Dear Siouxsie, Thomas and Dahlia:
Hi there! I love reading your columns and I have a question of my own for once. I have three cats, a mom and her two daughters who are 5 years old. They have all lived together as indoor cats this entire time and they have always gotten along well for the most part. Then this past week, one of the younger ones has started hissing and physically attacking her mother every time they are in the same room together. Nothing has changed in the environment, and they have the run of the house so they are hardly cooped up together. None of them have been in contact with any other animals where they could have picked up a strange scent. So I'm wondering what might trigger this sudden personality change. The mother has always been a tad aggressive, but most days they could still be found lounging together in a sunny spot in the house or grooming each other without a problem. Neither one is acting this way toward the third kitty, who just sits in the corner wondering what the heck is going on! We have to keep them in separate parts of the house right now because it's an all out war when the two get together. Could this be a sign of illness? Or just a phase? I'm a little worried and I'd like to have some peace in the house again. Any advice would be greatly appreciated! Thank you!
~Marie

Siouxsie: Marie, there are a couple of reasons why one cat may suddenly start attacking another one, but barring outside factors such as new scents or strangers in the environment, it's usually about a struggle for rank or territory.

Thomas: Cats are social animals, contrary to some thinking on the subject, and they do get along well together in situations where there is enough physical space and abundant food.

Dahlia: Territory can be a more complicated issue than you might think. We cats divide our territory horizontally and vertically. This means that a bunch of cats can live inside a house as long as there's enough vertical space -- perches on cat trees, chairs, shelves, and other such things -- to give each cat control of an adequate amount of space.

Siouxsie: Dahlia makes a good point, Marie. Although there are no other animals around, have you recently gotten rid of a piece of furniture or a cat tree that was maybe starting to look ragged around the edges? If so, you may have unintentionally reduced one cat's territory, so the aggressor may be looking to conquer a new realm, so to speak.

Thomas: If you haven't removed furniture from your home, you might try adding a vertical element like a floor-to-ceiling cat tree with perches at various heights. You can buy these trees, which stand on the floor and attach at the ceiling by a tension rod (thus requiring no hardware or power tools).

Dahlia: If you or a human housemate is handy with tools, you can build something similar for a lot less money. You can take your cue from commercially sold cat trees and cover the posts and perches with carpet remnants. We prefer low-pile carpet rather than thick shag rugs.

Siouxsie: We're not sure your younger cat's behavior is related to a developmental phase.

Dahlia: Cats reach physical maturity between 8 months and 1 year of age, and this can cause shakeups in the feline hierarchy.

Thomas: Around age 3, cats reach social maturity. This is similar to turning 30 in humans. In cat families, social maturity can cause rank-based conflict. The next major life stage change occurs around 7 or 8 years of age, when cats reach "middle age," and then after cats reach 10 or 11, they reach true senior citizen status. But we don't know of a similar stage that happens at age 5.

Siouxsie: Watch who you're calling old there, buster! I may be going on 11, but I can still kick your flank!

Dahlia: The only flank-kicking I've seen recently is when Thomas came to my rescue when you attacked me for no reason. And I'm still recovering from being spayed! You meanie!

Siouxsie: Don't make me come over there, Shrimpy!

Dahlia: What are you gonna do? Sit on me? Ooh, I'm scared!

Thomas: Dahlia, be nice! Siouxsie is Top Cat, and you need to respect her.

Siouxsie: I am so above your petty, juvenile antics. Humph!

Thomas: Anyway, Marie, if your cats aren't having a territory or life stage issue, they may be having a rank issue. The aggressive cat may have sensed an opportunity to move up in the feline hierarchy. As the top cat -- in this case, your mama-cat -- ages, she may become weaker and less agile.

Siouxsie: Of course, I'm just as strong as ever, so don't even try to usurp my Top Cat rank!

Thomas: You're right in thinking the sudden aggression may signal illness. Your mama-cat may be in the very early stages of an age-related condition. This wouldn't be obvious to you, because we cats instinctively hide our illness or pain. But it would be more obvious to a younger cat with aspirations to move up the hierarchy.

Dahlia: For this reason, we think it would be a good idea to contact your veterinarian and ask what he or she thinks. It may be a case where you're asked to monitor the older cat and make sure her eating, drinking and elimination habits are normal. Or you may be asked to bring the mama-cat (or maybe even both cats) in for a checkup.

Siouxsie: You might try Feliway diffusers in the room or rooms where your cats like to hang out. Feliway is a product that mimics the pheromones we cats produce in glands on our faces.

Thomas: Marie, I'm sure you've seen cats bump and rub their heads on things. We do that when we're calm and happy, and we leave these "happy cat" pheromones wherever we rub. Feliway works like head-rubs in that it leaves these happy pheromones in the air. It works very well at sorting out territorial stress between cats, as well as urination or spraying problems. Mama's used it with us before, and I can tell you from experience that it's good stuff!

Dahlia: Was that the stuff Mommy sprayed around when she brought me home? That was nice! I felt all happy and stuff when I stepped out of the carrier.

Thomas: Yes, Dahlia, it was. Feliway comes in a spray as well as a diffuser, but I think that in Marie's situation, the diffuser would work best.

Siouxsie: So, Marie, we hope we've been able to give you a few ideas about how to deal with your fighting felines. Do talk to your vet about mama-cat and the sudden aggression situation, just in case it is a sign of illness. Adding more vertical space and using Feliway might also help restore calm to your home.

Thomas: If things don't calm down with these tactics, you may have to reintroduce them as if you were bringing a stranger cat into your home. We've written several columns about introducing a new cat, and these will be of help if you need to go to this extreme step.

Dahlia: And, of course, The Paws and Effect Guide to Introducing a New Cat is available for a mere $3.00. Visit the Paws and Effect merchandise page for more information about that.

Siouxsie: Good luck, Marie. Please let us know how it goes.

Got a question? Need some advice? E-mail us at advice@paws-and-effect.com. None of the material in this column is meant to be a substitute for regular veterinary care.