I was talking to a vet just yesterday and somehow got on the topic of weightlifting / nutrition. He is a fairly big guy, I think he tips the scale at 225 and very lean (at 6'3"). He is a Vet and he mentioned to me that numerous times he has had people come in wanting to get their dog on a cycle of winny. He says mostly pitbull people who just want their dog to bulk up.
I couldn't believe I was hearing this so of course I continued to prod. Apparently, it is a very strict procedure to use winny on animals, he equated it to the same "tight collar" that you would see from a physician prescribing HRT. They need specific blood work done every 3-6 months depending on the age of the dog, and they need to have cited reasons for its use. As you would guess, the shot needs to be given in the facility.