can u bring your therapy dog in if he is in a carrying case

Yes

Of course you can. Therapy dogs are allowed EVERYWHERE. Refusing one is a violation of the ADA. You do not have to show papers anywhere. The employees are allowed to ask only two questions: is this a therapy dog and what has the dog been trained to do. You can say as little as to alert me when needed. It is absolutely against the law to ask for papers and/or what your disability is that requires the animal.

Yup

I would call the zoo first and ask if it was ok to bring a therapy dog

Yes you can bring your pet with the proper identification. ..must be leashed

Yes, make sure you have your dog's official vest on him for ease of identification that he is a therapy dog or his papers and must be on a leash. Pets that are not therapy animals are not allowed.