Dog gestation time is an average of 63 days. Dogs can carry puppies between 58 and 68 days. Dogs have a heat cycle that lasts 18 to 21 days. During this time they go through 4 stages with the heat cycle. These four stages are proestrus, estrus, diestrus, and anestrus.
Stage two which is Estrus is the stage in which the female dog can get pregnant and will permit breeding with a male. Being familiar with a dog’s cycle can be very helpful in determining just when it gets pregnant and how long it will until the dog goes into labor according to this.