Life with multiple cats can be great: lots of purrs, more snuggles, and cats that may keep each other entertained. However, even if your cats have gotten along historically things can change quickly.
You may or may not have witnessed the triggering event or the first fight. Heck, in some cases it may not have been something you would have thought would have caused problems between the cats.
One common scenario goes like this: Two cats who have live together for years in blissful feline harmony. One day, one of the cats goes to the veterinarian for a routine check up, a dental procedure, or needs to see the vet for any number of reasons. Upon their return, they're acting a little off, but that's understandable. The vet can be stressful! (But regular trips to the veterinarian are absolutely necessary!)
The cats may be fine with each other for a while or something may happen right away, but eventually a fight breaks out. In that moment, the cats' relationship is broken. The cats, who previously would lounge and play together, can't be in the same room with each other without there being conflict. Even if the cats can be in the room with each other, they may seem more stressed than usual and don't quite seem the same.
When cats who previously got along seem more like enemies, it can be extremely tough on the humans, too. You just want to see your sweet cats be buddies again and not have to worry about if one will claw at the other cat just for existing. Will life ever be the same?
While the reasons for cats fighting varies, in the situation described above the reasoning is because the cats don't recognize each other. This may seem odd to us, but smell is a huge influence on how cats recognize each other. If one cat returns from the vet smelling and acting differently, the other cat may see them as different enough to think they are an unfamiliar cat.
Cats are extremely territorial and unfamiliar cats are often met with suspicion and hostility. One cat, understandably afraid because there is now a threat in their territory, moves to defend themselves. The other cat, who may have recognized their buddy, now feels threatened and becomes frightened whenever they see their former friend.
When this happens, you'll probably want to return your home to normal as quickly as possible. Unfortunately, these situations often require time to resolve. In order to get the cats back to being friends again, you'll need to go through a process called a reintroduction.
Reintroductions are ways of teaching each cat that the other cat is not only not a threat, but that good things happen when the other cat is around! The process is often successful if done correctly, but it can take months in many cases to get things back to somewhat normal. It also can become more difficult the more negative interactions the cats have. In some cases, it may not be resolvable.
Because the process is so long and taxing on the humans, doing it alone can be tough even if you follow a reliable guide. Fortunately, I'm very experienced with going through this process! Reintroductions are, without question, the most common reason I am contacted to help folks out. The process can be long, take an emotional toll, and be done wrong if you aren't sure what to do.
Because every negative interaction between the cats can make the negative association with each other worse, it's important to prevent negative interactions as much as possible. If you want to make sure your cats get properly reintroduced, Class Act Cats has developed a special reintroduction program specifically for these situations. We'll work together through the whole process to get the fighting stopped!
About the author: Joey Lusvardi CCBC is a Certified Cat Behavior Consultant and cat trainer based out of Minneapolis, Minnesota. He runs a behavior consultation service, Class Act Cats, where he helps cat parents address a variety of unwanted behaviors. He is available for consultation in the Twin Cities or virtually wherever you are located.