Heart disease is the leading cause of sudden death in cats. It affects cats of every age and breed. A study found that when they tested 103 seemingly healthy domestic (privately owned) cats, 16 were found to have heart disease.
How A Healthy Heart Functions
A healthy cat’s heart has 4 distinct sections, 2 upper (right and left atriums) and 2 lower (right and left ventricles). These sections contract and relax in a specific order for the blood to be pumped through the heart. When a section relaxes (called systole), that section fills with blood. As a section contracts (called diastole) the blood in that section is moved onto the next part of it’s journey. Valves are in between these sections making sure that blood continues flowing in the proper direction.
The left ventricle is affected by most cases of heart disease in cats. The job of the left ventricle is to take in newly oxygenated blood from the lungs and pump it back out to the rest of the body.
Types of Heart Disease in Cats
Heart disease in cats is not just one disease, but rather a whole collection of diseases that affect the functioning of the heart. Cardiomyopathy is a term regarding any heart disease in cats affecting the heart muscle itself. Cardiomyopathy accounts for 2/3 of all heart conditions in cats. It is almost always acquired over time (as opposed to the cat having been born with it).
Hypertrophic Cardiomyopathy (HCM)
HCM is the most common heart disease in cats by far. Approxomitly 80- 90% of cardiomyopathy cases seen at Ohio State University Veterinary Hospital are HCM. Cats aged 5 -7 years old are the most likely to suffer from HCM , but it has been seen in cats as young as 3 months and as old as 17 years.
HCM is characterized by the thickening of the muscle tissue of the left ventricle of the heart. When this tissue thickens, it is no longer able to stretch and relax the way that it should. This means that the left ventricle has a difficult time filling up with blood. The result is that not enough blood is being pumped back out of the heart into the body.
Since blood is not moving into the left ventricle as quickly as it is being moved through other parts of the heart, there can be a back of blood in the pulmonary veins and lungs. Fluid building up on the lungs causes difficulties with breathing and ultimately congestive heart failure. As a cautionary note – cats do not develop a cough when suffering from suffering from congestive heart failure like dogs and humans do. They may however breathe through an open mouth or pant.
Feline Aortic Thromboembolism (FATE) is another potential complication of HCM. Sometimes a blood clot (called a thrombus) will develop and attach to the wall of the heart. If this thrombus breaks loose and ends up in the blood stream it is now called a embolus. These emboli can block blood from flowing into smaller arteries. Most of the time in cats, these emboli will lodge in the arteries that feed the hind legs, which can cause severe pain, weakness, and paralysis of one or both of the hind legs.
Restrictive Cardiomyopathy (RCM)
RCM is the second most common type of cardiomyopathy (about 10% of cases). It is most often seen in older cats. This is characterized by excessive scar tissue build up on the inner lining of the left ventricle. The heart wall becomes stiff making it difficult to relax or constrict properly and so the blood does not fill or empty as it should.
Dialated Cardiomyopathy (DCM)
Compared to HCM and RCM, DCM is fairly rare (only 1- 2% of cardiomyopathy cases). DCM is characterized by a thinning of the muscular wall of the left ventricle. This thinning causes the left ventricle to be enlarged and the muscle to be weaker and have more difficulty contracting. The result is a reduced blood flow coming out of the heart.
Symptoms of Heart Disease in Cats
Often in the early stages of heart disease cats will be asymptomatic. Some cats never develop clinical symptoms. Symptoms tend to suddenly appear at a critical point in the progression of the disease and the cat’s condition may deteriorate rapidly. If you think that your cat may be suffering from heart disease, make an appointment with your veterinarian right away.
Symptoms of heart disease in cats can include:
- Difficulty breathing
- Inability to walk/paralysis of the hind legs
- Loss of appetite
- Weak pulse
- Abnormal heart sounds (such as a heart murmur)
- Bluish color in the foot pads and/or nail beds
Causes of Heart Disease in Cats
Heart disease in cats affects cats of every age and breed. For the most part no one really knows what causes it. Potential underlying causes of heart disease in cats include: hypertension, hyperthyroidism, exposure to toxins, taurine deficiency, excessive growth hormones (Acromegaly), lymphoma, and genetic defects. Holistic veterinarian, Dr. Karen Becker, DVM thinks that there are nutritional reasons for the occurrence of heart disease in cats as foods can affect the way genes are expressed. There are also a few breeds of cat that seem to have a predisposition towards developing heart disease: Maine Coons, Ragdolls, American Shorthairs, and Persians. However, mixed breed cats seem to have the most cases of heart disease.
Diagnosis and Treatment
The first thing your veterinarian will have to do is rule out any other conditions that may cause similar symptoms. Hypertension and hyperthyroidism can mimic the symptoms of HCM. Your veterinarian will likely do x-rays and electrocardiograms (EKGs) for information about how the heart is functioning, but the real definitive diagnosis will come from an ultrasound of your cat’s heart. A blood test called NTproBNP is also available to aid in diagnosis.
As of the time this is written, there is no cure for heart disease in cat. Cats that are diagnosed with heart disease may need to be hospitalized (especially if congestive heart failure is present). The prognosis for a cat suffering from heart disease is highly dependant on the stage of the heart disease when it is diagnosed. A number of different medications may be prescribed such as:
- Slows the heart rate
- Corrects the irregular heart beat
- Controls the blockage of blood flow
- ACE inhibitors
- Treats congestive heart failure
- Improves blood flow through the left ventricle
- Slows the heart rate
- Treats the irregular heart beat
- Reduces the enlargement of the left ventricle
- Reduces blood clots
- Prevents blood clots
- Diuretic (removes excess fluid from the body)
- Nitroglycerin ointment
- Improves blood flow by dilating the left ventricle and the arteries.
- Diuretic for congestive heart failure
Holistic veterinarians may also suggest using these natural treatments:
- Heart glandulars and herbs (like Hawthorn)
- Amino acids (taurine, L-arginine, acetyl L-carnitine, etc)
The Good News
Treatment for heart disease in cats is quite good – especially if it is found early. Symptoms can be very well controlled. Cats can live several years with a good quality of life while being treated for heart disease. There is a lot of research being sponsored by organizations like the Winn Feline Foundation to find out more about the causes, find ways to detect it earlier, improve treatments, and of course working for a cure. Yearly visits to the veterinarian are highly recommended so that preventative tests can be done. Education about heart disease and early detection can save lives.