An abnormal heart sound may affect your cat's lifespan, but from this information it's impossible to know what type of problem is causing the abnormal sound or if it can affect your cat's lifespan.
You should continue to monitor your cat's breathing rate. I was instructed to measure my cat's breathing rate while he was asleep, but check with your vet to ensure that a spike during activity is okay. If your cat has a sustained breathing rate of over 30, you need to take your cat to see a veterinarian immediately.
A sustained high breathing rate can indicate congestive heart failure. Congestive heart failure is a medical emergency, and the cat must immediately be taken to the veterinarian for treatment.
If her breathing rate is generally normal, you can choose to practice watchful waiting or to schedule a cardiologist appointment.
If you choose to see a cardiologist, they will do a full exam that typically includes an echocardiogram. In this test, the cardiologist uses an ultrasound to view the structure of the heart.
The results of the echocardiogram can be used to determine medications that will help prolong your cat's lifespan if the type of heart problem may cause death.
Some types of heart disease can increase the risk of blood clots. The major danger with blood clots is saddle thrombus. The clearest symptoms to look for are
- sudden extreme pain
- sudden paralysis (most often in the hind limbs)
- rapid abnormal breathing rate
A cat experiencing these symptoms must go immediately to the veterinarian. This is a medical emergency.
We were told Hunter had an abnormal sounding heart, and to monitor his breathing rate (watchful waiting). We did, and everything was fine for a few years.
One day (during the weekend, so we were home), he started breathing abnormally fast. We took him to the ER and he was diagnosed with congestive heart failure, hospitalized for a few days to stablize, and then sent home.
If we hadn't been home (if we had been at work, for example), he might have died before we could get him treated. On the other hand, there are lots of reasons for abnormal heart sounds that don't lead to congestive heart failure. Watchful waiting is a risk.
The ER put him on diuretics, which decrease the fluid buildup caused by an ineffective heart. The ER didn't have enough information to treat the actual heart problem.
We took him to a cardiologist, who did an echocardiogram. He diagnosed Hunter with restrictive cardiomyopathy, which is apparently pretty rare in cats. My general vet had only ever seen 1 case before.
We continued to take him for echocardiograms every 3 months, and the cardiologist adjusted his medications each time. In our area the cardiologist's fees are about 5-10 times a normal exam fee. He gave us prescriptions for generic human medications that we could buy from local pharmacies inexpensively when available (we had to cut them into small enough doses). One medication we had to mail order from a compounding pharmacy, but it wasn't much more expensive than the others.
This type of heart disease is characterized by a thickening/hardening of the heart's walls. There's no medications to treat that. They did give us medications to thin the blood and prevent blood clotting (which is common with this type of heart disease).
He was euthanized about 10 months after his congestive heart failure ER visit. I suspect he had a blood clot somewhere critical, but we didn't do any diagnostics to determine exactly where. We were told by the cardiologist to expect him to survive 6-12 months when he was diagnosed, so our experience was exactly in line with the cardiologist's estimate.
Hunter's lifespan was shortened by his abnormal heart sounds. That doesn't mean that your cat's life will be.
Perhaps he would have lived a little longer if he had seen a cardiologist before the congestive heart failure episode, but he declined so rapidly (and there isn't really any treatment for the underlying cause of his problem) that I'm not really sure it would have been worth the trouble or expense.