Both castration in the male cat and spaying in the female are major operations which need a general anaesthetic. Your cat must be starved overnight before the operation to reduce the risk of problems on the operating table. However, there is very little chance of anything going wrong, it is one of the operations most frequently carried out by vets and any experienced vet will have done it many hundreds of times.

In the female the operation involves opening your cat's belly to remove the ovaries and uterus (womb). Your cat should be ready to come home on the same day as surgery, as soon as the anaesthetic has worn off. If there are any complications, your vet might want to keep your cat in hospital overnight to keep an eye on them. The fur where your cat was shaved for its operation may re-grow slightly darker than the rest of its body but the contrast often disappears after the next time your cat moults its fur.