Chances of pregnancy

Question
I have a 12 month old lab mix female. She has shown no signs of being in heat, but she got off her lead today and was gone for about an hour. When she returned, it was evident that she had mated with a male - what are the odds that she is pregnant?
It's ironic - she was going to spayed in the next month...

Answer
Hi January - wow, what a great name!  

Most female dogs will not mate if they are not in heat.  The sign/stages of heat are as follows:

Days 1 - 7:  The vaginal area swells noticeably and within a couple of days bleeding begins.  During this stage the female usually will not allow the male to mate with her, and she will actually growl and possible bite him if he tries.

Days 7 - 14:  It is during this stage, the female is in what is called Estrus, and will now allow the male to mate with her.  She will normally stand still and move her tail out of the way.

Days 14 - 21:  If successful mating occurred during days 7 - 14, this is the stage where the embryos are forming.  No external signs are present.

If you have not noticed any of the above signs, then I feel it is safe to assume that she did not successfully  mate, and it is safe to have her spayed next month.  However, if you are not sure, you can have her examined by your vet during the pre-op exam before the spay procedure.

Good luck, and please do not hesitate to contact me if you have additional questions.  I would also like to apologize for the delay in answering your question.  I am having some work done on my home and my internet connection was interrupted.

Sincerely,
Penny DiLoreto
www.puppies-dot-com.com