Normally I would just direct you to the search feature, but when it regards pets, I usually have a few bookmarked.
This is a good thread:
topic2312.html?hilit=petsThe process for bringing cats should be no different from bringing dogs. We came from Canada, and while I have seen my neighbors to the South have a few more problems bringing their pets in at times, the issue seems to be not with importing them so much as inconsistency as to what is needed or required according to the information available in the States. FWIW, I checked the Chilean Aduana page and cross referenced it with what the consulates listed. I say consulates, because I spoke with the one in Toronto, the one in Vancouver and the Chilean Embassy for good measure. A couple phone calls and 20 minutes of surfing are easy enough and saved me alot of head ache. There is a form that the Canadian Food Inspection Agency provides for Pet Export and it was referenced by the Embassy and only one of the Consulates. Basically, you take your pet to the vet, get their international health certificate and they fill out this form and sign it. Then you take it to CFA and it gets stamped by an official government vet. Costs about $25 or so (on top of whatever the vet charges) and it's all official. When I asked the consulate in Toronto whether I needed it, they said they never bothered, and they didn't have any problems. Being that I am OCD, I ignored them and went to CFA to get this form stamped. When we got to Chile, the ONLY thing the customs vet asked for was the form the Chilean Consulate said we did not need. Hooray for OCD.
Interestingly enough, the Chilean Customs guy couldn't read the Canadian Goverment doc, he just kind of knew what to look for. It was training day the day I arrived and I got to watch him explain to the newbie what to look for. They verified the vaccines (rabies mostly) and that the animal had had a recent parasitic treatment (regardless of whether or not they had any problems, you'll still have to do it) and then the number one thing he told the newbie to look for was the Canadian Government Vet stamp. So the point is, chances are you will speak to a Consulate who will tell you you don't need something. Consulate is, by and large, government speak for Incompetent. Play the paranoid card and just insist on getting it for your own sake. Better more paperwork than not enough.
BTW, don't plan on bringing their food or meds with you. They will be confiscated at the airport. If you don't declare them and they find them, it's a hefty fine. I managed to sneak stuff in mostly because I was lucky and quite frankly I forgot what I packed and where. So I handed over the treats in my carry on when they asked if I need to declare anything, but the food and meds shoved in a couple boots in my checked luggage went through fine. I know of one person that was fined $200+. Go figure.
Oh and be prepared to watch your poor cats come out on the luggage carousel with the rest of the luggage. My Voodoo was not impressed. I got the cold shoulder after he spent a half hour peeing lol. Good luck!