introducing a new rat

Question
I have a rat named Vinny, and he's been alone for a very long time. I work at the pet store where I adopted him from, and because he was sick when he came in to the store, he was quarantined, from probably February on. He ended up with a permanent head tilt because of the nasty ear infection he had. He's seen the vet a few times to verify that he's healthy, and I am thinking about rescuing another rat from our store.
This new rat was given up by his owner to our store. We don't know why this rat was reliquished, but we discovered a tumor under his chin about a month ago. The rat went to the vet to have it removed, and has been given a clean bill of health. He is also very sweet.
Both have been alone for a very long time, and I am worried that they wont adjust well to each other. Vinny the rat I already have is a biter. I have been working very paitenly with him, but I think its only getting worse. I've stopped hand feeding him to see if it makes a difference, but he bites my fingers any time I reach into his cage. I was also thinking that having another rat around might help with this biting, because he'll get to see how much happier it makes me not to have bloody fingers.
I have read about introducing the rats in neutral territory, and using vanilla extract to confuse the scents, but I wanted to get an opinion on my specific situation. I also have a very large cage (about 4 feet long by 2.5 feet wide and about 3 feet tall) that Vinny is currently living in, so I do not think that room would be a problem.

Answer
Lauren,

I would recommend, if you do try to get a cagemate for Vinny, that is is younger, 3 months or so and do a very slow introduction. Also, make sure that the new rat is very social. If Vinny is having trust and biting issues, that is from lack of socialization, but also possible hormone aggression. If it is hormone aggression, he could attack and kill a cage mate, so you do have to be careful of this. The reason you wan to have a very social rat for a cage mate is because rats learn from each other. IF Vinny will accept a cagemate, then you will want one who will be a good influence on him and maybe help him to trust you more.

I am curious to know if Vinny bites outside of the cage. If he doesn't, then you could use a towel to get him out, covering his face to reduce his stress and fear, and work with him outside of the cage only.

Also, peas are a wonderful tool. I tend to refer to them as rat crack because they become addicted to them almost. For 3-4 days, open the cage, but in a small dish of about a teaspoon of thawed frozen peas (do not use canned, too high in sodium) and walk away. DO not talk to him, do not try to interact with him, just open the cage, put in the peas and walk away. Do this 4-5 times a day. After 4 days, when you put the peas in, leave your hand in for a bit, but if he bites you, remove the peas and try again in an hour. You need to get him to associate your scent and your hand with good things. If you get him out during this time, use the towel trick, so he does not associate the peas or anything else you do with coming out. Each time he allows you to put the peas in without biting you is a step forward and a reason to leave the peas in, but if he does bite, even if he does not draw blood, then take the peas out. If, in a week, he is still biting and still drawing blood, I would talk to a vet about getting him fixed before trying to introduce a cage mate. If he can not learn to trust, then it is most likely hormones, not just lack of socialization. Keep in mind, it can take up to 8 weeks for his hormones to completely drop down.

When you do get him a cage mate, go slowly, at Vinny's pace, do cages side by side first, then put the new rat in Vinny's cage and Vinny in the new rat's cage. Then a neutral area, like your bed or the bathtub. I have heard of ppl using vanilla, but I have also heard of ppl having luck with covering both rats in pudding. It may sound strange, but the rats are so busy cleaning themselves and each other off, that they do not realize that there is a stranger in their area until they have cleaned each other off and bonded...over pudding.

Tami
Social Rats Adoption and Rescue - Chicago, IL