# Sudden Aggressive Behavior



## mrszeeky (Nov 28, 2010)

We have 3 sibling cats that have been together since birth and have always been best friends == 1 male and 2 female, spayed, neutered and declawed front only and they are indoor cats. We go on mini trips often and leave them for up to 4 days on their own and have had no behavioral problems ever. We went away overnight for Thanksgiving and upon return observed aggressive behavior by the smaller female towards the male (catfight). This catfight is now 3 days running and not resolving itself. We think maybe a stray cat is showing up and confronting them visually through the sliding glass door and causing the outbursts but we are not positive. What could cause such a drastic change in behavior in the smaller female being hostile to her brother. Any ideas??????????


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## catloverami (Jul 5, 2010)

It's impossible to know what caused it since you weren't there to observe. It's possible it was a cat outside the patio doors that resulted in redirected aggression, but you'll never know. I would not leave my cats alone for that long, even for a day. You just never know what may happen.


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## Jan Rebecca (Oct 14, 2010)

Oh no - I hope it is resolved soon.


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## doodlebug (May 13, 2006)

mrszeeky said:


> We think maybe a stray cat is showing up


Definitely the most likely explanation...it's called redirected (or misdirected) aggression. Google it and you'll find tons of articles.


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## Susan (Mar 29, 2010)

I can only think of three possible reasons that would result in sudden aggression. The first is the one you suggested...redirected aggression to a stray cat. The second is territorial aggression, which usually starts to rear its head when the cats reach social maturity, at or around the age of 2 (not sure how old your cats are). The third possibility is medical. Certain illnesses can cause aggression; alternatively, cats who are in pain (even from something like dental pain) can become aggressive. Perhaps there are other possible explanations, but none that I can think of. Whatever the reason, this sort of thing could have just as easily happened when you were out shopping for the afternoon, so don't blame yourself for leaving them overnight. 

I would tend to first rule out medical causes for any sudden changes in behavior. If the cause is not medical, then I would suggest you do a short re-introduction of the two cats in question...and it would be best to do so in the near term, before the aggression escalates any further.


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## catloverami (Jul 5, 2010)

I should have expanded on "just never know what may happen". If a cat developed a urinary blockage and was unable to pee, it would be a vet emergency, and a cat could die in that time. Often times cats will be stressed if the owner is away, and somtimes that can bring on a urinary problem.


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## mrszeeky (Nov 28, 2010)

Thank you all. The cat in question is going to the vet tomorrow to check out a medical cause.


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## Susan (Mar 29, 2010)

Good luck...keep us posted.


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## mrszeeky (Nov 28, 2010)

Went to the vet and cat is healthy. She prescribed prozac. Does anyone think it is possible that now the other cat has become aggressive too? I found him this morning cornering Sammy. We are thinking about taking him to vet also. Any thoughts?


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## Susan (Mar 29, 2010)

I don't suppose it could hurt to have him checked out, but chances are that he's reacting to the aggression of your female. The most common approach to dealing with cats that have become aggressive (where there's no medical cause for the aggression) is to do a short re-introduction of the two cats (or a longer re-introduction if the aggression is relatively severe). You might try that before moving to the prozac. Perhaps the following link will help: ASPCA - Virtual Pet Behaviorist - Aggression Between Cats in Your Household


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