An individual can qualify for a Service Dog Certification if they have any kind of disability which requires a Service Dog for assist. The disability may be physical like blindness, lack of movement, epilepsy, diabetes, etc. or a mental or emotional condition that involves a medical support dog. For a person with a disability, a Service Dog must be explicitly trained to do work or perform tasks. People with mental or emotional disorders can also have an Emotional Support Animal, which does not require special training and has more limited privileges than Service Dogs.
There are federal regulations intended to protect you from being discriminated against and to require you to be accompanied in public by your registered service dog — even if pets are not permitted. You can also live in housing with your licensed service dog or licensed ESA if pets are not allowed.