Feline hypertrophic cardiomyopathy


Feline hypertrophic cardiomyopathy (hcm) is a disease affecting cats in which the walls of the heart become increasingly enlarged.

This dossier compiles information on the disease for veterinarians and pet owners (as originally hosted on dsl.org since 1997), and includes an updatedlist of other good HCM Internet resources. (Standard disclaimer applies: I’m not a vet and this is not medical advice.)

Diagnosis in early stages can be tricky, but here are the symptoms: lethargy, poor appetite, panting/troubled breathing. Often, a feline will develop a heart murmur along with HCM; while the HCM can be treated if detected early, the murmur will probably never go away (but it isn’t anything to worry about).

Even after treatment, weakness or paralysis of the back legs should be watched for — blood clots can be developed and lodged in each leg (“saddle thrombosis”). This is a grave condition and must be treated immediately (within minutes, maybe hours at best) for the feline to survive.

Prognosis is not favorable — no cure is known at this time. In a fairly recent study, cats with HCM lived for an average of around 736 days, but I’ve heard of HCM-afflicted cats living for four or more years before heart failure.

If diagnosed early, medication can slow the process down. Late diagnosis is usually postmortem, or when the disease has reached an acute state.

The cause of HCM is believed to be genetic. It has been noted that an alarming increase of cats (and dogs), especially younger ones, afflicted with HCM in recent years.

The best hope for HCM, it seems, is to diagnose animals which carry the HCM gene and don’t let them breed.

Poll Results: Who bred your HCM-afflicted cat?

  • 7% - Pet store or other corporate breeder (11 votes)
  • 11% - Friend, family member, or other indivdual (18 votes)
  • 20% - Professional cattery (32 votes)
  • 62% - Unknown (obtained from animal shelter, etc) (99 votes)

(Poll presented on 1999-11-30; 160 votes total)

Cat Fanciers’ Association have also published advice to breeders on HCM.

Treatment is through medication to both thin the blood and retard the growth of the heart wall. Several types of vet-prescribed medications can be administered: atenolol (generic for tenorim, a beta blocker, which lowers blood pressure), lasix or other diuretic, and Cardizem. Baby aspirin (normally fatal to cats) can be given twice a week to thin the blood.

It can be a struggle getting the medication down the hatch, and few cats seem to be easily “tricked” into eating food laced with meds. The best technique is to kneel on the ground with your feet crossed, the cat held between your knees. Open the jaw with one hand and insert the medication with the other. It can also help to give meds before they eat their first meal of the day, to reduce the chance of vomiting it up.

Matthew Soffen offers some good advice here. He says that if you can find a Compounding Pharmacy, it can be helpful: they can create a liquid version of the medication. He says that they can get them in various flavors (fish, bacon, cheese, beef, and so on) which make it appealing to the cats and is easy to adminster.

It may be appropriate, later down the line, to take the cat off diuretics (which act as an appetite supressant and can also dehydrate the cat).

Other treatment is focused on encouraging strength and optimum health by giving the feline the best living conditions possible; this also happens to be sound advice even for cats who aren’t sick — a diet of name-brand, commercial pet food is probably worse for cats than a human on a diet of fast food:

  1. Feed high-taurine, quality foods. Commercial cat foods that seem to meet standards include Bench & Field, Nature’s Recipe, Wysong, Katz-n-flocken. (Who else? Diamond Pet Foods’ Naturals? Premium Edge Cat Food?)

  2. Other healthy foods reported to be liked by some cats include plain, cooked oatmeal; steamed broccoli; cooked liver. Avoid salt and salty foods. (Proper diet for HCM-afflicted cats is of utmost importance.)

  3. Exercise should be with caution (feline should not be stressed), but is also important.

  4. Give several holistic treatments — these are all from The Natural Cat by Anita Frazier, a book I highly recommend; Frazier’s book has been a great success and was published in several editions. The very latest edition, updated with new co-author Norma Eckroate, is now on sale at a discount at Amazon. If you’re serious about treating HCM you should use this book. It’s well worth it.

    Here’s just some of treatments for HCM explored in this book:

    • Vitamin E supplements in wet food

    • Make your own Vita-Mineral Mix (recipe given in book) and add to food

    • Give weekly or daily “kombu broth” mixtures (recipe in book)

    • Daily supplement of “Pet Tinic” (rich in B-complex vitamins)

    • Hawthorne berry supplement, a mild diuretic, to encourage self-confidence

    • More herbal supplements and treatments are given on Holisticat’s HCM page (see below). One important supplement to investigate is dandelion, a natural diuretic.

Anecdotes and updates

In May 2010, Matthew Soffen reported that his cats, who were diagnosed with HCM four years ago, are currently doing fine and only need an annual trip to a veterinary cardiologist.

Carrie Sparks wrote in to say that her cat had been diagnosed at seven years of age, and with a treatment of Cardizem and baby aspirin she lived until almost nineteen!

Here’s another positive anecdote from Robert Durlak on his barely one-year-old cat, “Y,” who’d been diagnosed with HCM in 1995 after going into heart failure:

Fortunately, there’s an animal cardiologist in my area, a fellow named Joel Edwards, who is apparently very highly regarded in vet circles as a pioneer researcher. The cat was put on a rigorous dosage schedule of lasix, enacard, diltiazem and Ipropanol as well as thrice daily applications of nitro paste in his ears for six months. At this point, he only gets enacard and diltiazem with an occasional portion of baby aspirin. He was raised on science diet, so there was no real need to alter his food.

In X-rays, his heart walls have decreased in size about 60%, and other than limiting his exercise, he’s doing very well. His reversal may be a bit of an anomaly regarding this disease… even Edwards is surprised at how well the cat is doing.

Knusper, the feline tiger pictured above, was diagnosed with HCM in Dec. 97. He’s quite well now, after it was determined in 2001 that his “illness” was actually a misdiagnosis! The medication took away his appetite and he got thinner and thinner … until he was completely taken off all medication and then immediately sprung back to his former lively, roly-poly self.

For further reference

  • feline-heart is “a list where members can discuss feline heart conditions and treatments.”

  • JAChinitz has a huge site on feline hcm that includes a valuable, one-page information sheet in PDF format that you can download and print.

  • A “succinct review” for veterinarians by Chuck Newman, PhD DVM, explains the difference between the less common dilated cardiomyopathy and hypertrophic cardiomyopathy, gives clinical signs and detailed information on medication and treatment. Dr. Newman has also put up illustrations on this page.

  • A site with good HCM info, dedicated to the memory of the cat Mickey.

  • Clear, concise page discussing treatments for “the silent killer” from the UK’s Feline Advisory Bureau.

  • West Boulevard Veterinary Clinic (Vancouver) has an informative page about HCM, the “silent killer.”

  • Hypertrophic Cardiomyopathy Association — for humans, but good general info on the disease.

  • MedLine search abstracts on feline HCM.

  • HOLISTICAT is a mailing list for discussing holistic feline care; there’s quite a bit of HCM discussion on the list, as it has unfortunately become quite a common feline disease. Check the HOLISTICAT site for subscription instructions.

  • Do this Google search on feline HCM to list up-to-date sites.

First published on June 9th, 2010 at 9:12 am (EST) and last modified on June 9th, 2010 at 10:34 am (EST).