Among the many reasons for non-pregnancy, the inability to determine the ovulation time and the most suitable breeding time of female dogs may be an important cause. The author analyzes the methods to determine the ovulation time of female dogs from the aspects of investigating reproductive history, clinical examination, laboratory examination, laparoscope observation of uterine and ovarian changes, and strives to find the method to determine the most suitable breeding time for reference.
I. Investigation of reproductive history mainly includes age, health status, epidemic prevention system, feeding management, previous estrus time and cycle, pregnancy and parturition, number of puppies, weaning time and number of weaned puppies, family reproductive capacity, whether contraceptives or pregnancy interruption drugs are used, etc.
II. Clinical Examination
(I) Vulva examination. In the early stage of estrus, the vulva is edematous and enlarged, and bloody secretions flow out. The vulva and tail hair are wet and sticky. In the estrus stage, the edema is obvious, and the tail swings to one side and the hindquarters rise when touching the vulva and vulva. In the later stage of estrus, the edema subsides. After 1-2 weeks of the end of estrus, the vulva is small, wrinkled, and has good tension.
(II) Vaginal secretions examination. Vaginal and uterine secretions flow out during estrus, childbirth, a certain stage after childbirth, and under certain pathological conditions. In the early stage of estrus, the secretions are bloody, and the color of the secretions gradually changes to yellow or straw yellow. There is little or no discharge of secretions in the late estrus and anestrus.
(III) Vaginal examination. After cleaning the vulva, use a speculum and cooperate with an appropriate light source to observe the mucosa and secretions and feel the tension of the vagina. In the early stage of estrus, the edema is obvious, the mucosal surface is smooth, and the speculum is easy to insert. In the later stage of this period, there is resistance, the mucosa is rose red, edematous, wrinkled, and a large amount of blood-stained secretions can be seen. The cervix is slightly open. In the estrus stage, there is resistance when inserting the speculum, the mucosa is thickened, pale, and wrinkled. Since the changes of vulva, vagina and secretions are secondary to the changes of hormone levels in the body, it is not accurate enough to estimate the ovulation time, and it needs to rely on experience. When this method is used to determine the breeding time, it should be bred twice at an interval of 48 hours.
(I) Cytological examination. The changes of vaginal epithelial cells are closely related to the changes of estrogen level. Sampling should be carried out at an interval of 24 hours, combined with other clinical examination and reproductive history investigation. The dog is fixed on the desktop, the vagina is kept horizontal, the vulva is separated with two fingers, and the sample is collected with isotonic saline soaked cotton ball and fine tube. When collecting samples with cotton balls, insert them into the vagina, rotate them and take them out. When collecting samples with fine tubes, insert them into the cervix, withdraw them slightly, squeeze out a few drops of isotonic saline, then suck them into the fine tubes and take them out.
Place the collected samples on a slide, smear them with another slide, fix them, stain them, and then examine them with an ordinary microscope. For unstained ones, a phase contrast microscope can be used. In the early stage of estrus, the epithelial cells have nuclei. A large number of basal-like cells and intermediate cells appear in the early stage, as well as white blood cells and red blood cells. In the later stage, the number of basal-like cells, small and medium-sized cells, red and white blood cells decreases, and eosinophilic epidermal cells appear. At the beginning of estrus, a large number of eosinophilic and basophilic epidermal cells and some large intermediate cells appear, as well as a few acellular cells and red blood cells. In the later stage of this period, mainly eosinophilic epidermal cells, acellular cells, cell debris, white blood cells and nucleated epithelial cells reappear.
In the late estrus, epidermal cells still exist, and basal-like cells and intermediate cells increase. In the first 10 days of this period, the number of white blood cells increases, then decreases, and disappears after 20 days. Foam cells and late estrus cells appear in large numbers. In the anestrus stage, a small number of basal-like cells, intermediate cells and white blood cells can be seen, and sometimes foam cells can be seen. It should be noted that vaginal cytological examination cannot determine the occurrence of LH peak and ovulation.
