If you ask domestic vets locally, they can refer you to one. You should definitely use a vet that has experience with exotics. I have known cats that died because of inexperienced vets. They require unique vaccination programs, anesthesia, etc. You will need to locate a vet first , because U.S.D.A. will need information on them before they license you.
Cougars are a popular breed in the pet trade and completely over-represented.
If you are considering not spaying your female cougar, you must listen to this recording of a female in estrus. Training and Safety. The most important information you will need is on handling and training. This comes from experience . No matter how tame your cat, he can kill you if you do the wrong thing.