Canine Copulation

Question
I own 2 Italian Greyhounds, male and female. I found both "tied" the other day. The bitch doesn't show any signs of being in heat. They've been bred before. Is it common that canines copulate when bitches aren't in heat?  

Answer
A female will only stand to be bred when she is in heat.  Heat can be silent in some dogs.  The male is either shooting blanks or she is unable to get pregnant.  If you are trying to breed them, I would suggest a trip to the vet to check a semen sample first.  If he is normal, then you should have her spayed.