If the dog was not diseased, and had his shots, then what he did was perfectly safe except for the possible damage that could have been caused by the actual action. Disease wise hes safe. I dog keeps his penis cleaner than the average man does. And a dog with all his shots carries 0 human transmitable diseases. However the dogs penis may need cared for as there are plenty of dog transmitable diseases possible and the thought that a ripped knot, broken ozbone, or breaking of the skin could have occured.