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.

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

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