behavioral changes in my cat

Question
I have had Oliver for a little over a year now, since he was a kitten. I had never had any problems with biting or scratching. He has always been really friendly and pleasant to be around. Im a college student and recently I went home for around a week and had to leave him at my apartment because it was too much money to fly him and I didnt want to scare him. I decided to keep him inside because there is a pesky raccoon thats been coming around and I was worried it would eat all his food. He started off as an indoor cat but now hes become an indoor/outdoor cat. Anyhow, when i got back he still had enough food and water but i knew that he would be upset about being alone and not being able to go outside. He didnt retalitate by peeing or pooping on the carpet or anything and seemed ok at first, but then his behavior started to change. Sometimes he will  be really sweet and affectionate like always. But other times he will continuously try to bite me and meow in an aggressive manner. Ive tried saying ow and no sternly but it seems to make him want to bite me more. Im worried that me leaving him home has done some kind of permanent damage. Im also concerned that the raccoon could have had some kind of disease and infected my cat. I would appreciate advice on what to do when he has these mood swings and what steps if any I can take to get him back to his old self

Answer
Molly,

Any cat who suddenly becomes aggressive should be taken to your regular veterinarian for a complete checkup to rule out a medical issue causing the behavior change. Certain kinds of diseases, illnesses, or being in pain can cause cats to show aggression.

If it is not a medical issue then your cat is trying to tell you something by his behavior. Sometimes cats get overly excited and bite, he may be upset at you for leaving him, or he may now be insecure that you are going to leave him again. He also can be telling you that he is bored and wants attention and wants to play. A kitty laser light is a good interactive toy. Or  you could get him a kitty friend his own age to play kitty games with, cuddle with, and to comfort him and keep him company when you are gone.

When he bites and you are holding him or near him, loudly and firmly say "don't bite!!" and dump him to the floor and ignore him. Wait a few minutes then pick him up and love on him. If he bites again, repeat. Keep doing it until he associates biting with your loud voice, getting dumped, and no affection.

If he is traumatized by you being gone and scared you are going to leave him again, it will take a little while for him to settle back down to his regular self. He will when he sees you are not leaving again. Keep giving him lots of love and attention (but not when he bites!) to reassure him. Give him lots of kitty treat too. Food is a great bribe!  And don't worry, I would doubt seriously that you have caused him any permanent damage.

If the raccoon is not rabid, it is not likely that it will attack your cat unless the cat is being aggressive and acting territorial. Raccoons are nocturnal animals and a sign that a raccoon is rabid is when you see it in the daytime.

Here is a link to a good article about raccoons: (copy and paste, or type the whole link into your address bar)
http://www.projectwildlife.org/living-raccoons.htm

I hope this helped.
Tabbi