In the US the ADA, FHA and other legistration consider Service Animals (SD), Emotional Support Animals (ESA) and Therapy Animals (TA) for different purposes. However, the common denominator is all are dogs with one exception for Service Animals. Service Animals now includes miniature horses as well.

A Therapy Animal is a dog that has gone through a streneous obedience training and test. They usually do not perform any specific task for clients. However they may be trained to perform behaviors for entertainment.

Emotional Support Animals are dogs that have been prescribed by a medical or psychiatric professional to help the handler cope with strong and difficult emotions. They usually are not trained for specific tasks for the handler. The also DO NOT have special permissions outside of the home. However prescribed ESA's are covered by the FHA.

Service Animal is a dog or miniture horse that has been trained one or more specific tasks to help accommodate the handlers disability. A medical or psychiatric professional must have diagnosed the handler with a disability. And as stated before the animal must be trained to assist the handler with their disability. Also, one cannot claim the natural calming effect as a specific task. It must be a trained one. Psychiatric Service Dogs are usually trained 2 or more specific tasks to ensure that their animal is covered by the ADA laws. Service animals are the only animals that have special permissions and exceptions regarding entrance into different facilities including restaurants, shops and hospitals.

You will need to have your medical or psychiatric professional know you would like an ESA or a SD. (Depending if you have a disability or not.).

It is sad to hear about your roommate but ESA''s and Service Dogs are assigned for use by the owner/handler.

I don't know how helpful all of this is but hopefully it will help you in making your decision.

Good Luck!