I'm not sure if garlic has much effect on fleas but it is supposed to be a good antioxidant, a bit sure can't hurt I wouldn't think. I have never heard anything about turkey skin before, in fact when my RB Willie had stomach problems when he was elderly, a turkey and barley formula dog food was one of the only foods he seemed able to tolerate.

I have read chocolate and onions in large amounts can be very harmful.