The condition known as feline heart murmur can be the result of a serious heart condition, but that is not always the case. If your cat has been diagnosed with a heart murmur, you'll need to get confirmation of the cause.
Once the murmur, and it's cause, are confirmed, you'll be able to better decide on treatment options. Veterinarians typically will declare the intensity of a murmur using a scale of 1 through 6, with 6 being the worst murmur.
Cats can have heart murmurs for many reasons, and it is important to get to the root cause. You should know that cats can have murmurs as kittens that eventually go away, or have little impact on the overall health of the cat.
You should also know that some cats can develop murmurs as adults, with no other apparent medical problem. So, even though there may be no obvious signs of illness, the murmur may exist. If the murmur doesn't get any worse, and no other disease is detectable, it's possible that a cat could live out a normal life unaffected by the condition.
Most veterinarians agree, however, that the most common cause of feline heart murmur is a serious heart condition of some sort. Heart disease in cats may take one of several forms. There may also be underlying conditions related to thyroid and/or high blood pressure issues.
Many experts believe that diet and environment are responsible for many cat illnesses, especially when it comes to the health of elderly cats. Overweight cats (obesity in house cats is at epidemic proportions) and those with other medical conditions may be more severely affected by any medical problem.
If thyroid problems are involved in generating feline heart problems, and the environment or commercial cat food is to blame, then this condition will become more common until we fix whatever chemicals are causing the problem.
Note that your cat may have any or all of the related underlying conditions and not have any apparent symptoms at all. In some cases, the first indication that there is a problem is a heart attack resulting in death.
My vet told me about another patient he had. A two year old Siamese cat, seemingly healthy, jumped behind the couch and didn't come back out. She had died of a heart attack. A necropsy was done and it was found that chambers in her heart were a fraction of normal size. She had never shown any signs of illness.
A heart murmur in a cat and the underlying cause is best diagnosed by a specialist. Once your vet detects a heart murmur via stethoscope, a blood test will often be ordered to determine if hyperthyroidism is present.
Typically, either a veterinary cardiologist, and or an internal medicine specialist should be consulted. The best diagnostic tool is an ultrasound (echo cardiogram), used to determine what, if any, structural damage exists in the heart.
Pursuing a diagnosis of feline heart murmur may result in a finding of cardiomyopathy. Cardiomyopathy is, simply put, a disease of the heart muscle. Various forms of cardiomyopathy exist, and there are various associated and underlying conditions (including hyperthyroidism).
Again, an ultrasound of the heart muscle performed by an expert is the best way to confirm the heart condition. Blood tests will confirm the thyroid problem.
This was the case when my oldest cat, Priscilla, was diagnosed with feline hypertrophic cardiomyopathy. She had been to the vet every year and never showed a murmur.
The day she was scheduled for a dental cleaning, she fell off the couch right in front of me. She landed on the floor on her side and quickly recovered, with no apparent injury. I took her in to see the vet, but the vet couldn't find anything wrong with her.
Just in case, though, we decided that the cleaning was going to have to wait. She was almost 11 years old at the time, and had already had pre-appointment blood tests which showed no problems.
We decided to reschedule the cleaning a few weeks out. When I brought her back for the cleaning, this time the vet found a murmur. Follow up blood tests indicated mild hyperthyroidism.
We visited a feline internal medicine specialist, and an echo cardiogram confirmed that she did in fact have hypertrophic cardiomyopathy, along with her minor hyperthyroid condition.