Restrictive Cardiomyopathy in Cats

Cardiomyopathy is a term used to generally describe any dysfunction of the heart that cannot be linked to another underlying cause such as a specific disease or injury. The literal translation of the term is “disease of the heart muscle.” There are three types of cardiomyopathy: hypertrophic, dilated, and restrictive. Each of these conditions is incredibly serious and can be life-threatening to your cat. If you suspect your cat is suffering from any heart-related disease or defect you should seek immediate veterinary care as the speed of treatment could potentially make a significant difference in your cat’s lifespan and quality of life.

Restrictive cardiomyopathy will typically occur gradually and symptoms will worsen over time. Initially, you may notice no signs your cat is suffering from the condition, or the symptoms will be so minor or sporadic that they will be easily missed. Signs to watch for that may indicate your cat may be suffering from restrictive cardiomyopathy include:

• Panting or open mouth breathing
• Exercise intolerance
• Lethargy
• Rapid breathing
• Decreased appetite
• Enlarged stomach

Restrictive cardiomyopathy refers to a condition in which your cat’s heart muscle becomes damaged through stiffening of the muscles. When this occurs, your cat’s heart cannot properly expand to fill with the necessary amount of blood to supply to the rest of the body’s organs. The lack of ability to expand usually occurs as a result of buildup of scar tissue on the inner lining and muscles that make up the ventricles of the heart.

The exact cause of restrictive cardiomyopathy is unknown, however there are several suspected culprits. Veterinarians have found a connection between restrictive cardiomyopathy and cats fed a commercial diet without sufficient amounts of taurine. Cats with hyperthyroidism also have a higher rate of incidence of the condition. Increased blood pressure in general, or a heart attack, can both cause restrictive cardiomyopathy through the creation of scar tissue. Finally, it is suspected that cats with parasites such as heartworms also have a higher risk of developing restrictive cardiomyopathy.

Diagnosis of restrictive cardiomyopathy in your cat will begin with a thorough physical exam by your veterinarian. During this initial visit, you should supply your vet a complete list of symptoms including any worsening or improvement, the approximate time of onset, and whether they are consistent or intermittent. You should also let your vet know if your cat is currently suffering from thyroid disease or may have been involved in a serious injury or has suffered a known heart attack.

Your vet will attempt to rule out other conditions during your visit. They may take blood and urine samples to be sent out for a complete blood panel which will help identify any infection or excess proteins in the blood or urine. They will also listen to your cat’s heart carefully to determine whether it is making the appropriate sounds and is functioning with a regular beat.

Next, your vet will carefully examine the workings of the heart through various tests and imaging. An electrocardiogram measures the electric conductivity of your cat’s heart. This test is non-invasive but may require your cat to be shaved in areas. This is due to the fact that small monitors must be affixed to your cat and be in contact with the skin with good conductivity. Long, dense fur will often prevent accurate signals. Your cat can be awake for this procedure and must remain calm and quiet while standing or laying on their side. Your vet may also order an ultrasound and x-ray of the heart and chest cavity. These images will allow your vet to identify the presence of scar tissue or any other defect of the heart. These three tests together are the definitive diagnostic tools to properly identify restrictive cardiomyopathy.

Restrictive cardiomyopathy in your cat is treated in several stages. First, if the cause is an underlying condition such as thyroid disease or parasite infection, your vet will prescribe appropriate medicines to correct these illnesses.

Once the underlying condition has been managed, your vet may prescribe several different types of drugs that will need to be administered long term. These include ACE inhibitors which help improve heart function and diuretics which help remove excess fluids. Your vet may also prescribe a special diet that is low in sodium or high in other essential nutrients that help support your cat’s heart function. 

If your cat is suffering from restrictive cardiomyopathy, treatment and management will have to continue over the course of its life. The heart is not generally able to regenerate or heal after suffering from damage. Additionally, the condition will most likely worsen over the course of time. With appropriate medicines and management you can prolong the life of your cat and eliminate symptoms, but there is no cure for this condition.