Nonrecognition Aggression

Hi all,

So I have 2 cats, and they have lived peacefully/happily together for 6 years. My older cat is a medium/long hair and she was having troubles keeping her fur from matting & cannot stand being brushed so last year we made the decision to have her shaved. I took her to a professional groomer & when I brought her back my younger, much larger, male cat flipped out & didn't recognize her. He was extremely aggressive & attacked her constantly. We had to separate them & I tried all the methods of rubbing scents all over each other & nothing seemed to work. All the sites I go to say that non-recognition aggression stops within a few days but it took MONTHS for them to be able to be in the same room together. I thought we had it under control & they were finally sleeping together again when we made the decision to shave her again (once a year). This time I didn't take her to the groomer and just shaved her at home so that she didn't smell any different than normal, just look a bit different, but it didn't matter, our younger cat immediately started attacking her again. It has now been almost 2 months since we shaved her and they are still aggressive to each other. As soon as one spots the other in the house there is immediate growling, hissing, and posturing, and if they can't get away from each other it turns into a big fight. And a big problem with the fighting is also that our older female cat is declawed, but our much larger male cat is not, so it is a one-sided fist fight.

I'm not sure what to do to help them get along. Is this really non-recognition aggression? If so, why wouldn't it stop after a few days? I don't want to get rid of either of my cats since I love them both dearly but I also don't want to have them living in fear in their own home. It is almost like he doesn't recognize her until her hair starts to grow out a bit and she looks more like normal.

Also, side note, they are both neutered/spayed and when I got our younger cat 6 years ago he was a kitten so they have lived together for basically his entire life without any issues.

Just because cats recognize each other in part of by scent doesn't mean that visual stuff doesn't play into it. Maybe a visual change isn't a huge deal for some cats, but for yours it is or was.

Also keep in mind that if cats fight and hurt each other, the original non-recognition aggression is no longer the problem; it is the memory of being hurt.

Have you tried a full reintroduction process? That should work. Long term, your going to have to fine another solution to the hair problem.

Hi. I think A ArtNJ might be right about reintroductions. The TCS article on non-recognition aggression does state that it might be necessary to separate them completely and then go through the full introduction routine - which a link for the process is included in the article below.

How To Deal With Non-recognition Aggression In Cats

You might want to look into options that would allow you to at least partially avoid the matting - something you can do on a more frequent basis, so it is less of a drastic change to her appearance. I know nothing about products like the Furminator, but maybe looking into items like that would be an option to try?