Common Causes & Symptoms of Cardiomyopathies in Dogs & Cats

Cardiomyopathies are diseases of the heart muscle, and they can affect dogs, cats, humans, and a multitude of other species. There are different types and causes of cardiomyopathies, which is why it’s important for pet parents to work with a family veterinarian or board-certified veterinary cardiologist to determine a diagnosis and treatment plan. If you have concerns about your pet’s heart health, here is information regarding common causes and symptoms of cardiomyopathies in dogs and cats.

WHAT ARE THE MOST COMMON TYPES OF CARDIOMYOPATHIES IN DOGS & CATS? 

The most common type of cardiomyopathy in dogs is dilated cardiomyopathy (DCM). In this disorder, the heart muscle becomes weakened, thin, and does not pump efficiently – leading to enlargement of the cardiac chambers. DCM is the second most common acquired heart disease in dogs.  

In cats, hypertrophic cardiomyopathy (HCM) is both the most frequently-seen cardiomyopathy and the most common acquired heart disease overall.  Cats with HCM have hearts with a thickened muscle that does not relax well during diastole, the phase of the cardiac cycle in which the chambers fill with blood.  

WHAT CAUSES CARDIOMYOPATHIES?  

Typically, genetics are to blame, but rarely, there are nutritional, viral, hormonal, parasitic, or bacterial causes of heart muscle disease in pets.  In cats, high blood pressure and high thyroid levels can cause the heart muscle to thicken. 

WHAT ARE SOME SYMPTOMS OF CARDIOMYOPATHIES IN PETS? 

Regardless of the type of heart disease, all cardiomyopathies may lead to congestive heart failure and a build-up of fluid within the lungs and/or abdomen. Signs that a pet owner might notice include:  

• Difficulty breathing 
• Coughing 
• Exercise intolerance 
• Fainting, especially with excitement or exercise   

It is important to note that seeing one of these signs does not necessarily mean that there is a problem with your pet’s heart, but it is a good idea to mention your observations to your family veterinarian to see if further diagnostics are warranted.  Physical exam findings that your family veterinarian might detect include:  

• The presence of a heart murmur 
• Arrhythmia (irregular heart beat) 
• Poor pulse quality 
• Pale gums 
• A rapid heart beat
• Labored breathing with “crackles” (soft popping sounds) when listening to the lungs with a stethoscope.   

WHAT CAN PET PARENTS DO TO ENSURE THEIR PET’S HEART REMAINS HEALTHY?  

Here are a few tips:

• Feed your pet a high-quality diet that DOES NOT have high levels of potatoes or legumes (such as lentils, beans, and peas). Some diets with these foods as the top five ingredients have led to dilated cardiomyopathy. 
• Keep your pet in good body condition and allow your pet to exercise appropriately.   
• If you learn that one of your pet’s relatives has been diagnosed with cardiomyopathy, ask your family veterinarian about the benefits of screening for heart disease via a blood test called proBNP or via an echocardiogram (ultrasound of the heart). 

If you have any questions about your pet’s heart health, talk to your family veterinarian. After confirming any heart-related problem or disease, your family veterinarian may provide a diagnosis and treatment options or refer you to a board-certified veterinary cardiologist.