We thought it would be a good idea to worm our female adult doberman while she is nursing. On the box it says that it is safe for nursing dogs, but once again Hartz is lying. The puppies are three weeks old and are growing rapidly, healthy, and adorable. After worming the female two days ago, three of six puppies have been poisoned by Hartz wormer and killed. As you know, dogs are worth hundreds of dollars, but more than that they are precious puppies that have been murdered by Hartz. We are praying that the other three puppies will survive the night, and also the female dog. DO NOT BUY HARTZ.