Heart disease in pets can appear in many forms, and cardiomyopathy is among the most common. Cardiomyopathy is a disease of the heart muscle brought about by structural abnormalities. These abnormalities can result in serious heart dysfunction, and even lead to heart failure in some pets.
There are three types of cardiomyopathy -- hypertrophic, restrictive, and dilated. In cats, hypertrophic cardiomyopathy is the most common acquired heart disease. It is much less common in dogs. Here we will look at the causes, symptoms, and treatment of hypertrophic cardiomyopathy in cats and dogs.
Causes of Hypertrophic Cardiomyopathy in Cats and Dogs
Hypertrophic cardiomyopathy is characterized by a thickening of the heart’s muscle walls. The degree of thickening will determine the severity of the disease. In some cases, the thickening may affect the heart’s ability to adequately pump blood, resulting in a buildup of fluid that is ultimately forced into the lungs and chest, causing congestive heart failure.
Other consequences of hypertrophic cardiomyopathy may include arrhythmias (irregular heartbeat) or feline aortic thromboembolism, which is a painful condition caused by a blood clot in the aorta that cuts off blood supply to the legs.
In cats, hypertrophic cardiomyopathy is thought to be inherited, and a specific mutation has been identified in Maine Coons and Ragdolls. Other purebred cats can also be predisposed, but the Domestic Shorthair -- which is the most commonly owned house cat in the US -- is the type most often diagnosed with the condition. Affected cats are usually middle-aged or older.
In dogs, the causes of hypertrophic cardiomyopathy are not well understood, but it tends to strike dogs 3 years of age or younger, as well as older Boston Terriers.
Symptoms of Hypertrophic Cardiomyopathy in Cats and Dogs
The symptoms of hypertrophic cardiomyopathy vary depending on the severity of the disease. In addition, many cats are very good at hiding their illnesses, which means that routine check-ups at the veterinarian are incredibly important for identifying any problems.
If your pet does show symptoms, they may be subtle or secondary to a complication of the disease. These symptoms may include:
- Increased respiratory rate
- Decreased appetite
- Difficulty breathing (secondary to congestive heart failure)
- Exercise intolerance (secondary to congestive heart failure)
- Coughing (secondary to congestive heart failure)
- Leg paralysis (secondary to a blood clot)
- Your veterinarian may hear an increased heart rate, heart murmur, and/or heart gallop
If your pet ever exhibits difficulty breathing or paralysis, it is an emergency and you should seek out veterinary attention right away.
Diagnosing and Treating Hypertrophic Cardiomyopathy in Cats and Dogs
In order to diagnose hypertrophic cardiomyopathy, your veterinarian will start by performing a physical exam in which they listen your pet’s heart for increased heart rate or a heart murmur or gallop. Most pets will then undergo testing, including an echocardiogram (heart ultrasound) to evaluate the structure and function of the heart and an electrocardiogram or radiograph to provide additional structural information.
Maine Coon and Ragdoll cats who are suspected to have the condition may undergo a genetic test to check for the mutated gene.
Additional tests may be carried out to rule out other diseases that can cause similar problems in the heart, including hyperthyroidism and hypertension.
Once the condition has been diagnosed, treatment will be discussed. If the pet is suffering from an underlying condition such as hypertension, that condition will need to be treated the heart disease may resolve.
If there is not an underlying condition, it is important to understand that hypertrophic cardiomyopathy cannot be cured -- the thickening of the heart muscle is irreversible. However, depending on your pet’s condition, some veterinarians may recommend medications to manage the condition and improve the hearts function. These medications may include:
- Beta-adrenergic blockers, such as Atenolol, and calcium-channel blockers These types of medications slow down the heart rate which improves the heart’s ability to pump blood and reduces the amount of oxygen used by the heart. They can sometimes also improve arrhythmias.
- Pets suffering from congestive heart failure may be treated with diuretics to remove excess fluid or ACE inhibitors which dilate blood vessels, allowing for better blood flow.
- Pets who are at risk for blood clots may be treated with anticoagulants.
What Happens to Pets with Hypertrophic Cardiomyopathy
The prognosis for hypertrophic cardiomyopathy can vary. It is important to keep an eye on your pet and monitor their condition. Your veterinarian may show you how to check your pet’s respiratory rate so that you can contact them if the condition seems to be worsening. In addition, all pets with heart disease will require frequent check-ups, especially in the beginning stages when the course of treatment is still being assessed.
Never hesitate to contact your veterinarian if you have questions about your pet’s heart health.
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