Are you sure the poisoned them? What would drive me nuts is why they would do it in the first place. Did your dogs bark all day and all night? There really is no excuse for what they did, I'm just curious.
As to your question, if this ever happens again, leave the dead dog/baby goats out in the pen for 12-24 hours. It sounds gross, but their mother/pen mates will go over and check them out, then leave and come back, and in 12-24 hours they will figure out their friend/kids are gone, and their mourning will be almost over. In your case, I'm guessing you removed the dead dogs, and the goats are just calling and calling for the dogs to come back. It may take a couple of weeks before everything settles down at your place. Sorry for your loss.