Help - Formerly Friendly Males Suddenly Not!

[GillieGirl]

I have two male cats, Duncan and Finley, both 3 years old, spayed, and friendly. They were adopted on the same day from the same shelter. Since I've had them, they've acted like brothers. They sleep, eat and play together. Sometimes the play is rambunctious with one stopping with a hiss but that's the end of it. Otherwise there have been no issues whatsoever with these two buddies.
Suddenly today, it's like Finley doesn't recognize Duncan. Finley has been prowling, howling, tail all poofed out....pretty much stalking Duncan and acting like he's never seen him before. At one point, Duncan hid under the bed and I thought it was the end of it. Three hours later they met in the kitchen, sniffed one another nose-to-nose, and Duncan hissed and Finley started his growling/low-howling again, following Duncan around.
I thought maybe something was wrong with Finley but aside from being horrible to Duncan, he's acting his usual self with me. What the heck happened to my boys?!

 

[FeebysOwner]

There are cats who can sense illness in another cat due to scent changes, and other cats who are ill that will lash out at another cat. If one cat is on a new medication, that might trigger the same response as that can change a cat's scent as well. Other than that, if one went outside and got into something that made him smell differently, that too can cause a non-recognition type of aggression. The other common thing is when one of the cats goes to the vet and then comes home smelling strangely to the cat(s) that stayed home.

If it is not illness related, a simple solution may be to rub a towel on the aggressive cat and then use that same towel on the 'attackee' so they smell more alike. Most of the time, this will pass in a couple-three days.
How To Deal With Non-recognition Aggression In Cats - TheCatSite

 

[GillieGirl]

Thank you so very much - I've had cats my whole life and have never seen this type of behavior before. Neither has been outside because they are indoor cats and both have been inside. Heading to do the towel trick now. The odd thing is that the attacker is not the alpha cat which makes this all the more puzzling to me. Hopefully this works and I really really appreciate the information and fast response.

 

[GillieGirl]

I wanted to follow up on the great information you gave me yesterday. I rubbed a towel on the attacker and then rubbed it all over my other cat. By early evening, the yowling had stopped. This morning they are both acting as if nothing happened yesterday. So grateful for the information you shared!! My cats can be quirky but they certainly have never behaved like this before!

There are cats who can sense illness in another cat due to scent changes, and other cats who are ill that will lash out at another cat. If one cat is on a new medication, that might trigger the same response as that can change a cat's scent as well. Other than that, if one went outside and got into something that made him smell differently, that too can cause a non-recognition type of aggression. The other common thing is when one of the cats goes to the vet and then comes home smelling strangely to the cat(s) that stayed home.

If it is not illness related, a simple solution may be to rub a towel on the aggressive cat and then use that same towel on the 'attackee' so they smell more alike. Most of the time, this will pass in a couple-three days.
How To Deal With Non-recognition Aggression In Cats - TheCatSite