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Cats with heart conditions, Feline Cardiomyopathy and congenital defects

I have not published any articles for a while and the main reason  was the disease of my cat Strudel. He passed away 12 days ago and we still feel devastated. A diagnosis of heart disease is something you would never want to hear from your veterinarian, especially if it comes from an urgent emergency trip to the Vet Emergency.

Fortunately, they could remove the fluids, and Strudel remained under observation for 8 hours. He was alive for now, but the vet was very clear: you can gain some time with a certain quality of life, but the prognosis is bad, we are talking about months, he has RCM (Restrictive cardiomyopathy). Here in this video you can see his difficult breathing due to his heart not working well and the fluids in his lungs.

In the last week of January this year, we had to run with our cat Strudel to the emergency vet room. I noticed he was not breathing as usual, his chest expanded too much, like making an extra effort to get more oxygen. Something inside me (cat mama instinct) told me that this would not end well, so it was.  The diagnosis was Congestive Heart Failure, massive fluid around the lungs, and the veterinarian at ER (Veterinary Emergency & Referral Group) suggested to put him to sleep or try to save his life. Of course, our first reaction was: “Save him!”, but how we ended like this, he was perfectly fine, how was this possible?

In this article, I will explain, in the most easy way as possible, the most common heart diseases in cats that I could research from veterinary material and my experience with my cats. To clarify, I am not a veterinarian, neither recommend any treatment or medication and always, you must bring your pet to professionals.

“Heart disease, the same as cancer, is a cruel diagnostic for pets and humans.”

From that moment, we dedicated our lives during eight months to give him the best quality of life possible. But on the 16th of September of this year and after a roller coaster of emotions and more ER urgent visits, he decided to be free from his fragile body.

After reading Strudel’s vet reports and googling all the information I could, I discovered that RCM(Restrictive Cardiomyopathy) was a rare variation in the cardiomyopathy classification, with not a very good prognosis. In addition there are two other classifications and congenital defects out of this category.

What we have learnt

Cardiovascular disease in cats are divided in:

  • Congenital heart defect

 It is not very common(<1% cats) and can produce heart failure in kittens, which don’t survive more than a year. Detecting a murmur or when the kitten goes into heart failure can expose congenital heart defects. Depending on where the defect is in the heart, the symptoms and risk level can be different, but only your vet or a vet cardiologist can discover it with an EKG, X-rays and echocardiograms.

When early detection, it may be a chance for surgery, or if it is a mild condition, it can be treatable.

  • Cardiomyopathies
    It means “disease of the heart muscle,” and according to Marc Kraus, DVM, a senior lecturer in cardiology at Cornell University’s College of Veterinary Medicine. The heart muscle either grows too thick to function properly or it stretches and becomes too thin.

It is very common in young to middle-aged cats and the major cause of heart diseases presented in different forms:

HCM - Hypertrophic Cardiomyopathy

It is the most common of the three cardiomyopathies, where the walls of the left ventricles become thick. The heart function is poor, and obstruction of the blood flow may occur, known as Feline Aortic Thromboembolism, meaning the possible presence of a blood clot in an artery.

HCM is characterized by concentric hypertrophy and fibrosis of the left ventricle and causes stiffening of the ventricle, which prevents relaxation and impairs ventricular filling during diastole, according to Meg Sleeper, VMD, DACVIM (cardiology), at the University of Florida College of Veterinary Medicine in Gainesville.

The cause is not certain, but there is a strong likelihood of hereditary influence. It tends to affect more males between 1 to 5 years of age; however, it can be different in the following breeds: Main Coon Cats, Ragdolls, British Shorthairs, American Shorthairs, and Devon Rexes.

In Main Coons and Ragdolls, the cause is a genetic defect in a protein inside the heart muscle. A test for these cats can be made in the Veterinary Cardiac Genetics Laboratory at Washington State University College of Veterinary Medicine.

Maine Coon

There are no early signs of HCM; more advanced disease may provoke murmurs, increasing the heart rate. If your cat is lethargic and has a diminished appetite and shows difficulty breathing, it could be CHF (congestive heart failure), and you should bring him to the vet ER as soon as possible. He/She may need to be hospitalized, receive oxygen treatments, or have the excess fluid drained with a catheter (a process called thoracentesis).

The treatment will depend on the stage of illness of your cat and other factors. In general, veterinarians use the same drugs that are used for people, and yes, humans can suffer the same cardiomyopathies than pets.

Diuretics, calcium channel blockers, and ACE inhibitors can be chosen by your vet, also beta-blockers that may help the heart muscle relax by slowing the patient’s heart rate, thereby decreasing its need for oxygen. Additionally, a low salt diet can be prescribed sometimes, but not all cats love this type of food.

RCM - Restrictive Cardiomyopathy

Dr. Sleeper said that the disease is characterized by focal, regional fibrosis of the left ventricular myocardium, causing stiffening of the left ventricle and inhibiting passive filling during diastole. Unlike HCM, restrictive cardiomyopathy does not cause ventricular wall thickening, as you can see in the images here.

Scar tissue and inflammation, in some cases, may be responsible for this heart muscle behavior. Cats with this condition are at high risk of developing clots and congestive heart failure, like my cat Strudel, who had a clot inside his heart.

The causes of RCM are unknown, it is more frequent in cats from middle age to older ones, and the prognosis is poor, the CHF is difficult to control, and the drug resistance is very common in this cardiomyopathy.

In my cat Strudel, there were no initial signs, not even a murmur; his first symptoms were directly CHF (congestive heart failure) with pleural effusion (his lungs were full of fluids). As the first line of treatment, veterinarians usually use a Thoracentesis procedure to remove fluids when the life of the cat is at risk.

Chronic therapy of the cat with RCM is centered on the management of CHF, the same drugs like in HCM are used, and continuous monitoring of respiratory rates and level of activity.


DCM - Dilated Cardiomyopathy

Dilated cardiomyopathy occurs when the heart muscle loses its tone and becomes flaccid, which results in a decreased forward flow of blood from the heart and, consequently, heart failure.

The disease was once common in cats but has become quite rare since the association between DCM and insufficient dietary taurine was discovered. 

The taurine essential amino acid is concentrated in animal tissue. People who feed their cats with dog food or grain-based diets put their cat at risk of DCM.

Another cause is myocarditis (inflammation of the heart muscle), in humans, the cause is linked to virus or autoimmune disease, but in cats still is not very clear.

DCM is more common in Abyssinian, Burmese, and Siamese cats than in other breeds.


In cases when DCM is caused by nutrition deficiencies, the veterinarian will try to correct any taurine deficiency and control fluid retention.

Hearth Cardiomyopathy Subtypes

Cardiomyopathy and kidney disease

Diuretics which are mostly used as a treatment for congestive heart failure, should not be given without veterinarian consent and monitoring. It can be contraindicated in animals suffering from kidney failure or those that are dehydrated. It should be used with extreme caution when electrolyte abnormalities, liver disease, or diabetes mellitus are also present.

Diuretics act upon the kidneys, causing increased excretion of both electrolytes and fluids, generating a big extra effort in their natural function.


There are some supplements in the market labeled “to help the heart function”, but my cat cardiologist was very honest about it. Although veterinarians don’t recognize any advantage in the use of supplements, he let me use the ones I mentioned to him (like if it was something more related to calming my frustration and having the feeling I was doing something for my cat). The instruction was to not give him his current medication at the same time that the supplements. Even gabapentin I was not able to use it to manage my cat’s anxiety on a vet trip since it can interfere with my cat’s behavior at the moment of medical evaluation.

His concern came from the fact that some supplements can interfere with the absorption of cats’ medication, so you should never administer supplements with drugs at the same hour.

I recommend you talk with your veterinarian before using any supplements or extra drugs if your cat has cardiomyopathy.

I read that some people give their cats extra pills of furosemide (diuretic) to control heart failure, and in my experience, this is too risky unless your veterinarian indicates so. Furosemide in my cat Strudel only did effect at the beginning of his disease, but then it only worked combined with other drugs. Also, their bodies can develop drug resistance. On the other hand, you must be aware of what is your cat’s kidney situation, so I think the cardiologist is the best one to tell you what you can do in every situation.

How much time will my cat live?

Unfortunately there is no answer, I knew cases where the prognosis was about four or five months, but with good care and strict veterinarian control, cats have been able to live more than 1 year or even more.

My Strudel could live eight wonderful months full of love and extra care, taking 21 pills a day but free of pain.

I believe that it is more about quality than longevity. We know how stressful and devastating it is, we were there; waking up during the night several times for his meds, unable to leave the house and constantly monitoring his condition, food, and urgent visits to the vet emergency room. 

Although we still have our hearts full of sorrow and sadness, we enjoyed each moment with him as a miracle gift with unconditional love. He may be living his next adventure crossing the rainbow while we treasure his sweet memories, knowing that some day we will be all together.


  • J.D. Bonagura (1997) Feline restrictive cardiomyopathy, Veterinary Quarterly, 19:sup1, 3-4, DOI:                    10.1080/01652176.1997.9694775
  • Cornell University, College of Veterinary Medicine, Cornell Feline Health Center
  • Cat Owners’s Home Veterinary Handbook. Third Edition. Debra M. Eldredge, MVD. Delbert G. Carlson, DVM. Liisa D. Carlson, DVM. James M. Giffin, MD.
  • cavalier Health Organization