Hypertrophic cardiomyopathy in cats is a potentially fatal condition caused by an abnormal thickening of the heart's left ventricle, which causes a variety of life-threatening symptoms. Learn more about treatments for cats.
Your Cat's Heart
Your cat's heart is divided into four distinct sections, each with a distinct and vital role to play. The left ventricle is the bottom-left section of the heart. This section is in charge of receiving oxygenated blood from the lungs and pumping it to all parts of your cat's body that require it.
While the left ventricle is naturally thicker than the other three sections of the heart due to its heavy workload, hypertrophic cardiomyopathy occurs when the muscles of the left ventricle thicken abnormally, impairing the heart's ability to pump blood out into the body.
Are some cats more prone to developing hypertrophic cardiomyopathy?
Due to a gene mutation in one specific (very large) family line, Maine coon cats have been shown to be predisposed to developing hypertrophic cardiomyopathy. The disease appears to be more prevalent in American Shorthairs and Persians, but more research is needed to confirm this.
Male cats are more likely than females to develop hypertrophic cardiomyopathy, and the condition is most commonly diagnosed in cats aged 5 to 7 years old, though cats of any age can be affected.
What causes hypertrophic cardiomyopathy in cats?
The causes of hypertrophic cardiomyopathy in cats are largely unknown, but genetic mutations and predispositions in some breeds have been linked to the disease's occurrence. While not proven to be a direct cause of the condition, high blood pressure and/or hyperthyroidism can lead to additional complications in cats with hypertrophic cardiomyopathy.
What are the signs of hypertrophic cardiomyopathy in cats?
If your cat is suffering from hypertrophic cardiomyopathy the following symptoms may become apparent:
- Loss of appetite (anorexia)
- Weak pulse
- Difficulty breathing
- Shortness of breath, snapping or crackling sounds when breathing
- Abnormal heart sounds (muffled, galloping rhythm, murmurs)
- Inability to tolerate exercise or exertion
- Sudden hind-limb paralysis with cold limbs due to clot in the terminal aorta
- Bluish discoloration of the pads of fee and nailbeds (due to lack of oxygen flow to the legs)
- Sudden heart failure
How do vets see hypertrophic cardiomyopathy in cats?
EKG testing can be used to examine the electrical currents in the heart muscles and may reveal abnormalities in the electrical conduction of the heart. EKG testing can also assist your veterinarian in determining the cause of any abnormal heart rhythms detected.
However, an EKG may not be enough to make a definitive diagnosis of hypertrophic cardiomyopathy. Ultrasound imaging technology is typically more useful for visually inspecting the heart for enlargement, thickening of the walls, or other tell-tale signs of the condition than X-rays and ECG (echocardiograph).
To rule out hypertension, your cat's blood pressure will be checked, and blood testing will be performed to look for high levels of thyroid hormones. Thyroid hormone excess has been linked to hyperthyroidism in cats, which can cause many of the same symptoms as hypertrophic cardiomyopathy.
What is the treatment for hypertrophic cardiomyopathy in cats?
Cats with hypertrophic cardiomyopathy are typically hospitalized in order to treat the condition as effectively as possible. Your cat may be given oxygen therapy to help with breathing while in the hospital, and he or she will be kept warm, relaxed, and comfortable. One or more of the following treatments may also be used as part of the treatment:
- Diltiazim to slow the heart rate, treat irregular heartbeats, and help in the reduction of the enlargement in the left ventricle
- Beta-blockers slow the heart rate, help correct irregular heartbeats, and control blockage of the blood flow.
- Ace inhibitors, in cases with congestive heart failure to help improve the flow through the ventricle
- Aspirin to help decrease your cat's risk of blood clots
- Warfarin to prevent blood clotting
- Furosemide as a diuretic to help remove excess fluid from your cat's body
- Spironolactone - a diuretic used sometimes in conjunction with furosemide - for cats with congestive heart failure
- Nitroglycerin ointment, to improve flow by dilating (opening) the ventricle and arteries
It is important to note that the treatment used for your cat with hypertrophic cardiomyopathy will be determined by your kitty's specific symptoms, overall condition, and any other conditions that may be affecting your cat's health.
What is the prognosis for cats with hypertrophic cardiomyopathy?
A prescription low sodium diet and a quiet relaxing home environment may be included in-home care. You must keep an eye on your cat for any signs of difficulty breathing, weakness, lethargy, loss of appetite, limb weakness, or paralysis.
Ongoing veterinary care and testing will be required to ensure that the treatment is effective and to monitor your cat for any potential side effects, such as poor kidney function or bruising.
The prognosis for cats with hypertrophic cardiomyopathy is mixed, depending on the severity of the condition and other factors affecting your cat's overall health. Your veterinarian will be able to give you an accurate prognosis for your cat.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.