Are there any risks in spaying a bitch with a heart murmur? When we adopted Katy, her foster parents said the vet had found a mild murmur when she had her last mange treatment. They said puppies often grow out of them, so I didn't think much about it. I don't even really know a great deal about them. I had planned to let her have one season, then spayed 3 months afterwards. However I just read something about a cat not able to be spayed because of a heart murmur. Little bit worried now. It's not been checked since, as we're no where near the vet and I don't really like going unless we really have to, so I thought I'd have it checked before her spay.