Guarding Your Feline Friend’s Heart

The prevalence of heart disease in cats is on the rise, in part due to advances in veterinary care that have extended the average lifespan of our feline friends. While some heart defects may be present from birth, they often remain hidden and only manifest as the cat grows older. Other cardiac issues may develop later in life, as a result of the natural aging process or heart damage. One of the most common heart diseases that cats develop as they age is hypertrophic cardiomyopathy. In this article, we’ll delve into the world of heart problems in cats and underscore the significance of regular check-ups in maintaining their cardiac health.

Understanding Feline Heart Problems:

Just like humans, a cat’s heart serves as a muscular pump with four chambers. The right side of the heart pumps blood to the lungs to pick up oxygen, while the left side receives oxygenated blood from the lungs and circulates it throughout the body. These chambers are separated by valves that ensure blood flows in the right direction, maintaining the heart’s efficiency.

Cardiomyopathy is a condition that affects the heart muscles. It comes in several primary forms, including hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), arrhythmogenic right ventricular cardiomyopathy (ARVC), and dilated cardiomyopathy (DCM). Among these, HCM is the most common type seen in cats, with the others being relatively rare. HCM is often diagnosed in middle-aged cats, and it tends to affect male cats more than females. Cardiomyopathy can manifest with signs of heart failure and abnormal heart rhythms.

Exploring Cardiomyopathy

Cardiomyopathy, in its literal sense, means “disease of the heart muscle” (cardio for heart and myopathy for muscle disease). It encompasses four primary forms, each with its variations. The most prevalent is hypertrophic cardiomyopathy, where the heart muscle thickens, impairing its function and reducing blood flow. Arrhythmogenic right ventricular cardiomyopathy affects the right side of the heart, leading to dilation and irregular heart rhythms. Restrictive cardiomyopathy primarily affects the left side of the heart but can involve both sides, causing abnormal heart muscle relaxation. Another form is dilated cardiomyopathy, which results from stretching of the heart muscle. This type was once more common due to taurine deficiency but is now rare because taurine is added to cat food.

Causes of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy can result from conditions that force the heart muscle to work harder. Older cats with thyroid gland disease or high blood pressure, often associated with kidney issues, may develop HCM. It is also hereditary in certain cat breeds, such as Maine Coons, Ragdolls, and American Shorthairs. When there’s no apparent cause, it’s referred to as idiopathic or primary HCM.

As the heart muscle thickens, the heart’s chambers become smaller, reducing blood volume it can hold. Although the heart contracts vigorously, it can only pump a limited amount of blood. The thickened heart muscle’s oxygen supply is often inadequate, leading to cell death and the formation of scar tissue. These scars may irritate the heart, causing abnormal heart rhythms.

Understanding Dilated Cardiomyopathy

Dilated cardiomyopathy is characterised by a stretched heart muscle that causes the heart to enlarge, much like a water-filled balloon. Previously, it was more common in cats due to taurine deficiency, an essential amino acid found only in meat protein. Since cat foods are now supplemented with taurine, this condition has virtually disappeared. In DCM, the heart muscle’s contractions become weak, hindering effective blood circulation.

Causes of Other Types of Cardiomyopathy

The exact causes of ARVC and RCM remain unknown, although a genetic component may exist. RCM might be a continuation of the disease process that causes HCM, but this link is unclear. These diseases are generally treated in a similar way to HCM.

Detecting Heart Disease in Cats

Identifying heart problems in cats can be challenging because felines are skilled at concealing signs of illness. Often, there are no obvious indications of heart issues until the condition is advanced. Possible signs associated with heart disease include fluid buildup in the lungs or chest, making it difficult for the cat to breathe. Cats might also experience collapse and reluctance to exercise due to poor blood supply to the brain and muscles. Some initial signs may not appear directly related to heart disease, such as increased breathing rate, blindness, or issues with the hind legs.

Blood clot formation within the heart is another concern, as these clots can dislodge and obstruct smaller blood vessels, often affecting the hind legs (leading to paralysis) or the brain (causing neurological symptoms). Heart disease can also elevate blood pressure (hypertension), which may result in burst blood vessels in the eye and potential blindness.

Diagnosis by Veterinarians

A thorough examination by a veterinarian can often reveal heart disease. Abnormalities in heart sounds, such as a heart murmur or irregular heart rhythm, may be detected using a stethoscope. External changes in a cat’s appearance may also suggest the presence of heart disease. X-rays can reveal an enlarged or misshapen heart. In the case of HCM, most of the muscle enlargement occurs inside the heart, making external changes minimal. Blood tests, including NT-proBNP, can indicate the likelihood of heart disease. Ultrasound scans offer the most accurate diagnosis, enabling measurement of heart muscle thickness and recognition of irregular beats on an electrocardiogram (ECG).

Diagnosis of cardiomyopathy may lead to further investigations to identify underlying causes, such as measuring blood pressure to detect hypertension and conducting routine screening tests, especially for an overactive thyroid gland in older cats.

Treatment Options

If an underlying cause is identified and can be treated, your cat may recover fully. For example, treating an overactive thyroid often resolves HCM. In cases of DCM caused by taurine deficiency, taurine supplements may help the heart muscle recover. In these cases, initial heart disease treatment may eventually be reduced or discontinued as the heart heals. However, in most cases, no underlying disease is found, or there is no effective treatment. Early detection allows for long-term management, but it cannot completely halt the disease’s progression.

Long-term treatment for heart failure includes controlling exercise and using oral diuretics to reduce fluid buildup in the lungs. In DCM, drugs can be administered to increase the strength of heart muscle contractions if they are weak. Abnormal heart rhythms can be corrected with medication.

Blood clot prevention in cats with cardiomyopathy remains a topic of debate. Many veterinarians prescribe a daily dose of clopidogrel to reduce the risk of blood clots, but it may not dissolve existing clots. It’s crucial to consult your veterinarian before administering any medication to your cat.

Regular monitoring, including kidney function and blood tests, is essential for cats receiving treatment.

Life Expectancy

Predicting a cat’s life expectancy with heart disease and assessing its quality of life can be challenging and depends on the disease’s stage. Some cats with HCM can live a normal lifespan, while others may experience blood clots or heart failure. On average, cats with heart failure might survive for about six to nine months post-diagnosis, but the time span varies widely. In some cases, HCM can lead to sudden death, likely due to severe cardiac rhythm disturbances or significant emboli.

Prognosis for cats with DCM is also generally poor, with most surviving only a few months.

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