There are many supplements offered to help prevent your dogs urine from staining the grass. It seems that some work for some dogs, some for others and some for nobody. Only way to tell is to try them, start with the Nuturvet or Vetriscience products. There are also products to pretreat your yard with to help break down some of the compounds in urine that lead to staining. Again, the only way to see is give it a try in your yard.
The above products do not represent a danger to your dog if used properly.