An ESA dog is a dog that provides emotional support and comfort to individuals with mental or emotional conditions, such as anxiety, depression, and certain phobias. It is not considered a service dog, and ESA users do not receive the same rights as service dog users. To legally have an ESA dog, the owner must be considered to have a qualifying mental health or psychiatric disability by a licensed mental health professional, such as a therapist, psychologist, or psychiatrist, and have a properly formatted prescription letter. ESA dogs can be of any age and any breed, and there are no restrictions on their species, breed, size, or weight. However, some ESA-friendly airlines may have certain restrictions in place when it comes to a dog’s breed, and other airlines may not allow certain species, such as exotic animals, onboard flights.