation. Your vet will listen to your cat's heart for any murmurs or abnormal sounds.
⢠Blood pressure measurement
⢠Electrocardiogram - this test uses electrodes to measure electrical currents in the heart muscle to see if there is any abnormal rhythms
⢠A full physical exam
⢠Xrays of the chest
⢠Cardiac Ultrasound
Firstly, your vet will need to treat any life-threatening symptoms. If your cat has a pleural effusion (fluid in the cavity that surrounds the lungs) this will need to be drained. Likewise, any clot that is impeding mobility will need to be dissolved with medication immediately.
Once any emergencies have been addressed, long term management can begin. While heart disease cannot be cured, it can be managed with oral medication. Medication can be used to help the heart function better, normalise the rhythm, or reduce blood pressure. Depending on the drug required, they may be available in pill form, liquid form, or in gels that can be applied to the skin of the ear. Your cat will need to be treated with medication for life.
Drugs that may be used to treat heart disease in cats include:
1. Beta-blockers such as propranolol or atenolol, which slow the heart rate to reduce oxygen demand on the heart.
2. Calcium-channel blockers - similar to beta blockers as they helps the heart muscle to relax. They also reduce the strength of the heart's contractions to allow for more rest.
3. ACE-inhibitors (ACE stands for angiotensin-converting enzyme) such as benazepril, ramipril, enalapril, or ARBs (angiotensin receptor blockers) such as telmisartan. These help block the renin-angiotensin-aldosterone-system which may help manage the clinical signs of heart failure.
4. Diuretics such as furosemide/frusemide. These help reduce the signs of congestive heart failure by removing fluid build up around the lungs.
Ongoing care with regular vet check ups will be necessary to monitor your cat's progress and response to medication. The good news is that many cats
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