There are many factors that cause infertility in breeding dogs. The first is congenital factors: 1. Malformation of reproductive organs. Female dogs lack vulva and vagina, vaginal atresia or overdevelopment of urethral valves. Animal B-ultrasound examination found that the uterus was underdeveloped, lacked uterine horns or lacked cervix, etc. 2. Hermaphroditism. Female dogs have bisexual reproductive organs, with a longer perineum, narrow vulva, and a developed clitoris similar to the glans. When animal B-ultrasound examination of internal reproductive organs, it can be found that there are both ovaries and testicles, and some have only testicles but no ovaries. 3. Childish disease. After the female dog reaches sexual maturity, animal B-ultrasound examination shows that the reproductive organs are still underdeveloped or have no reproductive capacity. When Animal B-ultrasound examination of reproductive organs, it can be found that the labia and cervix are underdeveloped, the vagina is short and narrow, and the uterus and ovaries are very small. In such cases, timely treatment can be carried out.

Management factors: 1. Unreasonable feeding, exercise, rest, sanitary conditions, breeding plans and other management measures have a certain impact on dog reproduction, and animal B-ultrasound examination is required frequently. 2. Environmental impact. When the breeding environment suddenly changes, the bitch cannot adapt to the stimulation of adverse stress factors in the local external environment, which can also cause infertility in the bitch. It is necessary to conduct animal B-ultrasound examination in time after mating. 3. Temperature influence. High temperature can interfere with the hormone secretion of the bitch, indirectly affect the ovarian function, increase the abnormal estrus and anestrus rate of the bitch, cause the dog's sexual function to decline, and hinder reproduction. High temperature can increase the adrenocorticotropic hormone in the blood of male dogs, thereby inhibiting the production of steroids in the testicles, causing the male dog's mating desire to decrease.