Estrus and mating of dogs

The estrus and breeding of bitches is an important part of breeding. Only when we correctly grasp the sexual periodic changes and ovulation period of bitches, can we achieve timely breeding and improve the pregnancy rate and fecundity.

I. the sexual cycle of the bitch

In terms of reproduction, according to the different sexual physiological changes of dogs, the dog sexual cycle is divided into four stages: proestrus, estrus, metestrus and anestrus.

1. Proestrus: from the dripping of mucus with blood from the vulva to the crawling of male dogs, about 8 days (8.2 ±2.5 days). During this period, the corpus luteum produced in the last estrous cycle of the ovary gradually atrophied and new eggs began to grow; the uterine glands grew slightly, the reproductive tract was slightly congested and swollen, and the glands gradually increased. Its external performance is that the vulva is gradually congested and swollen, the frequency of urination increases but the amount is small, and the urine attracts the male dog to smell. The bitch is excited and restless, likes to approach the male dog and play with it, but has no sexual desire (does not accept male dog climbing). When vaginal smears were examined, there were mainly nuclear epithelial cells, a large number of red blood cells and a small amount of neutrophils.

2. Estrus: from the beginning of accepting the male dog to the end of not accepting the climb, that is, the 8th-18th day of dripping blood from the vulva. The female vulva showed a state of congestion and swelling, and the degree of congestion and swelling gradually increased with time, reaching the peak at the peak of estrus; the uterine horn and uterine body were congested, the contraction of the myometrium was strengthened, and the secretory activity of the glands increased; the cervical ducts were relaxed; the follicles of the ovaries developed rapidly and most ovulated in the middle of estrus. From the external performance, the early swelling of the vulva was somewhat subsided, the bleeding mucus decreased, and the color changed from bright red to light red. The smell emitted by the female dog significantly seduced the male dog to chase and climb across. When the male dog licked its vulva or climbed across, its limbs stood motionless, the tail tilted and tilted to one side, the vulva was repeatedly raised, sexual desire appeared, and mating was easy to attack. Vaginal smear examination, mainly keratinized epithelial cells, lack of neutrophils, more red blood cells in the early stage, decreased in the end.

3. Late estrus: after estrus, that is, into the late estrus, lasting about 10 days, the female dog gradually changed from the excited state of sexual desire in estrus to a quiet state; the cervical duct contracted gradually, the secretion of glands decreased gradually, and the amount of mucus secretion was less and sticky; the endometrium gradually thickened, the superficial epithelium was higher, the uterine glands gradually developed, follicles ruptured, and corpus luteum began to form after ovulation. Its external performance is that the bleeding mucus from the vulva is further reduced, the color changes from light red to dark red or colorless, the swelling fades, and most dogs do not accept climbing. During vaginal smear examination, nucleated epithelial cells and neutrophils reappeared, and lack of red blood cells and keratinized cells.

4. Anestrus: it refers to about 6 months (7.0 ±1.5 months) from the late estrus to the next proestrus. At this time, the libido of the bitch has completely stopped and her mental state has completely returned to normal. In the early stage, the endometrium thickens, the surface epithelium is high columnar, the uterine gland is highly developed, enlarged and curved, and the glandular secretory activity is exuberant; in the later stage, the thickened endometrium retracts, showing a low column, the gland becomes smaller, and the secretory activity stops; the corpus luteum of the ovary has been fully developed, so this period is the luteal activity period. Its external performance is vaginal dryness, no blood mucus dripping, do not want to approach the male dog, do not allow the male dog to climb across, the male dog is not interested in its urine and body odor. Vaginal smear examination, mainly nuclear epithelial cells and a small number of neutrophils, lack of red blood cells.

2. Factors affecting the sexual cycle of female dogs.

1. Season: dogs have the characteristics of seasonal breeding. In general, bitches are in estrus twice a year, with an interval of about 6 months. Most monogamous dogs are in estrus in spring and autumn (March-May, September-November); group dogs (such as Beagles) have estrus at all stages of the four seasons, and the seasonality is not obvious. In addition, according to Marshall (1906) and heape (1900), wild dogs in South America and dogs raised in the Arctic Circle also have estrus once a year, and the seasonality is not obvious.

2. Age: due to the increase of age, the metabolic function of the aged dog decreased, and the estrous cycle was disordered, which often prolonged the anestrus and shortened the proestrus and estrus.

3. Proestrus: in general, the proestrus of small dogs comes earlier (for example, Beagle dogs are 6-7 months old), and that of large dogs is later (for example, German shepherds are 8-10 months old). Dogs with proestrus and estrus have longer proestrus and estrus. In addition, nutrition and ambient temperature also affect the first love, those with high nutrition levels are earlier than those with low nutrition levels, and those in the tropics are earlier than those in cold or temperate zones.

4. Nutrition: due to lack of nutrition or excess (obesity), it can also prolong the period of anestrus or lead to abnormal estrus.

5, disease: due to ovarian cysts, uterine pus and other reproductive organ diseases often lead to anestrus for a long time, or non-estrus. In addition, the last litter gave birth to too many babies, several litters in succession, and so on, the bitch body failed to be well adjusted and recovered, which will also lead to long anestrus.

6. Abnormal estrus: (1) quiet estrus. The female dog lacks estrus, but the follicles of her ovaries are still mature and ovulate. In general, when the interval between two consecutive estrus is equal to 2 or 3 times the normal interval, it can be suspected that there is quiet estrus in the middle. The cause of quiet estrus may be due to the imbalance of reproductive hormones. For example, when the secretion of estrogen is insufficient, the performance of estrus is not obvious. Insufficient or lack of prolactin secretion causes early luteal atrophy, so insufficient progesterone secretion will also cause quiet estrus, because insufficient progesterone secretion will reduce the sensitivity of the hypothalamic center to estrogen. (2) short estrus. The oestrus of the bitch is very short, and if you don't pay attention to observation, it is easy to miss the opportunity to mate. The reason may be due to the rapid maturation and rupture of the developing follicles and ovulation, thus shortening the period of estrus, but it may also be caused by the cessation of follicular development. (3) intermittent estrus. The female dog is in estrus for a short time, and the estrus lasts for a long time (some bitches even mate and become pregnant on the 30th day of estrus). This is because the follicles developed alternately, the first developed follicles degenerated midway, and another new follicle developed again, resulting in intermittent estrus. (4) estrus after pregnancy. The bitch is still in estrus during pregnancy, which is called post-pregnancy estrus or false estrus. The main reason is due to the confusion of hormone function, that is, the insufficient function of progesterone secreted by corpus luteum and the hyperfunction of estrogen secreted by placenta.

III. Ovulation period and ovulation number

1. Ovulation period. During the oestrus of female dogs, that is, from the beginning of mating by male dogs, unovulated dogs still account for most of the 48 hours. 90 hours later, the number of unovulated dogs is in the minority, and the ovulation process lasts until 96 hours before all ends. There was no time difference between the left and right ovaries during ovulation. In short, the ovulation period of a female dog begins at the early stage of estrus, and it is generally judged by the following two points: ① estrus dripping blood from the 8th to 14th day (11.2 ±3.0d), and ② ovulation from the 2nd or 3rd day after the female accepted the male dog's climb.

2. Number of ovulations. Dogs are prolific animals, and the left and right ovaries can ovulate several to more than a dozen eggs (6.0 ±1.7) in a single estrus. Small dogs ovulate less, large dogs ovulate more, old dogs and overweight dogs ovulate less, young and middle-aged dogs ovulate more. The number of ovulation in dogs can be inferred according to the number of fetuses born, and the corpus luteum site of the ovary can be examined by autopsy to make an accurate judgment. In general, about 89% of ovulations are conceived or pregnant, and embryos rarely die or melt after conception.

IV. Timely breeding

After the bitch is in estrus, if she wants to mate at the right time, she must master the best time for ovulation and conception. It is reported that the conception rate of eggs is 79% when mating at 54% 41 hours before ovulation, and 83% between the beginning of ovulation and 120 hours, which is the best time for egg fertilization. Therefore, the timing of mating should not be too late or too early. The egg loses its ability to fertilize too late, and the sperm loses motility or dies prematurely. The pregnancy rate and litter rate were the highest when the female was mating 2-4 days after mating (that is, 60ml 108 hours after mating).

Matters needing attention when bitches are in estrus

1. Strengthen feeding and management, do not scatter at will, and strictly prevent mismatch, resulting in mixed varieties.

2. Strengthen the work of hygiene and disinfection, ensure the hygiene of the surrounding environment and vulva, and prevent reproductive tract infection.

3. If the bitch in training is in estrus, it is generally not suitable to train again, and the training should be suspended for about half a month. Because the estrus bitch is excited and restless, looking for a male dog, it is easy to produce external inhibition and the obedience also decreases.

4. Every day, we should carefully observe and record the symptoms of estrus and accurately position the stage of estrus, so as to achieve timely mating.

VI. matters needing attention when mating

1. Puppy bitches are generally not suitable for breeding, so they are only sexually mature and their bodies are not fully mature, otherwise they will hinder their own growth and development and reduce their fecundity.

2. The age of first match. The average age of female dogs is 1.5 years old (it is suitable for mating in the second estrus) and 2.0 years old for male dogs.

3. The number of mating. In one estrus, the bitches should be matched with Lmuri twice with an interval of 48 hours. Male dogs should be bred 40 times a year, not more than 2 times a week.

4. Time and place of mating. Summer in the south is carried out in the morning and evening, and winter in the north should be carried out in the morning or afternoon. The location should choose a quiet environment, preferably in a place that both male and female dogs are familiar with, which is especially important for timid bitches to avoid crowd interference with mating.

5. Sexual experience. First-time bitches, due to lack of sexual experience, especially those who have never come into contact with male dogs since childhood, are not allowed to mate even when they are in estrus. At this time, they are only assisted by their owners (grabbing the collar in one hand and holding the lower abdomen in the other). First-time male dogs, due to lack of sexual experience, often panic and hesitate once they come into contact with bitches, or crawl without an erection, or have incomplete sexual behavior, and only after several times can they have normal sexual behavior. For this reason, it should be treated gently, otherwise it is easy to cause sexual inhibition. It is best to mate with a sexually experienced bitch first.

6. Sexual inhibition in male dogs. Lack of nutrition and exercise, lack of sexual experience, male dogs with several bitches, etc., can lead to sexual inhibition in male dogs. In addition, sexual inhibition is usually caused by errors or rough management. Some incorrect operations during semen collection can also cause sexual inhibition. Because sexual inhibition is often caused by fear, pain and interference during mating or semen collection, the result can also become impotence.

7. Prematch sexual stimulation. Shortly before mating, sensory sexual stimulation is good for mating. Male and female dogs should be allowed to play together, chase for a period of time, and properly restrain the sexual behavior of male dogs. Several times of empty climbing will not lead to sexual inhibition. After 5 times and 6 times of empty climbing, the ejaculatory volume and semen concentration of male dogs can be increased, and the sperm motility is also good. Prematch stimulation can not only increase the volume of ejaculation, improve sperm density and motility, but also cause the release of luteinizing hormone, and then increase the concentration of plaster ketone in blood.

8. Three matches, three unmatched and one morning and one night: have the same advantages, among young dogs, the male dog's grade is higher than the female dog's match; three unmatched: those with the same or opposite disadvantages, the old dog's grade is lower than the female dog's; one morning and one night: the old female dog should be matched early (with blood dripping 8-10 days), and the young female dog should be matched late (with blood dripping 12-14 days).