heart murmurs
Hi Kitkat, yes I have had quite a bit of experience with heart murmurs.
I picked up a lot of heart murmurs in cats when I was in a full-time feline practice. I have a really good stethoscope, so I heard a lot more than most other vets, based on guardians saying "no, nobody ever said she had a murmur before" when I would find one.
In young kittens, most murmurs will go away over time as the heart develops and matures. However, they should be rechecked after 6 months of age to be sure.
Quite a few murmurs are stress-related; when the cat is relaxed, they disappear. I remember one cat, a very tense tabby about 4-5 years old, who not only had a murmur but also really awful arrhythmia (irregular heart rate). It was so bad, I thought she might drop dead even if I sent her directly to the cardiologist. The guardian happened to mention that the cat just *loved* riding in the car...so on a hunch, I told her to go drive the cat around the block. When she came back, I climbed into the car and listened to the cat's heart again. It was absolutely normal. Big lesson learned for me! Since then I noticed that a lot of cats who had a murmur on exam, didn't have one under anesthesia.
Some murmurs are "innocent," a result of a slight functional abnormality that does not affect the cat and will not progress or become problematic.
However, other murmurs are pathological, either the result of underlying heart disease, or causing increasing dysfunction.
My policy has always been to recommend a cardiac workup to distinguish which type of murmur it is. These are not cheap, but the knowledge gained is very worthwhile, IMHO at least.
In the case of pathologic murmurs, if they are caught early, they can be successfully treated. Once a cat shows symptoms of heart failure, the disease is usually very advanced and their prognosis is very poor--they survive less than 6 months at best, but often only a matter of weeks.
If the murmur is innocent, you've spent a bundle, but you've also bought yourself considerable peace of mind. If the cat ever needed surgery, especially in an emergency, you would feel a lot better knowing that the heart is really fine.
I'd estimate that, of cats who were taken in for a cardiac workup, about half had innocent murmurs, and half were associated with heart disease.
So that's my story on heart murmurs, and I'm sticking to it!
Cheers,
Dr. Jean