Q: Will it be harmful to my female cat if she isn’t mated after calling?

Answer: Well, cats that that go on calling without being mated can develop fluid-filled cysts on their ovaries which produce sufficient female hormone to interfere with normal oestrous cycles and ovulation, and with the implantation of the fertilized egg in the uterus. Therefore these changes can be the cause of infertility. At present it isn’t clear whether inducing pseudo-pregnancy will serve as effectively as pregnancy in preventing this occurring. It is, of course, psychologically distressing for the cat to be continually calling if you don’t intend to let her have kittens.