Heart Murmur in Cats


Heart Murmur in Cats

Heart Murmur in Devon Rex

Question: Hello Dr. Mike, I feel almost in desperate need for someadvice. I just got a new kitten, and he's a devon rex named Larry. He's only about 15 weeks old and was just diagnosed by his vet as having a heart murmur. The vet wasn't sure how serious it was because he didn't know very much about the breed, and it wasn't a clear cut good/bad murmur. He said that is was fairly faint when Larry's heart rate was down and became more noticeable as his heart rate went up. I'm taking him back to the vet in three weeks to hear it again and possibly schedule some tests. I cannot explain to you how attached to Larry I've become in the short amount of time I've known him, and am traumatized at the concept of maybe losing him to a heart problem. My question for you is, i know you can't tell me whether or not he'll be alright or what type of murmur it is, but what is the incidence of heart murmurs in kittens, what is the percentage that it's benign as opposed to fatal, etc... I know absolutely nothing, and I also don't know if maybe it's something with the breed. The devons are an unusual breed, and maybe you know something about them. If you know anything, i'd be very appreciative. Thank you.

Sincerely, Erika


I have not been able to find a list of congenital heart problems by cat breed but I will keep looking for something, because there are such lists for dogs.

Cats have heart murmurs for many reasons. There is even a described disorder in cats in which there is a murmur that gets louder with exercise or excitement but for which no underlying heart disease can be identified. Unfortunately, this pattern of murmur is also recognized as occurring with cardiomyopathy in cats, which is the most common cause of heart murmurs and usually will lead to later problems.

We have several cats in our practice who have had heart murmurs all their lives without any apparent problems from them and at least one of these cats is well into his teens. We see cats with hypertrophic cardiomyopathy who have problems by the time they are several months old.

The only really good way to identify the cause of a heart murmur in cats is an ultrasound exam. It can be really hard to identify the cause, even with this technology. For this reason, it is best to have this examination done by a veterinary cardiology specialist. It is worth traveling a long way, if necessary, to have this examination done. Knowing the type of problem leading to the murmur makes it possible to do a better job planning for possible complications and gives a much better idea of the prognosis.

Several of my clients have been unable to afford going to a cardiologist. In this circumstance it is possible to monitor over time for signs of heart failure and to treat as necessary. It is more worrisome but it is an acceptable approach to this problem if it is not possible to get an accurate diagnosis.

If you would like to pursue a diagnosis faster than the schedule your vet has laid out, ask for referral to a veterinary cardiologist. It is reasonable to do that once it is clear a murmur is present in a young kitten.

Mike Richards, DVM 8/4/2000

Heart murmur in Bengal kitten

Question: Dr. Mike,

Is it absolutely necessary to do x-rays, etc. before spaying/neuturing a Bengal kitten if it has a Grade 1 heart murmer? My 5 month female has a murmer and I wanted to get her spayed by the end of May (6 months old). I'd rather wait for the murmer to hopefully "go away" than pay costs for x-rays, etc. When will she go into season? I also have a 15 week old male kitten. I don't want them to spray the house or breed. I'll have him neutured at 6 months also. Are heart murmers common? I've looked at 4 kittens and all have had one. Can they tell from the x-ray alone how bad the condition is? How costly can it be?

Answer: M-

X-rays are not very helpful in determining the cause or severity of a heart murmur. It is much better to consider ultrasound examination by a cardiologist or someone familiar with cardiac ultrasound examinations. This is the only really good way to determine the severity of a heart murmur in a cat.

Is it absolutely necessary? I have operated on lots of cats with heart murmurs without the benefit of ultrasound exam ( or X-rays or ECGs) prior to surgery. It worries me more when I don't know the severity of the underlying heart disease leading to the murmur but when there is a good reason for surgery and a client can't afford, or won't allow, ultrasound exam first, I will do surgery anyway. Cardiomyopathy, one of the leading causes of heart murmurs in cats is also considered to be one of the leading causes of death during anesthesia, though. So there is good reason to consider ultrasound exam prior to surgery.

The costs associated with diagnosis and treatment of murmurs varies really widely, depending on what the cause of the murmur is.

The earliest I can remember a female cat coming into heat was around 5.5 months of age, but most cats probably wait until seven to nine months of age.

Male cats usually do not start to spray until six months of age, or later.

Heart murmurs in cats are not common but they are not quite rare, either. It is unusual to find four kittens in a row with murmurs. That amounts to really bad luck.

Many of the cats that do have heart murmurs do not experience any problems relating to the murmur. However, there can be serious problems when a murmur is present, so the best approach is to get an ultrasound exam of the heart when it is possible to do so.

Good luck with this.

Mike Richards, DVM 5/4/2000

Heart murmur

Question: I have two questions:

1. My vet said my cat has a heart murmur of about a 3 in intensity. What does this mean in terms of my cat's health? Is this serious? Will it decrease his longevity?

2. My cat sleeps all the time. What is a normal amount of time for a cat to sleep? How can I tell if he is lethargic? And, if he is, what could that mean?


Answer: Julie-

The significance of heart murmurs varies a lot. A heart murmur that is present when a cat is born may be quite loud but of little significance. A heart murmur that was not present when a cat was younger is usually more significant. In general, I think it is a good idea to ask for referral to a veterinary cardiologist, or at least a veterinarian who can do a good job of cardiac ultrasound exam, to discover the significance of a murmur in a cat. This is the best way to determine how important a murmur is in a cat. Most vets use a scale of 1 to 6 to describe the intensity of a murmur. A murmur rated a "1" is usually difficult to detect but the vet is pretty sure it is present. A murmur rated at "6" can be felt by placing a hand on the ribcage over the heart and can be heard without the aid of a stethoscope by placing the ear on or near the chest wall.

Cats sleep a lot. Up to 16 hours a day of sleep is considered to be normal for cats. But they shouldn't be lethargic when they are awake. If your cat isn't curious about what you are doing, doesn't come to check out what is happening when the can opener runs, won't play when it seems like he should, then lethargy is likely. Lethargy or tiring easily, associated with a heart murmur, in a cat, is highly suspicious for cardiomyopathy or an another heart problem that is causing significant problems.

Ask your vet if there is a veterinary cardiologist or veterinary internal medicine specialist in your area who can do a good ultrasound exam of your cat's heart. It really is the best, and sometimes the only, way to tell what is happening in your cat's heart and how significant the problem is.

Mike Richards, DVM 3/8/2000

Heart murmur

Q: Dear Dr. Mike, My male cat of 10 y/o has recently been diagnosed with a heart murmur. For now the vet has prescribe 1/2 bayer aspirin once a week. He is do to return to the doctor's for a visit in one month and from there to be scheduled for an xray and ultrasound. My question is: How common is this? How serious? What can I do to give my cat a long healthy life is spite of his problem?Thank you for immediate response. I am very worried about Charlie and I want to know more about his problem.

A: Heart murmurs are not that uncommon in older cats. It is important to explore them with ultrasound exam whenever possible because of the possibility of cardiomyopathy. Once you have these results it will be a lot easier to decide how (or if) to treat the problem causing the murmur.

Mike Richards, DVM

Last edited 09/17/02


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...