My cats are growling at each other after neutering. What to do?

Thank you for submitting your question regarding your cats. I suspect that the carrier ride and the surgery were stressful experiences for both cats. This can cause a cat to act out aggressively. You may want to keep the cats separate from each other for a few days to let them calm down. Then re-introduce them slowly and only when they can be fully supervised. Things should go back to normal between them, but it may take some time. I hope this information helps!

Thanks for using Petco Pet Education Center, formerly Petcoach! On the whole, I’m not worried about this yet. It can take a couple weeks to feel completely normal after a neuter, especially in adult males. If you have pain medication still, go ahead and give it as even mild pain can cause some cats to be a little crankier than usual. Sometimes, a long trip to the vet or anesthesia seems to disturb cat relations and anxiety is more of a problem. If this behavior is not improving with pain medication, or persists for another week or more, consider these anxiety-reducing home helps. -Feliway- calming cat pheromone- comes in many forms from pet stores or online. 

- Adding a litter box. Studies show that the ideal number of litter boxes for a home is #of cats +1 . This is regardless of how clean you keep his current litter box.

 -making sure he has plenty of “high space”. The safest (and therefore least anxiety-inducing) place for a cat is up. If you don’t already, get a cat tree or put up a shelf or two that he can go perch on. Best wishes to you and Gus!

It can take several weeks for testosterone levels to decrease after neutering. Until then, consider using a pheromone product, such as Feliway spray or plug in diffuser, to decrease any anxiety or aggression in the home. Provide extra litter boxes, bowls, toys and bedding to prevent food aggression or resource protection.

You should have him checked, or rechecked, by your veterinarian. Neutering typically does not result in more aggressive behavior. Additionally, any sudden behavioral change can be due to illness or injury. Once medical causes have been ruled out, you can focus on behavioral issues. Consider a pheromone product, such as Feliway Spray or plug in diffusers, to help decrease anxiety or aggression. Provide additional litterboxes, bowls, toys and bedding to prevent resource protection. You may have to separate them for a week or two then gradually reintroduce them while employing the measures described above.

It sounds like he is still experiencing some pain. Talk to the vet who did the neuter about prescribing an anti-inflammatory/pain medication to help relieve the pain and make him more comfortable. Do not give any human pain medications as they can be toxic to cats.

It could be that she smells differently now that she had kittens, and Homer views her as a stranger. There is a method you can use to help them get along again. I would separate the cats, and slowly reintroduce them to each other. Take Homer aggressive, and put him in his own room with his own food, water, and litter box. Keep the door closed, and for a few days, feed them both treats on other side of door so they associate each other's smell with a good experience. Then let the other cat in Homer's room while he is in a cat carrier. They can smell each other, but not be in contact. If either becomes upset or show signs of aggression, remove the second cat from the room, and try again later. Praise them when they interact appropriately. When they are interacting well with each other through the carrier, you can let Homer out of his room, and see how he interacts with the other cat. Praise them when they interact appropriately, and separate them with any sign of aggression or upset. I would get a cat tree with lots of shelves to give the cats vertical space to get away from each other. I would keep Homer in his room when you go out until they are comfortable with each other.

Any change at all can make a kitty restless. He will just have to get used to the new room, the new cat and also his body has to adjust to the new situation (no more testosterone). This should subside soon. Restlessness by itself is not a problem, but if he does not calm down back to his normal self you may want to have him examined by a veterinarian.