4yo cat's behavior changed

My 4yo cat has recently undergone a drastic change in personality. I moved in with my girlfriend a few months ago and she also has a cat. The two of them got along very well (my cat constantly followed hers around licking him, and they played often), but recently my cat has become very grumpy and growls at her cat. This has been going on for over a month, but we have been here almost 8 months now.

This change came along with an increase in weight from my cat, and I am wondering if the increased lethargy could cause a change like that. We recently switched their food to one that is more suited for indoor cats, so hopefully she will lose a little weight.

Take the cat in for a check up. Sudden personality issues and weight gain can be signs of many disorders. They are very good at hiding illness especially things like diabetes. Once you rule it out illness you can look to other sources. I had a pair of siblings that were stuck like glue together for years and then one day they just hated each other. Went on for about 6 years that way. I figured its like people, we can be fickle and hold grudges forever, why should animals be different.

Fortunately my cat is still affectionate towards the people. I am hoping she is just being fickle, but we have changed the food we are feeding them so maybe it was a reaction to what she was eating. The other cat has not gained any weight, but he is young and hyperactive.

Also, when she was thinner we were actually feeding her a small amount of canned food every night. Maybe I should start her on that again.

Your cat reminds me too much of others I've known in similar circumstances and I strongly suggest you take her to the vet as soon as possible.

I agree...sounds like a sign of a health issue. It's best to take her in to see a vet, and find out nothing's wrong, than to not take her, have something be wrong, and lose her just because you didn't take her in.

Hugs to you both,

Rosie*