Dogs may still get injured so be prepared. Most hunts are held on non-fenced fields but don't take a chance. Some people only course in fields they have personally checked to be fence free. Most of the time Borzoi will return at the end of the hunt. Of course there is that exception.
Some people recommend using a whistle or game caller such as a crow call or predator call.
Again, practice at home with treats for reward. If all this fails, try to think as your dog might think as your walk, call and look. While precautions are taken, injuries still occur. The risks are real. The coursing of live game is a blood sport and if you are someone who is indisposed towards this, you will not like this form of coursing.