could my chihuahua have become pregnant

Question
Before any bleeding I could tell that my chihuahua was going into heat so I took her to visit a friend's male to breed her. He chased her for hours and we all tried to keep a close watch. After a while they both came out from behind the couch and lay down next to each other calmly. The male did not persue her any more after that. Can I assume that they did what was necessary?

Answer
Hi Susan

The most common reason for a breeding to be missed is timing.

A heat cycle last 21 days but the ONSET of a heat cycle last 6 - 9 days, you can tell this by the bloody discharge and the swelling of the vulva.  And it's during this time that the female attracts the male through the pheromones she discharges.
If a male tries to mate with her she will not accept him, either by running away, sitting down, or snapping at him.

Standing heat is when she's receptive.  It usually occurs a day or two before she ovulates.  She raises her tail, flags it to the side and presents herself.  You will also notice that her vulva has softened and the discharge is a light pink color.

Once your female is ready and they have had a tie and are locked together, sometimes 15 - 60 minutes.  

If you leave a male and female together too long before a female is ready, they can both become frustrated and tired out.

So unless she was in standing heat, I would have to say no.