My 3-y-old neutered, female Burmese cat, who has always been very gentle and loving both with me and my other cats has suddenly started attacking my other two cats. This has lasted for about 16 hours at this time. What could be wrong with her?

It could be a territory dispute. How old are the other two cats? If they are younger, she may be feeling like it's time for them to go find their own territories.

It's also possible that it's a classic case of displaced aggression. Is there anything outside that may be upsetting your cat? If your cat is wanting to get out and attack another animal and one of the other cats comes by, the first cat may attack the inside one because it's handy. And some random things can trigger this. There have been cases of cats being startled by their own reflections in glass and attacking a handy cat because of it.

And it could be a sign of a physical problem, so a visit to the vet is not a bad idea.