Here's a little something, not sure if you watched the dogs get it on or not so I pasted both parts of the question.
Question:
How do you know if your dog is pregnant?
Answer:
If you witnessed the mating chances are your dog is pregnant. You can calculate 62-63 days gestation period from the mating date.
If you did not witness the mating than evidence of pregnancy will only be evident several weeks into the gestation (between week 6-8).
At this time an X-ray taken at your veterinarian will confirm fetuses.
Signs late in the gestation period
The female's mammary glands will have started to swell up with milk..
Behavioral changes such as turning in circles in search of a nest, anxiousness, decreased appetite, and a characteristic decrease in body temperature to 100 degrees Fahrenheit 24 hours before giving birth. (Normal body temperature 100.5-102.5F).