One of the most prevalent and potentially serious heart conditions affecting cats is cardiomyopathy. This term encompasses a group of diseases that affect the heart muscle, impairing its ability to pump blood effectively. Understanding this condition is crucial for cat owners, as early detection and proper management can significantly improve the quality and length of their feline friend's life.
Cardiomyopathy in your cat
Cardiomyopathy is a disease affecting the heart muscle. There are several main forms of the disease :
- hypertrophic cardiomyopathy (HCM)
- restrictive cardiomyopathy (RCM)
- arrhythmogenic right ventricular cardiomyopathy (ARVC)
- dilated cardiomyopathy (DCM).
HCM is the most common form encountered in cats, with the other forms being far less common. HCM is often identified in middle-aged cats and is more common in male cats than females. Cardiomyopathy can be associated with signs of heart failure and abnormal heart rhythms.
How does the heart work?
Similar to the human heart, the cat's heart is a muscular pump with four distinct chambers. Blood is sent from the right side of the heart to the lungs, where it absorbs oxygen. Blood is pumped throughout the body by the left side once it is taken from the lungs.
What is cardiomyopathy?
Cardiomyopathy literally means disease of the heart muscle (cardio = heart and myopathy = muscle disease). There are four forms of the disease (although lots of variations of these are also recognised).
The most common form of cardiomyopathy is hypertrophic cardiomyopathy, in which the heart muscle becomes abnormally thick which prevents the heart from working properly and reduces the amount of blood flowing through it. Arrhythmogenic right ventricular cardiomyopathy affects the right side of the heart causing it to become dilated along with identification of abnormal heart rhythms. Restrictive cardiomyopathy usually affects the left side of the heart, but can affect both sides causing abnormal heart muscle relaxation. Another form of cardiomyopathy is dilated cardiomyopathy that is caused by stretching of the heart muscle. This is often seen in cats whose diet contains insufficient amounts of a chemical called taurine. However, DCM is much less common now because pet food manufacturers add extra taurine to their cat foods.
What causes hypertrophic cardiomyopathy?
The exact cause of cardiomyopathy in cats is not always clear, but genetics seem to play a significant role, especially in breeds such as American shorthair,Maine Coons, Ragdolls, and Persians. Other factors such as high blood pressure, thyroid disorders, kidney disease and certain infections can also contribute to the development of this condition.
If there is an underlying cause the condition is called secondary HCM. However, HCM can also occur in otherwise healthy cats and where there is no apparent cause and this is termed idiopathic or primary HCM.
Aging cats are generally more prone to cardiomyopathy, emphasizing the importance of regular veterinary check-ups for senior feline companions.
Any muscle that has to exert more energy grows larger and the muscle of the heart is no different. We refer to this growth as hypertrophy. The heart muscle has to work harder in some cats with very common illnesses.
As the heart muscle becomes thicker the chambers within the heart get smaller and so can hold a smaller volume of blood. Although the heart contracts quite strongly it can only pump a small volume of blood into the circulation. The thickened heart muscle cannot relax properly and so between contractions the chambers do not expand and fill with blood.
Although HCM often affects the entire heart, occasionally only a portion of the wall is damaged more severely than the others. The thicker heart muscle needs a lot of energy and oxygen, but it frequently has inadequate blood flow. A little scar may occur if certain cells in the heart muscle die from oxygen starvation. An irregular heartbeat and discomfort could result from this scar.
What causes dilated cardiomyopathy?
This illness causes the heart to inflate (like a balloon filled with water) by stretching the cardiac muscle. Research revealed that taurine dietary deficiencies were a common cause of DCM in cats, which was once again a common occurrence. The only necessary amino acid that can be found in beef protein is taurine. With the addition of taurine to cat food following this discovery, the illness has all but vanished in felines. When dilated cardiomyopathy occurs, the heart muscle's contractions weaken and the body's ability to pump blood is compromised.
What causes other types of cardiomyopathy?
The cause of RCM and ARVC is unknown. There might exist an unidentified genetic component. We simply don't know if RCM is a continuation of the illness process that causes HCM. Treatment for these illnesses is typically the same as if the cat had HCM.
How would I know if my cat has heart disease?
It's possible that you won't become aware of your cat's cardiac issues until it's too late. Cats are typically adept at hiding health issues, so until the illness is rather severe, there might not be any symptoms. Heart disease can be indicated by a wide range of symptoms. Your cat may find it difficult to breathe if fluid accumulates in the chest or lungs as a result of heart failure. An irregular heartbeat or a build-up of fluid in the chest might result in collapse and a reluctance to exercise due to insufficient blood flow to the brain and muscles.
Frequently, an owner will observe early symptoms that don't seem to be connected to heart disease, such rapid breathing, blindness, or issues with the back legs.
Blood clots within the heart chambers might occur as a result of the irregular blood flow within the heart. These clots can fragment at any time and release pieces that enter the bloodstream (emboli). These emboli are transported via the bloodstream to smaller blood arteries, where they lodge and create an obstruction. This occurs frequently in the blood vessels that supply the back legs, which can result in paralysis, or in the brain, which can cause neurological indications. Hypertension, or elevated blood pressure, is linked to heart disease and increases the risk of blood vessel rupture. Your cat may become blind if the blood vessels in their eyes are impacted.
How will my vet know that my cat has cardiomyopathy?
A thorough examination of you cat will often be enough to tell your vet that your cat has heart disease. Your veterinarian may detect an irregular heart rhythm or alterations in the heart sounds, known as a "heart murmur," while using a stethoscope to listen. Other changes in your cat's look that could indicate the presence of cardiac disease could be noticed by your veterinarian. Usually, X-rays are required to determine whether the heart is enlarged or atypically shaped. The external look of the heart shadow may not alter significantly, though, because the majority of the muscle wall growth in HCM happens inside the heart. Additionally, blood samples may be obtained in order to do the NT-proBNP test, which can determine the likelihood of cardiac disease. There may also be secondary heart failure-related abnormalities, such as fluid in the abdomen or chest.
Ultrasound is the best method for diagnosing cardiomyopathy. Your veterinarian can evaluate the heart muscle using an ultrasound scan to see whether it is excessively thick or has strained. The electrical activity of the heart beats is recorded by an electrocardiogram (ECG), and in cardiomyopathy, the heart may beat abnormally or irregularly, which is seen on the ECG.
After a cardiomyopathy diagnosis, an investigation to look for underlying reasons should be conducted. It is recommended to measure your cat's blood pressure in order to detect hypertension if it has HCM and to conduct routine screening procedures. In cats that are middle-aged or older, thyroid hormone assays are particularly important for screening against hyperactive thyroid disease.
Can cardiomyopathy be treated?
Your cat might heal completely if your veterinarian finds an underlying source of the issue that can be addressed. HCM is common in cats with hyperactive thyroids, but if the thyroid condition is controlled, this will go away. Supplementing with taurine can sometimes help the heart muscle heal if your cat's DCM was caused by a taurine shortage (but there may be other causes as well). In these situations, your cat's heart condition will require treatment at first, but when the heart heals, the medication may be stopped. Unfortunately, most of the time no underlying ailment is found, or if it is, there is no cure. Long-term medicine and other interventions can delay the progression of heart disease if detected early enough, but they cannot totally reverse it.
As part of a long-term treatment plan, oral diuretics are given to lower lung fluid accumulation and exercise tolerance is maintained.Since the heart muscle's improper contraction is the primary issue with DCM, medications can be administered to strengthen the heart muscle's contractions. Medication can be administered to treat any irregular cardiac rhythms that may be present.
The best technique to keep cats with cardiomyopathy from getting blood clots and emboli is a topic of significant discussion. Most veterinarians administer clopidogrel once a day to all animals suffering from cardiomyopathy. Although clopidogrel lowers the chance of blood clots forming, therapy has little effect in dissolving existing clots. Cats typically require far smaller dosages of human drugs than one might anticipate because they do not tolerate them well. Unless your veterinarian specifically instructs you to do so, never give medication to your cat.
Patients undergoing treatment should have regular blood testing for kidney function as well as other conditions.
How long will my cat live?
If your cat has heart disease, it is difficult to estimate how long it will survive or how well its quality of life will be. Several factors depend on how far along the illness has come. While some cats with HCM will experience blood clots or heart failure, others will live a normal life despite their cardiac disease. After receiving a heart failure diagnosis, your cat's chances of survival are approximately 69 months on average, though they might range from a few weeks to several years. Certain animals suffering from heart failure pass away unexpectedly, most likely due to serious cardiac rhythm abnormalities or large emboli.
Cats with DCM likewise have a bad prognosis; the majority only live for a few months.
In conclusion, feline cardiomyopathy is a serious and relatively common heart condition that affects our beloved cats. Being aware of the risk factors, recognizing the symptoms, and seeking prompt veterinary care can make a significant difference in managing this condition. With proper attention, love, and care, cats with cardiomyopathy can lead happy and fulfilling lives, bringing joy to their owners for years to come.
