Answer:
The gestation period is the time between conception and birth. For a dog it lasts approximately 58-63 days. However puppies may be delivered between 58 and 65 days.
Female dogs, or bitches, will mate only when in heat, or estrus, which occurs about every six months and lasts from 18 to 22 days. Whelping (giving birth) occurs after a gestation period of about nine weeks. The size of the litter varies to some extent with the size of the dog: toy dogs rarely bear more than 2 puppies, while the largest breeds average closer to 10.