Help! My Old Cat Harasses My New Cat.

Question:
I have a cat that I have had for 7 1/2 years. (since he was 6 weeks old) 4 months ago I got another kitty about 1 year old. The older kitty will chase the new one under the chair and sometimes run up to her and slap her. He will also catch her in the litter box and won't let her out of it. I have 2 litter boxes, but it doesn't matter which one she uses, he acts the same. Please advise if there is any way to break him of these actions. Any suggestions would be appreciated.

A:  I would recommend a consultation with your veterinarian for medical intervention if things do not improve.

What you are describing is a territorial behavior in the older cat.  Both indoor and outdoor cats are surprisingly territorial and work very hard to protect their territory.  Your older cat is protecting his territory from the younger cat by bullying her into corners and other places.  Breaking up the arguments will most likely make things worse.

I would recommend speaking to your veterinarian about some medical intervention if the two cats continue to have problems.  Either an anti-anxiety medication or a progesterone supplement can be used to try to curb this behavior. 

Unfortunately, there really isn't a good straight-forward answer to this dilemma.  If the trouble continues, I would recommend consulting with your veterinarian about the medical options available for your cat.

~Dr. Page Wages
Oberlin Animal Hospital