Feline Hypertrophic Cardiomyopathy (HCM) is a condition that causes the muscular wall of a cat’s heart to thicken and become stiff. This reduces the heart’s efficiency and sometimes creates symptoms in other parts of the body.While some specific breeds of cats (Maine Coon, Ragdoll, British Shorthair, Sphynx, Chartreux and Persian cats) can have higher incidence of the disease, HCM is diagnosed most commonly by veterinarians in mixed
breed cats.

The effects of HCM vary considerably from cat to cat. Most cats with HCM do not appear ill and estimates suggest that upwards of 50% of cats with HCM do not have a heart murmur or abnormal heart rhythm (arrhythmias) that would suggest heart disease during a physical exam. Other cats do have murmurs and arrhythmias and some develop congestive heart failure, where fluid builds up in the lungs and/or in the chest cavity around the lungs.  These cats usually exhibit labored breathing and lethargy. A serious and potentially life-threatening consequence of HCM is the formation of blood clots in the heart. These clots can break loose from the heart and travel via the blood vessels to other parts of the body where they can obstruct blood flow – this is called Thromboembolism. This often occurs suddenly in the hind legs, causing severe hind leg pain, weakness/paralysis and hind limbs that may be cool to the touch. While there is no cure for HCM, accurate diagnosis and appropriate management can improve quality of life for affected cats by controlling symptoms and reducing the chance of a thromboembolism event.

With up to 50% of cats with HCM not showing symptoms or abnormal heart sounds on exam, many affected cats are diagnosed only after serious or life-threatening signs appear. Interestingly, some cats with heart murmurs have what are referred to as “innocent murmurs” that are not associated with heart disease. For these reasons, a test that helps screen apparently healthy cats for HCM has been developed. The CardioPet pro-BNP blood test screens for a metabolite (pro-BNP) that appears in the blood when the heart muscle is stretched or stressed. When blood levels of pro-BNP are elevated, it suggests that heart disease may be present, even in those cats without murmurs or any symptoms.

Redwood Veterinary Hospital has negotiated with our reference laboratory and obtained some special pricing for this test when it is run with Annual Wellness bloodwork. We’re calling this new panel the Feline Wellness + BNP lab panel and it costs $129.76. This set of tests includes a complete metabolic chemistry panel and CBC which serve as a system-wide check of the major organ systems and cell counts, as well as the pro-BNP test to check for possible hidden heart disease. For the cost this panel is an unusually complete blood screen.  Our doctors recommend this panel be done in lieu of regular Annual Wellness bloodwork for cats over 3 years of age and cats with heart murmurs that have not been previously worked up.

An increase in blood levels of pro-BNP is not diagnostic for Feline HCM. Rather, given the hidden nature of HCM in some cats, pro-BNP serves as a marker that identifies those patients that may need a closer evaluation of their heart.  If the pro-BNP is elevated or the patient has other symptoms suggestive of heart disease, a definitive diagnosis of HCM is determined using echocardiography (heart ultrasound).  This technology produces an image of the beating heart and allows us to measure the thickness of the heart wall and the size of the heart chambers. Your pet’s doctor will use these measurements to determine if your cat has HCM and if any treatment is needed.

Some cats with HCM do not progress to more serious stages of heart disease and often times no medications are used. In these cases, owners are instructed to monitor their cats closely for lethargy, labored breathing, and even mild increases in respiratory rate while sleeping as these can be indicative of heart problems.

As always, feel free to call and speak to a doctor about any questions or concerns you may have about the health of your pet(s). We’re always happy to talk on the phone but keep in mind that we will likely need to examine your pet to specifically address his or her unique health concerns. If you would like to schedule your cat for a Wellness Exam and a Feline Wellness + pro-BNP lab panel, please give us a call at 707-553-1400.