I have two male cats age 7 years old who I purchased from a local pet food store when they were 6 weeks old. They have been friendly with each other for these seven years, eating, playing, always sleeping together until 3 months ago when something happened during the wee hours in the AM.

They have been indoor cats since we purchased them. They are completely at odds with each other now, hissing, etc. I have them separated in two locations of my home, which was suggested by my vet. I have been giving Prozac to them per my vet.

I do not want to let them fight it out because one is 24lbs & the other 12lbs. They were both spayed. A female cat is also in my home, which they have no problem with. I have had many cats in my lifetime that all lived together with no problems.

I am completely perplexed at this problem. I wonder if they will ever be friendly to each other again. Both are friendly with people. Do cats ever forget things that would upset them, or do cats have mental breakdowns or go insane?

Thank you for any answers or suggestions.

  • 1
    take them to a vet to see if any of them are having any pain as this might be the reason for agression,i myself gets a little unfriendly when i am in pain. Commented Jun 13, 2017 at 5:52
  • Thank you for the reply. My vet had made a visit to my home & checked both male brother cats out. He did not see a problem. He thinks that Sir Rhett Sir the 24 lb brother was spooked by something that early morning & his brother Tommy Jean the 12lb one just happened to be there at the moment. I leave the curtain up on one of my French Doors so they can look into my yard. In . Who knows what happened. There was pee & poop on the wood floor. What ever happened Sir Rhett Sir got really upset! Perhaps the dogs next door got loose or the cotoye seen in our area that week!
    – Patsy
    Commented Jun 14, 2017 at 12:32

3 Answers 3


I have had cats go through this every now and then. It sounds like they are just having a prolonged feud. If this is the case the situation is fixable.

This behavior can also be caused by jealousy. If one cat receives more affection than the other the, the other cat may retaliate and start a fight. Start off by preventing jealousy fights by making sure they both get equal treatment and plenty of affection.

Right now your cats associate bad feelings with each other. You need to reverse this by having them associate good feelings with one another.

To do this you need to praise and reward them whenever they are peacefully interacting, or even ignoring each other. Pet them, verbally praise them and give them cat treats.

Cats identify each other by smell, so you want them to associate good things with each others' scent. Pick one cat and pet the sides of his face and head profusely where there are a lot of scent glands. Then with your scented-up hand pet and praise the other cat. Do this both ways so the cats associate each other's scents with good feelings (affection and praise). Do this several times a day for at least a week. Then do this periodically as maintenance.

If they eat side by side, this is an excellent time to pet them both and praise them.

Also you want to discourage / punish bad behavior such as hissing at each other. Scold them by raising your voice as soon as they begin hissing or growling at each other. You can also shoo away the aggressor. As long as you know they won't attack you when agitated you can also gently scruff the aggressor (holding them down for about 5 to 10 seconds) to let them know you don't approve of their behavior. You are trying to scruff / restrain them not actually cause them pain so be gentle.

Reward their good behaviour, discourage the bad, and your cats should learn to get along better in a week or so.


I will try to give some sort of an answer for at least parts of your question.

Of all animals, a cat's short term memory is probably better then the long term memory of elephants, (this is taking it a little far, but my point is, cats have a really good memory). http://pets.thenest.com/cats-longterm-memory-8646.html

Cats can get senile when they get old, but a 7-year-old cat is normally not senile.

Cats don't normally have mental breakdowns or go insane, but I have seen a kitten that I do believe actually was mentally ill, I did take care of my sister's cat during her vacation. This cat had kittens about 2 months before this (my sister's cat was my cat's sibling, both female). The problem was really hard for both the adult cats. https://www.vetinfo.com/signs-mentally-ill-cat.html


Unless there have been some changes in the environment I can't explain why your cats can't get along.

A cat that is not well might sometimes get aggressive, but the normal thing is that the cat wants to be left alone.

Cats can get depressed if their owner dies (I have seen this when my mother passed away and I was left to take care of the cat.) Cats can also get depressed if their cat friend dies (I have seen this when my old cat died and I was left with the cat I got from my now dead mother). All of this happened within two years.

Keeping the cats separated doesn't solve the problem in the long term, as you know.

Sorry for not being able to help you with the problem.

  • Thank you for your comments. My vet came to my home & checked both brothers out, nothing of sickness showed. He thinks Sir Rhett Sir, the 24 lb bother was spooked by something that early am & his bother Tommy Jean the 12 lb one just happened to be there. I leave the curtain open on one of my French doors. They look into the yard. Maybe saw a wild animal. Coyote in neighborhood that week, dogs next door sometimes get loose. Pee & poop on wood floor. What ever it was Sir Rhett Sir really got spooked!
    – Patsy
    Commented Jun 14, 2017 at 12:37
  • cats can get scared but i have hard to belive that this is the reason for the fighting,my cats are outdoor cats and they can get scared by foxes dogs lynx and every other thing that lives here,but this only results in my cats beeing afraid for a very short time,i am talking minutes not days. Commented Jun 14, 2017 at 17:05

Let them fight it out.

If they're having a dominance struggle, your intervention is only pushing that problem further into the future, rather than letting them resolve it themselves. Only intervene if they're really going at it and there's a threat of injury. Otherwise, let cats be cats and let them sort out their problems in their own way, without human intervention.

  • 2
    Thank you so much for an answer. Sir Rhett Sir 24lbs & brother Tommy Jean 12lbs. I thought about letting them fight it out -kind of scared difference in size. small brother not a shy cat. have another female 7 years purchased same time & has been living with them since. There is no trouble with her. Fighting is between the brothers. I think I am going to let them get together when we are home just to see what will happen. Poor Sir Rhett has been in downstairs area for 2 months purchased a Thunder Shirt for Sir Rhett calming effects. cat person. Prozac good 4 hrs Perplexed!!
    – Patsy
    Commented Jun 14, 2017 at 12:58
  • 1
    i dont think this is a good advice as both cats will get seriously hurt possibly even killed. Commented Jun 14, 2017 at 17:17
  • @trondhansen I covered that in my answer: "intervene if they're really going at it and there's a threat of injury."
    – sleddog
    Commented Jun 14, 2017 at 19:05
  • 1
    i have tried to stop cats from fighting it did not end well. Commented Jun 14, 2017 at 19:35

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