Cat Heart Disease

Cats, as most people know, are extremely stoic animals. It is very rare that a cat will complain about pain or discomfort. This may seem like a desirable trait to some, but in fact, it makes it much more difficult to determine whether or not the cat needs medical attention. Luckily, our feline companions do not seem to be prone to the myriad of diseases that dogs seem to be. However, they can acquire their fair share of medical problems. For example, one of the more common heart diseases in cats is known as feline hypertrophic cardiomyopathy (FHCM), a serious and progressive disease of the heart muscle.

The heart is a phenomenal organ and is quite possibly the most important organ in the body. It acts as a central pump, moving oxygen and nutrient-carrying blood from the lungs to the rest of the body.

The blood moves around the body in a circuit that is controlled by the pumping of the heart, making some vital stops along the way. The heart has four basic chambers, the right and left atrium, and the right and left ventricle. When the muscles in the right and left atrium are contracting, they push the blood into their respective ventricles. The ventricles have thick muscular walls, as they are responsible for pumping blood to distant areas of the body. When the muscles of the right ventricle contract, the blood in the chamber is pushed to the lungs, where the oxygen is taken up by the red blood cells. This blood then returns to the left atrium and subsequently the left ventricle, where another contraction pushes the blood to the rest of the body. Other organs, such as the brain, kidney, stomach, and liver, receive this oxygen-containing blood. This circuit is continuous as long as the heart keeps pumping.

Heart disease is divided into two categories: congenital (diseases that are present at birth) and acquired (diseases that develop later in life). When something goes wrong with the heart, there are a number of things that can be the source of the problem. Valves in the heart, which regulate blood flow between the chambers, can be leaky or unable to open wide enough. There can be holes present in the muscle walls between the chambers or between the major vessels. The muscle walls can become damaged or changed for several reasons. Any of these can cause changes to the amount of blood that is circulating around the body, and if severe enough, the disease will present itself in some characteristic symptoms, such as trouble breathing and fainting.

In cats, feline hypertrophic cardiomyopathy is a disease of the heart muscle. There is no definitive cause for this disease, but it is known to often be associated with high blood pressure or hyperthyroidism. In the case of FHCM, the muscle of the left ventricle becomes thickened and stiff so that it cannot be easily fill with blood. The condition can be compared to a balloon – a fresh new balloon fills easily with air as it stretches, while an old and stiff balloon does not fill as well, because it does not stretch. If the left ventricle of the heart has trouble filling with blood, there is less volume of blood in the chamber before the next contraction, and as a result, less blood is pumped around the body with each heart beat. When there is not enough oxygen-rich blood reaching the brain, episodes of fainting can occur. In addition, if blood is not being pumped out to the body and starts backing up in the heart, the increased pressure causes fluid to leak into the lungs making it difficult for the cat to breath.

FHCM is a condition that affects mainly middle aged cats, although younger cats can also be affected. It is much more common in males than females, and seems to be more prevalent in Persians and Maine Coons.

Symptoms

Symptoms of this disease include loss of appetite, lethargy or weakness, sudden development of difficulty breathing or fainting. It should be noted, however, that symptoms are not always present and the first sign of disease could be sudden death. Another consequence of the disease may be the formation of a blood clot that lodges in a blood vessel near the hind limbs, resulting in paralysis and loss of blood supply to the hind limbs. It is therefore important to bring your cat to your veterinarian every year for a thorough physical examination. Your veterinarian will check for heart murmurs and changes in heart rhythms that can suggest heart disease.

Diagnosis

FHCM is diagnosed with some very specific tests that may require referral to a cardiologist. Your veterinarian will first perform a thorough physical exam and will check the heart for murmurs and abnormal rhythms, as well as examine the entire body for other abnormalities. The blood will be tested for signs of other diseases that can be affecting the heart. X-rays of the chest will be taken to see if any of the heart chambers appear enlarged, and to determine whether or not the lungs are clear. An electrocardiogram (ECG) is a recording of the electrical activity of the heart and will tell your veterinarian about the abnormalities in the heart rhythm, and changes in the size of the chambers. Finally, an ultrasound of the heart can be performed by a cardiologist to visualize abnormalities and the ability of the heart to pump effectively.

Treatment

Before a treatment protocol is developed for your cat, thorough bloodwork must be performed to rule out other diseases that may be present, such as kidney failure. The functional ability of other organs is important in determining the medications that will be prescribed and the management of the heart disease.

The goal of treating FHCM, as it is a progressive disease (meaning that it gets worse over time), is to treat the symptoms and try to prevent the disease from progressing. The treatment protocol depends on the severity of the disease and the symptoms that the cat is experiencing. For example, if your cat is having difficulty breathing there are medications that help reduce the fluid load in the lungs to make breathing easier. Medications may also be prescribed to help the heart function better, by slowing down the heart rate and improve the muscle relaxation in the ventricle. A medication, such as aspirin, may also be recommended to prevent clots from forming if your cat is at risk. administration of this, however, must only be done following the instructions of your veterinarian.

Prognosis

Cats that are not showing symptoms of disease may live for years without problems. The longevity and quality of life for symptomatic cats, however, depends on the stage of the disease. Unfortunately, those with heart failure may live approximately one year or less. It is important to remember that, ultimately, it is the quality and not the quantity of life that counts.

Heart disease in cats – additional information

By Beverly Wong – Pets.ca writer