What is heart disease?
Heart disease refers to any abnormality of the structure or function of the heart. The heart can be divided into five functional components:
- The heart muscle pumps blood around the body
- The heart valves keep blood flowing in the right direction
- The heart’s electrical system coordinates heart muscle contraction and keeps the heartbeat regular
- The major vessels carry blood into and out of the heart (pulmonary vein and aorta)
- The pericardium is a sac that surrounds and protects the heart
Heart disease can affect any or all of these parts.
What are the signs of heart disease in cats?
Most cats display no clinical signs until heart disease is advanced. Unlike humans and dogs, cats rarely cough if they have heart disease. Exercise intolerance occurs but can be difficult to recognize, since cats rarely go for walks or engage in sustained physical activity with their owners. As disease advances and exercise tolerance decreases, cats tend to become more withdrawn, hide under furniture, and sleep more.
The most common signs of heart disease in cats are:
- Poor appetite
- Weight loss
- Lethargy
- Increased respiratory rate and effort
- Sudden collapse
- Sudden, painful hind-leg paralysis
- Stunted growth in kittens
- Heart murmur (may or may not be present)
Is a heart murmur always a sign of heart disease?
A heart murmur is an extra sound caused by abnormal or turbulent blood flow in the heart or blood vessels exiting the heart. It can be caused by structural problems in the heart (pathologic murmur) or may occur secondary to other changes like anemia (innocent murmurs). Some heart murmurs can indicate heart disease but others are not caused by heart disease. Many cats with heart disease have no murmur.
What types of heart disease occur in cats?
One way to categorize heart disease is to split it into congenital disease, where there is an abnormality at birth, and acquired disease, which develops later in a cat’s life.
Examples of congenital heart disease include:
- Valve malformations
- Abnormal connection between the aorta and the pulmonary artery (patent ductus arteriosus)
- Defects in the heart wall that divides the right and left sides of the heart (e.g., ventricular septal defect [VSD])
Examples of acquired heart disease include:
- Hypertrophic cardiomyopathy
- Restrictive cardiomyopathy
- Dilated cardiomyopathy
- Secondary cardiomyopathy due to hyperthyroidism
Are some cat breeds at higher risk of heart disease?
Heart disease can occur in any cat, but certain breeds may have an increased risk of developing specific heart conditions including:
- Hypertrophic cardiomyopathy: American And British Shorthair, Bengal, Burmese, Domestic Shorthair, Maine Coon, Persian, Ragdoll, Siamese, Sphynx
- Restrictive cardiomyopathy: Burmese, Maine Coon, Norwegian Forest, Persian, Siamese
- Ventricular septal defect: Domestic Shorthair, Maine Coon
How is heart disease diagnosed?
Your veterinarian may recommend additional testing based on clinical signs or if they detect a murmur. Additional testing may include:
- X-rays (radiographs)
- An electrocardiogram (ECG), which records the heart’s electrical activity
- An echocardiogram (cardiac ultrasound)
- Blood tests
If your veterinarian suspects that the heart murmur is secondary to another disease, more extensive tests may be recommended.
Can heart disease be detected early?
Several genetic tests are available to identify cats that may be more likely to develop certain types of heart disease; however, they are not useful for every cat. Talk to your veterinarian about whether genetic testing would be useful for your cat.
If genetic testing shows your cat is at higher risk, your veterinarian may recommend regular blood screens and echocardiography to detect changes in your cat’s heart before they feel sick. The most important step in finding heart disease early is recognizing the signs and seeking veterinary care as soon as possible so treatment can begin right away.