We used to have a chinchilla before I developed an allergy to his hay. We had him in a cage at home from day one, where he could interact with our cats through a mesh screen. Both of our cats are pretty low on the prey-drive, but we still made sure to watch the chin, not just for when the cats were around, but any time he was out and about in the house. Chins are very destructive and love to chew on things, which was more of a concern for us than the potential for our cats to chase.
Because cats naturally prey on chinchillas, it's most likely going to cause the chin more frustration than it is your cats when chin comes home. Here is what we did, and what I recommend:
- Bring Chin home and keep in a cage where he can veg for at least a week. They are very sensitive to fear and can have a heart attack if they get scared. New environments, new noises, new people - all of that is stressful to them.
- Leave him be for a few days. The cats will smell him, and will acclimatise to his presence quickly. After a few days of being left alone, bring him out for short periods and let him explore. Try to do this with your cats nearby and keep a close eye on everybody. Let your cat see you playing with chin so they associate him with something that is yours and something you like. You can give your cats treats during this play time too. Not necessary but it can get some positive associations for having chin around.
- Gradually lengthen the time he is out and playing - but if he gets too nervous, starts barking or chatting his teeth, put him away to let him calm down.
- As he is more comfortable, let the cats 'meet' him. Hold onto him and let the cat smell him. We let our cats smell ours face-to-face, and everyone was quite pleasant.
Remember that a chinchilla is prey to a cat and even if they are buds sometimes the predator instinct kicks in and a cat might chase the chin. We ALWAYS were in the room when all the pets were out, just to make sure nothing happened. As I said before, we were always more worried about the chin chewing a power cord or finding a new hiding spot than we were with our cats' behavior.