In the proestrus period of a Labrador, eggs fill the entire ovary, and bloody fluid will flow out of the vagina. When the ovaries are examined with veterinary B-ultrasound, many follicles can be found. The female dog's genital vulva will become twice the normal size. It lasts for 4-15 days, usually about 12 days.

Since the transition period from proestrus to estrus is difficult to detect, it can be judged by observing the size of the follicles with veterinary B-ultrasound. The female dog's vulva remains swollen, and the secretions in the inner vagina carry less blood until the secretions are completely cleared and enter the estrus period with mucus. If the secretions of the Labrador are yellow, don't be nervous. If the secretions are too much and last for more than two weeks, you should pay attention. Male dogs are attracted to female dogs, and female dogs will also let male dogs approach them and mate with them. Before mating, it is best to use veterinary B-ultrasound to observe the volume of their follicles.

Prenatal preparation: Before the mother dog gives birth, it is mainly necessary to prepare a place suitable for giving birth. The breeder can use a dog bed for the dog and the puppies to live. The dog should be kept quiet during the birth, because some mother dogs do not like people to disturb their puppies. When the mother dog has just given birth to the puppies, the mood will be bad. The breeder should be patient. If the mother dog often leaves the puppies, it should be led back to the dog bed to let it get used to accompanying the puppies in the dog bed, and the technician should use veterinary B-ultrasound to observe the fetal heartbeat of the mother dog.

The general gestation period of Labrador dogs is 60-63 days. The breeder can make a final check before the dog gives birth. The fetal condition can be observed by veterinary B-ultrasound. The mother dog will be unwilling to eat within 24 hours before giving birth. The breeder can prepare some clean water for it. The body temperature of the mother dog will drop from 38.5℃ to 37℃ when it is about to give birth. This is normal. Don't worry. Using veterinary B-ultrasound to observe the number of fetal heartbeats is an important means.