Enlarged Heart (Dilated Cardiomyopathy) in Cats

Cats with the symptoms of DCM are usually well into the progression of the disease, and often have heart failure by the time of diagnosis.

Cats who are having difficulty breathing require immediate veterinary attention.

DCM typically affects the left ventricle (the bottom left chamber of the heart). In some cases, the right ventricle (the bottom right chamber of the heart) also loses heart muscle and does not function properly. In these cases, fluid accumulates in the abdomen and chest as well as the lungs, which often appears of swelling in the abdomen.

Cats with DCM are predisposed to saddle thrombosis (a clot in the circulatory system that cuts off the blood to the hind limbs).

In the past, there was a significantly higher incidence of taurine-related DCM. Since the link between taurine deficiency and DCM was discovered in the 1980s, all cat food manufacturers have added taurine to their food. Cats who do not eat commercially produced cat food are at risk of taurine-related DCM.

Feline dilated cardiomyopathy is uncommon, now that most cat foods contain adequate taurine levels. Cases of taurine-related dilated cardiomyopathy (DCM) can occur in cats who are not fed commercial cat food, including vegan, vegetarian, or homemade food. Non-taurine-related DCM occurs more often in middle aged and older cats.

Certain breeds are more susceptible to DCM, including:

• Siamese
• Burmese
• Abyssinian

Dilated cardiomyopathy occurs when the heart muscle in the lower half of the heart deteriorates, which weakens its pumping capability. The cause of this is either taurine deficiency or idiopathic (having an unknown cause).

As the heart muscle deteriorates, the ability of the heart to deliver blood to the tissues declines. Initially, the kidneys are able to compensate for poor blood flow from the heart. Eventually the heart muscle becomes so weak the other systems are unable to compensate appropriately. At this stage, the patient enters heart failure, leading to symptoms of DCM.

The symptoms of DCM in cats are variable and often hard to recognize.

Diagnostic tools to identify DCM include:

• Physical examination
• Bloodwork
• Imaging such as X-rays and ultrasound
• ECG (electrocardiogram)
• Taurine level testing
• Sampling of fluid from the chest cavity

There is no cure for non-taurine related DCM. Treatment aims to reduce the symptoms and improve heart function. Strategies include:

• Diuretics to increase fluid excretion, reducing the heart’s workload
• Medications to increase heart strength
• Antiarrhythmics to correct the heart beat
• Blood thinners to prevent aortic thromboembolism
• Appetite stimulants

Cats with DCM are typically in heart failure by the time they are diagnosed. In these cases, supportive care is required in addition to specific treatment. Supportive therapies include:

• Oxygen therapy
• Thoracocentesis (draining the fluid from the chest cavity)
• Gentle warming of the body

Repeat examinations are required to monitor response to therapy. Repeat thoracentesis is also often needed.

In cases where taurine levels are low, treatment includes administering taurine supplements. Taurine supplementation takes two to four months to resolve symptoms.

Cats with taurine-related DCM typically have a good prognosis if they survive the first few weeks post-diagnosis. Taurine supplementation for 2 to 4 months is necessary for full recovery. Long-term, these cats require an appropriate, nutritionally balanced diet.

The prognosis for cats with non-taurine related DCM is grave, with survival times of weeks to months.

Prevention of taurine-related DCM requires appropriate taurine levels in the diet. Providing any high-quality commercial cat food is sufficient.

There are no proven preventative measures for non-taurine related DCM since the cause is not known.

DCM is uncommon in cats.

• Taurine supplementation
• Drugs to support heart function
• Supportive care