Although canine oocytes are released in immature stages, canine spermatozoa retain their fertilizing capacity for about 5 days and the duration of the mating period until the conception is long, about 7 days. However, when the mating or artificial inseminations are performed too early or too late of the follicular phase of the estrous cycle fertilization rates can be reduced.
This study investigated the efficiency of the protocol of artificial insemination (AI) taking into consideration only the vaginal cytology.
For this experiment, 10 bitches were used in the initial phase of proestrus, monitored daily by vaginal cytology until they showed 80% or more superficial cells. Then, the animals were inseminated three times every 48 hours intravaginally. After 12 days of first A.I. bitches were submitted to ovariohysterectomy. The uterus was isolated, the uterine horns were separated and the uterine flushing was performed with PBS solution directly into Petri plates for evaluation and identification of embryonic structures.
After uterine flushing, 63 embryos were recovered (54 blastocysts and nine morulae). A total of 81 corpora lutea were identified, totaling an embryo recovery rate of 77.78%.
This insemination protocol using only the vaginal cytology proved to be practical, efficient and viable for studies of embryonic development.