Enlarged Heart in Cats

Your veterinarian may use the term dilated cardiomyopathy (DCM) to describe the condition of enlarged heart, specifically the loss or weakening of cardiac muscle, leading to decreased function and possibly to congestive heart failure.

An enlarged heart is a condition in cats in which the muscle of the heart increases in size due to many different possible causes. This increase causes the heart to work harder to pump the same amount of blood, resulting in decreased efficiency and possibly heart failure. Though it used to be more common, a link between taurine deficiency and enlarged heart has been established, leading cat food companies to include taurine in their food, and a subsequent significant drop-off of enlarged hearts in cats. It's worth noting that outdoor cats or those fed diets not based on commercial cat food may still be at risk for taurine deficiency.

Cats with enlarged hearts will often have a broad range of symptoms, and depending on the age of the cat, these could be mistaken for simply a sign of being elderly. Only veterinary examination can pinpoint dilated cardiomyopathy for certain. The primary symptoms include:

• Listlessness (depression)
• Lack of appetite
• Weakness/sluggishness
• Partial paralysis as blood clots become more common
• Abnormal heart rhythm
• Difficulty breathing, possibly with a cough

It is widely believed now that taurine deficiency was the primary cause of enlarged hearts in cats, but with the addition of taurine to cat food, this has been largely resolved. Modern cases have no single cause that can be pinpointed, but instead there are several possible known culprits, including:

• Parasites
• Viruses
• Genetic predisposition to enlarged heart

Assuming taurine deficiency is not the cause of your cat's enlarged heart, a more in-depth examination will be needed.

Your veterinarian will need to examine your cat, particularly the sounds of the heart and the ability of your cat to breathe on their own. 

If your cat suddenly stops eating, shows signs of general disinterest or extreme fatigue, has difficulty breathing, or behaves in a way that indicates partial paralysis or pain in one specific region, it is a good idea to have them examined as soon as possible. 

On examination, a veterinarian will be listening for a galloping heartbeat, a heart murmur, weak pulse and other abnormal heart rhythms. In addition, the cat's breathing will potentially be labored as fluid builds up around the heart and lungs, a condition called effusion. Further examination through blood drawing can indicate heart damage by evaluating levels of creatinine, a chemical marker of muscle breakdown, an increase of which can suggest cardiac damage. Ultimately, an echocardiogram is the best test for diagnosing enlarged heart, and will be the next procedure if the initial examination suggests cardiac enlargement.

Your vet may ask you about your cat's eating habits lately compared to normal. In addition, they will likely ask about onset of a cough, decreased energy and playfulness, if they have lost interest in toys or novelties that used to get their attention. Being clear about your cat's normal behavior versus what they have experienced since you've noticed the change can be essential in helping your veterinarian determine what they need to evaluate. 

Treatment for cats with enlarged hearts involves reducing swelling of the heart as well as reducing the amount of fluid accumulating in the chest. This will improve breathing and allow the doctor more time to establish a cause. If it is determined that taurine deficiency is the underlying cause of the DCM, taurine will be administered, but even in these cases, the prognosis is not good. Once cats begin to exhibit symptoms of enlarged heart, it can be too late to treat effectively. Unless your cat is not eating prepared cat food, lack of taurine is not the primary cause, so identifying the culprit takes precious time. For the most part, treatment is focused on improving heart function while a cause can be established.

Diuretics

Diuretics work by helping your cat expel excess fluids that their body might be retaining. Diuretics are usually administered orally, but depending on the condition of your pet, may be given intravenously. There is little risk here but they do not offer a permanent solution.

Antiarrhythmic Drugs

AADs work by inhibiting the impulses that cause irregular heartbeats. They are not useful if the enlarged heart has progressed to congestive heart failure, though.

Administered Oxygen

This is another stopgap, designed to give your cat's doctor more time to find an underlying cause. 

If caught quickly enough, the prognosis can be about 50% for survival in cats with enlarged hearts, assuming taurine deficiency is the cause. For examples without a readily apparent trigger, expected recovery rates are very low. Even for those with taurine problems, the chance at survival is not high. Long-term management of the condition depends on the initial trigger, but once a cat has survived and the condition causing the enlarged heart is identified, it can be addressed accordingly.