How do you know the dogs have mated?

You can't really tell until a while after they have mated. After a while the female dog becomes rounder and crankier and the male may run out on roads looking for the female dog. If you haven't noticed anything you'd probably notice when the dog has the pups.

IF YOU THINK YOUR DOG IS PREGNANT YOU MUST CONSULT A VET!

anon

Unless you actually see the dogs "tie" you probably won't know until she shows signs of pregnancy which can be a week before whelping. Typically when trying to breed you would have the two dogs in a controlled setting where you can keep an eye on them. If they truly mate they will be tied or stuck together for a period of time. If you did not observe the tie and really want to know; it is possible to have a ultra sound done on the dog to see if she is carrying puppies.