Sudden cat-on-cat aggression

Sorry if this is a repeat story, I did a search and didn't find another post that looked similar to my situation, so I figured I'd give it a shot.

I have two cats, Tasuki (4 year old male, fixed but not declawed, social and cuddly) and Arwen (2 year old female, fixed but not declawed, shy but loving) who get along great (or so I thought). We moved into a new house six months ago and both adjusted to the change well. But Tasuki has suddenly taken to attacking Arwen over the past two months or so. We took both cats to the vet when "bumps" started showing up on Arwen's back and side, and the vet told us that they were puncture wounds caused by Tasuki attacking her, and Tasuki was (and is) in perfect health. We have never witnessed or heard the two cats fighting (they would chase each other around the house, but never was there any hissing, spitting, growling, yowling or physical altercations), so we found it hard to believe, but we kept an eye on them, yet never saw any evidence of this fighting.

Now, a month and a half after that, Arwen is currently at the vet's being treated for a serious skin infection due to more wounds apparently inflicted by Tasuki and Tasuki is temporarily staying with my mother so Arwen can come home tomorrow and heal from her infection in peace and safety.

The question is: Why is Tasuki suddenly attacking her? He shows no aggression towards me or my husband, and according to the vet, there's nothing wrong with him, and up until now, Arwen has also been perfectly healthy. The cats have lived together just fine until he started doing this, the only thing that's changed since we have moved is that I've become pregnant. I've read some articles on feline aggression, but none of them mention a male cat suddenly becoming protective of his "females" (the vet suggested that perhaps Tasuki identifies me as his female and Tasuki can smell that my pheromones have changed due to the pregnancy, so perhaps he's trying to keep Arwen away from me, but the vet also readily said that he's not an animal behaviorist, so that could be false). I'm only 19 weeks along right now, so the timeline for when Tasuki started this behavior does seem to fit if the pregnancy is what's setting him off. Has anyone else heard of anything like this?

I know I'll have to keep the cats separated until Arwen has a chance to fully heal from the infection...is it too much to hope that I can have my happy homelife, complete with two loving kitties who don't fight, back after she's okay and Tasuki is reintroduced to her? Any advice is much appreciated. I love both my cats very much and I don't even want to entertain the thought of possibly giving one cat a different home as a solution to this problem.

First of all, just stay calm. This can work out, but it does require some detective work on your part. You have to figure out what has changed in the home to cause these attacks? Sometimes, someone is pregnant. It could be that there is a cat outside instigating these attacks by spraying your home (outside). Sometimes, it is just a matter of a simple change, no matter how minute that can trigger a cat to aggression. Sometimes it is a trip to the vet that causes aggression.

Here are some things you can do:

Purchase a black light- scroll down to The Blacklight Shop
Take your blacklight outside about midnight or later, douse all outside lights you can and shine it all around the outside of your home. Pay special attention to doors and windows (typical target spots). Look high and low- cat urine travels.

Do the same thing inside your home and if you see glowing green spots this is old urine stains. They need to be removed with an cleaner that knocks out the enzymes www.zero-odor.com or www.anti-ickypoo.com has products to help.

Aggression is a way a cat communicates. You just have to figure out what he is saying. Is he scared of the other cat, did the other cat pound the salt out of him, and now he just is on edge and wants his space? Or is he perhaps ill, or is his feline friend ill and the scent changing, thus turning a friend into an alien in the home?

How is their space in the house? Do they share everything? Litter pan- water bowl, food dish, toys, you? Make levels where they can get off the floor and not feel so vulnerable. Cat ramps www.katwallks.com cat condos www.felinefurniture.com window perches, clear off shelves so they can get up high and just away from each other.

Don't allow them to share anything, not toys, food bowls, water bowls anything. Especially litter pans- they need to know they have ample space and scent invades space for cats.

Invest in several Comfort Zone Room Diffusers by Farnum Pet. Start burning them in the main rooms they are in.

Never physically threaten or harm your cats (I am NOT saying you are) but physical acts, be it tapping them on the butt, or tapping them on the nose will eventually lead to an aggressive cat.

Don't reinforce their behavior. Most of us when our cats fight- it is a common response to hurry in and break them up, then scoop one up and cuddle and hold it (never recommended by the way) It can get you bit and scratched, and it can cause more animosity with the cat who started the battle in the first place. Separate them (if they are locked in battle, take a wooden kitchen chair and gently place it between their locked bodies, it will startle them apart. The using a dark blanket or large dark-colored towel herd one cat into another room, and shut the door. Leave both cats completely alone (unless one is injured) for at least 3-4 hours afterward.

Good luck