When is a dog old enough?

[heavyhorse]

Pretty much what WGW said above.  




A lot of male animals will start "acting sexual" at a very early age.  Ram and goat kids will mount and hump while they are still nursing.  Doesn't mean they are actually ready.  Keep in mind in nature a young male won't be allowed by the others in his group to breed; the resident male will "educate" him on appropriate behavior, the females mostly won't "stand" for him even in heat.  




In my experience (working livestock farm and small-time giant breed dog breeder) they aren't physically mature until 18 - 24 months.  




And my gawd make sure he's gotten his puppy shots....