How A Cat's Heart Works

A cat's heart has four chambers. The two upper chambers are called the right and left aorta, and the lower chambers are known as the right and left ventricles. A cat's heart works as follows:

  • Veins carry low oxygenated blood from the body to the right atrium.
  • Blood is stored in the right atrium momentarily until being pumped into the right ventricle.
  • The right ventricle pumps the blood into the lungs, where it is infused with fresh oxygen.
  • The blood then flows from the lungs back into the heart and is stored in the left atrium.
  • The blood is then pumped into the left ventricle.
  • The ventricle then pumps the freshly oxygenated blood to all other organs and body parts.
  • Once the blood is circulated, the veins carry the blood back toward the heart to begin the process again.

What Is Cardiomyopathy?

 Cardiomyopathy is a disease of the heart muscle. The three main forms of cardiomyopathy are Hypertrophic, Dilated, and Restrictive.

  • Dilated Cardiomyopathy (DCM) results in thinning of the heart muscle, heart enlargement, and the heart muscle cannot contract effectively.
  • Hypertrophic Cardiomyopathy (HCM) results in a thickening of the muscle wall of the heart. It is the most common form of cardiomyopathy in cats.
  • Restrictive Cardiomyopathy (RCM) is a fibrosis of the muscle of the heart making it stiff and inelastic, thereby not allowing the chambers to fill normally.

Although there are many types of potential heart problems in cats, Hypertrophic Cardiomyopathy is by far the most common heart condition affecting the feline population.

What Causes Heart Disease In Cats?

Heart disease in cats can be either congenital or acquired:

  • Congenital heart disease in cats is present at birth and can be inherited from the parents.
  • Acquired, or adult-onset heart disease in cats often occurs in middle-aged to older animals due to wear and tear on the heart structures, but can also result from an injury or infection.

While cardiomyopathy is the most common form of acquired, adult-onset heart problems in cats, the two most common types of congenital heart disease in cats are:

Sings of Heart Disease In Cats

There are several possible signs of heart disease in cats that cat owners can be on the lookout for, including:

  • Lethargy/weakness/inactivity
  • Difficulty with or discontinuing exercise
  • Shortness of breath or difficulty breathing possibly accompanied by fluid buildup in the lungs and chest
  • Sudden paralysis of the hindquarters
  • Fast breathing 
  • Open-mouthed breathing
  • Fainting/collapse
  • Chronic coughing
  • Regularly elevated heart rate

The above-mentioned signs can indicate one of many possible conditions, including feline heart disease and potentially something unrelated to the cardiovascular system. If you notice any of the above signs, we recommend scheduling an appointment.

Diagnosis Of Hypertrophic Cardiomyopathy In Cats

Diagnosing hypertrophic cardiomyopathy in cats begins with one of the most effective diagnostic tools for detecting heart disease in cats: a cardiac examination. A cardiac examination allows us to follow a thorough investigative protocol to determine the presence and extent of hypertrophic cardiomyopathy in cats. A cardiac examination can include some or all of the following procedures:

  • Physical exam: We listen to your cat's heart and lungs with a stethoscope to check for abnormal sounds.
  • Ultrasound: We can view and measure your cat's heart's chamber, valves, and muscles as well as the major cardiac vessels using sound waves and without any pain or invasion.
  • Blood pressure: We perform a standard, non-invasive blood pressure test to monitor systolic and diastolic pressure.
  • Electrocardiogram (EKG): We measure the electrical activity of your cat's heart to diagnose arrhythmias and other heart conditions.
  • X-Rays: We can view the heart's overall size, its positioning in the chest, and the general condition of the lungs.
  • Blood analysis: We can perform a complete blood work chemistry to help assess the general health of your cat.

A blood chemistry analysis can also determine the level of thyroid hormone present in the bloodstream. This is very helpful when evaluating hypertrophic cardiomyopathy in cats, as an overactive thyroid gland can be an underlying cause of heart disease.

Treatment Of HCM

Presently, there is no cure for hypertrophic cardiomyopathy in cats, although it can be treated to slow down the progression of the disease. Changes to the size and structure of the heart muscle are irreversible so diagnosing and treating the disease can help your cat live a longer and healthier life. In some cases in which the heart disease is secondary to a treatable condition such as hyperthyroidism, the signs may improve when the underlying condition is corrected.

Once a diagnosis of cardiomyopathy has been made, we may prescribe medications to slow down the progression of the disease, or to treat the clinical signs.  These medications may decrease workload on the heart, relax the heart muscle, slow down the heart rate, help the heart muscle contract, or relieve fluid buildup in the lung tissue.

Complications Associated With HCM

Many felines diagnosed with HCM eventually develop signs of congestive heart failure. Cats with HCM are at risk for developing blood clots that can escape the heart and eventually become lodged in a blood vessel that has become too narrow. This is called a thromboembolism. A common area for this to occur is the hindquarters region, a point where the aorta splits before going into each rear leg. If this happens, paralysis and severe pain will result. In fact, paralysis and pain are very common reasons that many owners initially bring their cats to see a veterinarian. However, what they thought might be a broken leg or lameness is actually hypertrophic cardiomyopathy in cats.

Prognosis For Cats With Cardiomyopathy

Even though hypertrophic cardiomyopathy in cats is incurable, the old saying, an ounce of prevention equals a pound of cure, still greatly applies to cats with heart disease. If HCM is detected and arrested in its mild to moderate stages, then the prognosis for an essentially normal life for a number of years can be good. However, the form and severity of the disease at the time of discovery will ultimately dictate the prognosis. 

HCM can worsen quickly or progress slowly over a period of years.

  • HCM can remain undetected in some cats until the advanced stages, and the time between diagnosis and death can be a matter of weeks or months.
  • HCM can remain mild in some cats and never progress to the advanced stages.
  • HCM can progress to the advanced stages despite medical intervention.

The existence of these variables and possibilities makes both preventive and follow-up care of the utmost importance where heart disease and congestive heart failure are concerned.

Scheduling Cardiology Tests For Your Cat

If you suspect that your feline friend might be at risk for, or suffering from, any heart conditions, please contact us immediately to schedule an appointment today.