Hypertrophic obstructive cardiomyopathy in cats is a very serious condition caused by an abnormal thickening of the heart's left ventricle which results in a number of life-threatening symptoms. Today our Corpus Christi emergency vets explain more about HC in cats and how it is treated.
Your Cat's Heart
The heart of your cat is divided into four sections, each of which has a special function to perform. The left ventricle is the name for the bottom left chamber of the heart. This area is in charge of drawing oxygenated blood from the lungs and pumping it to every part of your cat's body that needs it.
While the left ventricle is naturally thicker than the other 3 sections of the heart due to its immense workload, hypertrophic cardiomyopathy occurs when there is an abnormal thicking of the muscles of the left ventricle which then negatively impacts the heart's ability to pump the blood out into the body.
Are some cats more prone to developing hypertrophic cardiomyopathy?
Due to a gene mutation in one particular (very large family line), Maine coon cats have been found to be predisposed to developing hypertrophic cardiomyopathy. Persians and American Shorthairs may also seem to have a higher risk of the illness, but more research is needed to confirm this.
Male cats are more likely than females to suffer from hypertrophic cardiomyopathy, and the condition is most often diagnosed in cats between 5 - 7 years of age although cats of almost any age can have the disease.
What causes hypertrophic cardiomyopathy in cats?
Although the exact causes of hypertrophic cardiomyopathy in cats are still largely unknown, genetic mutations and predispositions in some breeds have been linked to the condition. High blood pressure and/or hyperthyroidism can cause additional complications in cats with hypertrophic cardiomyopathy, even though they have not been proven to be a direct cause of the condition.
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)
- Lethargy
- 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 a clot in the terminal aorta
- Bluish discoloration of the pads of fee and nailbeds (due to lack of oxygen flow to the legs)
- Collapse
- 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 possible abnormalities in the heart's electrical conduction. EKG testing can also help your vet to determine the origin of any abnormal heart rhythms detected.
To be clear, an EKG might not be enough to diagnose hypertrophic cardiomyopathy. For visually inspecting the heart for enlargement, thickening of the walls, or other telltale signs of the condition, X-rays and ECG (echocardiograph) performed with ultrasound imaging technology are typically more helpful.
Your cat's blood pressure will be checked to rule out hypertension, and blood testing will be performed to test for high levels of thyroid hormones. High levels of thyroid hormones are linked to hyperthyroidism in cats which can lead to many of the same symptoms as hypertrophic cardiomyopathy.
What is the treatment for hypertrophic cardiomyopathy in cats?
To best manage the condition, cats with hypertrophic cardiomyopathy are frequently hospitalized. Your cat will be kept warm, relaxed, and comfortable while in the hospital and may receive oxygen therapy to assist with breathing. One or more of the following treatments may also be used during treatment:
- Diltiazem slows the heart rate, treats irregular heartbeats, and helps 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
Note that the treatment used for your cat with hypertrophic cardiomyopathy will depend upon your kitty's unique symptoms, overall condition, and any other conditions that may also be impacting your cat's health.
What is the life expectancy for cats with hypertrophic cardiomyopathy?
A prescription low-sodium diet and a peaceful, relaxing environment can be part of home care. You must keep an eye out for your cat's symptoms of breathing problems, weakness, lethargy, appetite loss, limb weakness, or paralysis.
Ongoing veterinary care and testing will also be required to ensure that treatment is effective and to monitor your cat for any possible side effects such as poor kidney function or bruising.
The prognosis for cats with hypertrophic cardiomyopathy is mixed based on the severity of your cat's condition and other factors that affect your cat's overall health. Your vet will be able to provide you with a realistic prognosis for your kitty. But it is important to talk to your vet quickly, as sudden death in cats from hypertrophic cardiomyopathy can occur thanks to clots and/or severe arrhythmia.
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.