Our personal therapy dogs that we use are Dachshunds and Bullmastiffs. Virtually any breed or mixbreed dog can be used for Therapy, as it comes down to the individual dog and the individual handler. Selecting a dog to do Therapy work really is best when the dog is naturally attracted to strangers in all public situations. When that's not the case, some dogs can have modified training to learn to enjoy it, and others just tolerate it. Coming from someone who does a LOT of volunteer therapy work within the community, I can say without a doubt it's much more enjoyable for both when the dog naturally seeks out human companionship from outside its pack.