Hi... My question is whether it is possible to overdo vitamins in feeding your dog. I currently feed Natural Balance Fish and Sweet Potato (I have another thread going on alternatives), but I also add Missing Link and a multivitamin/probiotic/digestive enzyme supplement. Anyone think this is overkill??? Is it possibly dangerous or detrimental? My dog came to me with demodectic mange, so I have been mainly concerned with boosting his immune system.