support dogs for asd and aspergers?

Hi everyone, we are a animal loving family, and during our search for a new dog to join us we have worries of which type of dog to get. We are pretty settled on a labrador as these are the dogs used as sipport dogs but, can you train sipport dogs yourself? Has anyone done this? The demand for support dogs is very high and recieving a support dog is difficult. Any chat on this wpould be great.