gestation and delivery in bitches

gestation and delivery in bitches

physiology, pregnancy diagnosis, and treatment of dystocias :
Bitches have different reproductive peculiarities when compared to other species the length of the fertile period, ovulation, maturation and fertilization of the oocytes. High rates of dystocia are observed in this species, especially in some races. This review article aimed to address the aspects related to pregnancy and childbirth of this species, with emphasis on dystocia. they were described physiological events of cleavage and embryonic implantation, hormonal control of pregnancy, as well as ways to calculate its duration. in addition, possible methods of pregnancy diagnosis were discussed, relating their advantages and disadvantages. The aspects of the trigger were also described physiological of childbirth, the main maternal and fetal causes of dystocia, and the examination of the patient in dystocia. All the treatment possibilities for the bitch in dystocia were emphasized and discussed, as well as the main drugs to be used for anesthesia in cesarean sections.

The obstetric care to bitches for pregnancy diagnosis, pregnant women or in dystocia is very important. frequent on the part of the veterinary clinician of pets. This way, it is necessary the knowledge about pregnancy and childbirth in this species. The reproductive cycle of the bitch presents unique aspects when compared to other domestic animals. Some particular aspects include the duration of the sexual receptivity and the fertile period, ovulation of immature oocytes, the long viability of the oocytes and the spermatozoa, and the different rates of embryonic cleavage depending on oocyte maturation in the moment of fertilization. An important characteristic of the bitch's gestation is the maintenance of the concentrations progesterone plasma be exclusive of luteal origin, and be the luteal bodies dependent on the action autotrophic prolactin, especially in the second half of pregnancy. Among the methods for diagnosis during pregnancy, abdominal palpation, radiographic and ultrasound examinations and plasma dosage of relaxes, a new rapid method for diagnosis. Bitches of various breeds can be affected by dystocia, and especially those of the brachycephalic races. The adequate examination of the bitch in dystocia is fundamental for the decision as to which treatment is to be employed. The choice of the correct anesthetics for the performance of the cesarean section is essential so that you have little or no fetal depression.

Physiological aspects of pregnancy In order for pregnancy to occur, it is necessary to have copulation or artificial insemination (AI), fertilization of the oocytes, implantation and embryonic development.


The fertile period of the dog extends from the end of the proestrus to the middle of the estrus. Each one of these two phases of the dog's estral cycle can last from three days to three weeks, with an average duration of seven to ten days. Canine sperm may remain stored in glands uterine during estrous and the proximity of the sperm to the columnar epithelium not only helps to maintain its viability but can also promote or modulate sperm capacity building and changes in motility. During the follicular phase of the cycle (proestrus and estrus), monovular follicles (with only an egg cell) or polyovular (containing on average two to four egg cells) develop in the ovaries.

Ovulations occur on average 48 hours after the pre-ovulatory peak of luteinizing hormone (LH), although in this period the oocytes are not yet fertilizable, because they are ovulated as primary oocytes, in the germination stage, and a period of two to three days is necessary for maturation to occur in the oviduct. Two to three days after the LH peak, the oocytes reach the metaphase of the first meiosis and after three to five days the metaphase of the second meiosis, with the expulsion of the first polar body. According to Verstegen et al. (2001), canine oocytes may remain fertilizable for more than 200 hours.

After fertilization, the embryos go through the cleavage period (cell division) of the blastomeres and reach the uterus around day 11. However, between the 12th and 13th days after the first embryos at various stages of development can be found inside the uterus, since zygotes to blastocysts erupted. According to Concannon et al. (2001), in females at embryonic cleavage between the stages of two and 16 cells is faster after fertilization of more oocytes when compared to less mature oocytes, and this could explain why the duration of gestation is similar when copulation occurs before or several days after oocyte maturation.

Before the implantation, in approximately 50% of the female dogs, the embryos go through an event. called transcranial migration. This phenomenon occurs between days 12 and 16-18 of pregnancy. According to these authors, the objective is to the main feature of this migration is the equitable distribution of embryos between the two uterine horns. Between the 19th and 20, some proteins linked to embryonic implantation are secreted by embryos, such as proteins canines 1, 4, 6 and 7 (cP1, cP4, cP6, and cP7), and are similar to endometrium secreted proteins. On the other hand, the protein cP7 is only secreted by blastocysts prior to implantation. Implantation embryonic begins around days 16 to 18 and is completed until day 23 of pregnancy, being observed that between the 22nd and 23rd there is an invasion of the placental trophoectoderm into the endometrium. 


Related Posts
Disqus Comments