Answer
Dorothy:
If you are asking about male dogs, yes it is normal for them to have nipples.
The best way of explaining this is.When puppies are formed in the females(mother dogs) womb, it is too soon to establish the sex of the puppies. Consequently both male and female puppies are born with nipples.
All human males also have nipples. Perhaps there are no males in your family. However if you use a swimming pool, you will see that all of the men and boys have nipples.
Stephen:
All mammals, of both sexes have nipples.
Ziggy:
Yes no worries it is normal
All mammals have nipples, otherwise they won't be able to feed their young
