This is Zoey. Zoey is a Service Dog. She is being trained in a classroom here. What is the difference, you may be asking yourself, between Service Dogs, a Therapy Dog, or a Emotional Support Animal?
A Service Dog is a dog who has a specific job that it is trained to do to help it's person. They are allowed everywhere their owner goes because at any given time they may need to be present to do their job. They must "do" something, whether it be licking their owner, jumping on them, or it could be as small as preventing a child from running away. Some guide their owner acting as their eyes, or their ears. A service dog's job is much more than what then their task is. They have to be well behaved, they have to pay close attention to their owner's body chemistry and body language. They are very brave when they don't want to be, they must put their person ahead of themselves at all times. However, they are dogs, they are not perfect. Sometimes diabetic service dogs will alert to other people that are not their owners, they may jump on them, or lick them. This attention may be unwanted, or simply being a dog they may act as a dog. Service dogs love people, most of the time they are breeds who love children. Other people and children can thus become a big distraction to them doing their job.
A Service dog can be any breed of dog, even one you are not used to seeing as a service dog. They can be large Great Danes, Pit Bulls, or even small dogs such as a Papillon. They do not need to be certified, or have come from a specific school. They do not need a vest, but when they wear one it makes it much easier to tell that they are working. Please do not judge a Service Dog by what you think one should look like. The larger dogs such as a Mastiff or a Dane a lot of times are used for those who have balance issues or muscular problems that they need help with. They could also be used for those who get lost. Others may be seizure or diabetic alert dogs. Those can be any dog, they could have been a pet and started alerting on their own, or they may be specially trained dogs who were bought for this specific reason. Either way they are service dogs, real service dogs.
Therapy dogs are again any breed of dog (or animal for that matter). They are specifically trained to be well behaved and give love and support to those who need it. Normally this is done at a hospital, school, or nursing home. They are certified and trained, most of the time their training is done through a program such as Pet Partners.
This was my dog Pippin about 10 years ago. He was a certified Therapy dog. He was wonderful with people and knew who needed him. I could not bring him into stores with me, I also had to certify him, get him an official badge, and follow specific protocol.
I know people who have horses, chickens, ferrets, rabbits, or even cats who go to hospitals and nursing homes to give therapy to people.
An Emotional Support Animal is, in general, a person's pet who was acquired for a person who has anxiety or other emotional problems. They do perform a kind of service, they don't however fall under the service dog umbrella, unfortunately. They are not required to be trained other than to be a well behaved dog. The exception to this rule would be a PTSD dogs.
Every state has their own quips and qualms and differences in the little things, such as in Oregon Service dogs in training are allowed the same rights and privileges as a fully trained one. That makes training them much easier. However not all states have that in law. So it's your responsibility to check and learn for yourself what the laws in your states are.
A few things as far as the public's responsibility goes with these dogs. If someone tells you that their dog is one of the above listed, understand that you may need to change your behavior. You may need to refrain from petting the dog, move around the dog (give them space), or refrain from judging. You are not allowed to ask what issues the person has, only what specific jobs the dog is to do. Seeing a service dog working out and about does not mean that they stop being dogs. It does mean that the person who is attached to the other end of the leash might need a bit of space, and or understanding. Someone who has a service dog has a need of it to help them with their living of their life, just as a person who has a wheelchair. Follow the rule of "If you wouldn't say it or do it to someone in a wheelchair, don't say or do it to someone with a Service Dog."
Remember, their needs are just as valid.
Please let's be compassionate to one another.