My male cat has went into heat after getting fixed

Question
my male cat seems to have gone into heat after he and my other female cat got fixed and for some odd reason he seems to wanna hump her and i dont understand that. i'm very confused because he's never done that to her. we got them both fixed yesterday

Answer
Caitlin,

The term 'in heat' refers to estrus cycles experienced by sexually mature female animals that aren't spayed. Being in heat simply means that the female animal is receptive to breeding. Male cats don't have heat cycles and can mate at any time with a number of female cats in any given day. Neutering an intact male cat doesn't necessarily mean that he will immediately stop behaviors like mounting other pets, using urine or feces to mark his territory or even fighting with other intact cats in the neighborhood if he's allowed outside. If your male cat was fully mature when you had him neutered it's very possible that his testosterone (male sex hormone) levels need some time to drop down after his castration. It's likely that your male cat will settle down within the next few weeks and stop mounting your other cat if he's being motivated by testosterone in his blood stream. I would expect that your cat will settle down once he's been home for awhile and his hormone levels drop down.

Mounting another cat can sometimes be a way of showing dominance. It's possible that your male cat senses that his sister is feeling a bit less feisty than usual and he's trying to take advantage of her vulnerability. It's not a good idea for the female cat to get riled up or be picked on so soon after her spay because that's a major surgery. For now I'd suggest that you ignore the mounting behavior or make sure to apply consistent humane discipline to get your point across. If you'd like to convey the message that your cat is out of line you can squirt him with a stream of water from a spray bottle or water pistol. It's very important to avoid getting your female cat's spay incision wet - it needs to be kept clean and dry to avoid a potentially serious infection so do be careful if you're spraying the male cat for mounting the female or getting rough with her. Most cats aren't fond of getting wet and having their coats messed up and they'll often go and sulk in a corner for awhile to dry off. Shaker cans are easy to make and often effective, however they're noisy and can't be used at night if you live in an apartment. You simply put a few dried beans or pennies into a pop can, tape it closed at the opening and you have a shaker can. You can use the shaker can to startle your cat when he's getting out of hand. You could also opt to use a can of compressed air which makes a hissing sound that most cats understand immediately as a warning. It's very important that you don't aim the can of compressed air at the cat's face or body and of course avoid shaking the can or turning it upside down as this can cause the contents to become quite cold. If you notice that using humane deterrents fails to settle your male cat it's not a bad idea to consider setting your female cat up in a quiet room with all of her necessities so that she can recuperate from her surgery in peace. Your vet will want to ensure that she's healthy and free of infection after surgery and many vets schedule a follow up visit a week or two after spaying a cat so that they can check up on how the little girl is healing. If your male cat is still acting up when you take your female cat in for her follow up vet visit I'd recommend mentioning the behavioral issue to your vet and asking what the best course of action is if using humane deterrents like squirt bottles, shaker cans or compressed air don't work.