How Big is a Cat’s Heart?

One of the most fascinating aspects of my work involves peering into the wonderful world of our cats. Today, I am eager to share some insights with you on one of the lesser-known facts about cats: the size of their heart. At first, this may seem to be an unusual topic for discussion, but understanding the size and function of a cat’s heart can greatly impact our comprehension of their overall health and well-being.

In this article, we will explore the dimensions and characteristics of a cat’s beating heart, delving into the various factors that can affect its size.

How Big is a Cat’s Heart?

When discussing the size of a cat’s heart, there are a few things we need to take into account. The breed, age, and health of the cat are all crucial factors that can affect heart size. However, it’s also vital to ensure we’re measuring the heart accurately.

Average Size

On average, a domestic cat’s heart is about 2.7 to 3.1 inches (7-8 cm) long, weighing approximately 0.44 to 0.66 pounds (20-30 grams). This size is roughly similar to that of a human’s clenched fist. But, as we are aware, the heart size can vary between individuals based on the factors mentioned above.

Age and Heart Size

Kittens and young cats will invariably have smaller hearts. The heart grows with age until the cat reaches maturity, typically around 1-2 years old. From here on, barring any health issues or other abnormalities, the heart size will remain comparatively stable throughout adulthood.

Breed and Heart Size

Differences in breed can contribute to variations in heart size. Larger cat breeds, such as Maine Coons and Norwegian Forest Cats, can have slightly bigger hearts due to their overall larger body sizes. On the other hand, smaller breeds tend to have proportionally smaller hearts.

Health and Heart Size

Health conditions can significantly impact a cat’s heart size. Conditions like heart disease, both congenital or acquired, can cause heart enlargement (cardiomegaly). Cardiomegaly is a serious condition which can lead to various other health complications.

Importance of Heart Size

As a veterinarian, understanding the standard heart size for a particular cat allows us to identify potential health problems sooner. Regular vet visits, which often include heart checks, are crucial to maintaining your cat’s optimal health.

anatomy and physiology of a cat’s heart

Anatomy of a Cat’s Heart

Just like humans, cats have a four-chambered heart, divided into two atria and two ventricles:

  • Atria – The two upper chambers, the right and left atrium, are the points where blood enters the heart.
    • The right atrium receives oxygen-poor blood from the body and sends it to the right ventricle.
    • The left atrium collects oxygen-rich blood from the lungs and sends it to the left ventricle.
  • Ventricles – These are the two lower chambers of the heart.
    • The right ventricle pumps the oxygen-poor blood to the lungs, where it gets oxygenated.
    • The left ventricle pumps the oxygen-rich blood out to the body, supplying tissues and cells with the oxygen they need to function.

Physiology of a Cat’s Heart

Now that we’ve covered the structure let’s talk about how these parts function together to keep your kitty active and healthy.

  1. Circulation – A cat’s cardiovascular system follows a double circulatory system. This means that the blood circulates twice through the heart for a full circuit of the body: once for pulmonary circulation (heart to lungs and back) and once for systemic circulation (heart to body tissues and back).
  2. The Beat – The cat’s heart begins to beat with the filling of the atria with blood. Once filled, the atria contract (this is your lub), pushing the blood into the ventricles. Next, the ventricles contract (and that’s your dub), driving blood out of the heart to either the lungs or the rest of the body.
  3. Regulation – The speed and strength of each beat are regulated by electrical signals from the cat’s natural pacemaker, known as the sinoatrial (SA) node, located in the right atrium. These signals originate in the SA node and move through the atria, causing them to contract and then reach another node. This atrioventricular (AV) node passes the signal to the ventricles, causing them to contract.

Monitoring Your Cat’s Heart Health

Keeping an eye on your cat’s heart health is an essential aspect of maintaining their overall well-being. Trust me, it’s not as tough as it sounds! Here’s a simple guide to help you monitor your cat’s heart health.

Regular Vet Visits

First and foremost, ensure your cat has regular check-ups with a vet at least once a year. The vet will listen to your cat’s heart to detect any abnormal rhythms or murmurs. This is called auscultation. If anything unusual is noticed, additional tests like echocardiograms (an ultrasound for the heart), electrocardiograms (which measure the heart’s electrical activity), or x-rays might be required.

Check Resting Respiratory Rate (RRR)

A slight increase in a cat’s resting respiratory rate can be an early sign of heart disease. Observe your cat when it’s calm and relaxed, ideally when it’s asleep or resting. Count how many times the chest rises in 60 seconds. A healthy cat takes around 15-30 breaths per minute. If you frequently notice a resting rate over 30, schedule a vet visit.

Watch for Signs of Distress

Look out for these signs:

  1. Breathing difficulties or sudden breathlessness: This could look like open-mouth breathing or panting, which is unusual for cats. Keep an eye out for abnormal abdominal movement while breathing.
  2. Chronic coughing – While dogs with heart disease often cough, it’s less common but not unheard of in cats.
  3. Fatigue or lethargy – If you notice your usually playful kitty showing less interest in activities, getting tired easily, or sleeping excessively, there could be an underlying issue.
  4. Loss of appetite or weight – If your cat starts ignoring its favorite treats or if their weight suddenly drops, it’s time for a vet check.
  5. Sudden paralysis or pain – Especially in the hind legs, could signify a severe medical emergency known as saddle thrombus, often related to heart disease.

Maintain a Healthy Lifestyle

Keep your pet active and on a balanced diet. Avoid over-feeding and under-exercising. The more agile your cat is, the healthier its heart likely is.

What is the difference between a cat’s heart and a human heart?

Size and Positioning

Firstly, the size of the heart relative to the body is smaller in humans as compared to cats. An average human heart is about the size of a fist and weighs around 0.6-0.8 pounds (270-363 grams), while a cat’s heart is roughly the size of a large grape or a small plum, weighing around 0.04 to 0.06 pounds (20-30 grams).

The position of the heart within the chest cavity is slightly different as well. In humans, the heart is situated centrally, tilted slightly to the left. However, a cat’s heart is positioned more centrally within the chest cavity.

Rate of heartbeats

The heart rate in both cats and humans differs significantly. A healthy resting human heart beats around 60 to 100 times per minute. But a cat’s heart races along at a much faster pace, typically around 140 to 220 beats per minute!

Heart Sounds

We often associate the human heart sound with “lub-dub,” but did you know a cat’s heart makes a different sound? A cat’s heart sound is often described as “lub-dub-dub,” with the extra beat being a normal part of feline physiology, resulting from the rapid closing of the heart valves.

Disease Prevalence

While both cats and humans can suffer from various heart diseases, the common types for each species differ. Humans often suffer from atherosclerosis, where fat gets deposited in the arteries, increasing the risk of heart attacks. Cats are rarely affected by this. However, they commonly suffer from a condition called hypertrophic cardiomyopathy, where their heart walls thicken. This condition is comparatively less common in humans.

What are some interesting facts about cat’s hearts?

Cats are fascinating creatures, and even their hearts have some unique characteristics. Here are some interesting facts about cats’ hearts:

  1. Heart Rate: The average resting heart rate of a cat is around 120 to 140 beats per minute. This is significantly faster than the average human heart rate.
  2. Heart Size: In proportion to their body size, a cat’s heart is relatively larger than that of a human. This is because cats are natural hunters and need extra cardiac output to support their active lifestyle.
  3. Cardiac Output: Cats have an impressive cardiac output, which refers to the amount of blood their heart pumps in a minute. It is estimated that a cat’s cardiac output is about 65-80 milliliters per kilogram of body weight per minute, while humans typically have a cardiac output of 55-75 ml/kg/min.
  4. Heart Murmurs: Cats, like humans, can also experience heart murmurs. These are abnormal sounds during the heartbeat cycle and can indicate various heart conditions. Heart murmurs in cats might be a sign of underlying heart disease.
  5. Heart Diseases: One common heart condition in cats is hypertrophic cardiomyopathy (HCM), where the walls of the heart become thickened. It’s the most common heart disease in cats and can affect cats of any age or breed.
  6. Heartworm Disease: Cats can also be affected by heartworm disease, which is caused by parasitic worms that live in the pulmonary arteries and heart. Though more common in dogs, it can be a serious health issue for cats as well.
  7. Heart Shape in Cats: While it’s more of a fun fact than a physiological one, some people believe that a cat’s nose leather (the surface of the nose) is unique and can form a shape resembling a heart.
  8. Adaptations for Hunting: The efficiency of a cat’s cardiovascular system is adapted for short bursts of intense activity, aligning with their hunting nature. Their heart is well-suited for the rapid energy bursts required during stalking and chasing prey.
  9. Stress and Heart Health: Cats are known to be sensitive creatures, and stress can impact their heart health. Stress-related cardiomyopathy is a condition that can affect cats, and it highlights the connection between their emotional well-being and cardiovascular health.
  10. Heart Sounds: Veterinarians use a stethoscope to listen to a cat’s heart sounds. The normal “lub-dub” sound of a healthy heart is essential for diagnosing any irregularities.


How Long Can A Cat Live With A Hole In Its Heart?

It depends on the size and shape of the hole in your cat’s heart, as well as how much damage it has done to the surrounding tissue. If it’s a small hole, then your cat might be able to live a normal life for years without any symptoms. But if it’s a large hole, that could mean that your cat will have to be put down fairly quickly.

Final Thoughts

It would be difficult to say exactly how big a cat’s heart is, since there are numerous factors affecting its size. Cats’ anatomy, their physical health, and even their emotions will come into play. For example, a cat witnessing the death of another pet cat may experience feelings of depression, which would affect its cardiovascular health. On the other hand, a playful feline may have somewhat larger heart muscles to accommodate for its more intense activity level.

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