I slightly disagree. First of all, there's a difference between a therapy dog and a service dog. What this person is looking for is a service dog, i.e. a dog trained to perform tasks for somebody. Such dogs come from specialized breeders and they use only certain breeds. Labradors are popular service dogs because they have the right size for many tasks like guiding the blind, they have a calm temperament and have been bred to have a "will to please". They were originally working dogs, as the name says, retrievers. They pick up after the shot, and they want their master to be happy with them, which makes them suitable for teaching them to perform tasks. There's other popular breeds as well, and then there's those doodles which are technically mutts. People will sometimes talk about their "pure-bred Golden Doodle", but they are absolutely mixes, their parents belong to different breeds, after all. Some people believe that if you breed labs and goldies with poodles, you end up with a hypoallergenic dog, but this has been debunked. So far, there is no hypoallergenic dog. However, if you want a dog that does not shed, a breed with hair that grows indefinitely instead of falling out might be the answer. Asking for a chocolate-colored one is pure entitlement, even if you were willing to pay for your service dog yourself you cannot always get the color of your choice because it is irrelevant. Unless we're talking merle, the merle factor has been linked to genetic defects.