Endoscopic transcervical intrauterine artificial insemination in Labrador Retriever bitches

Factors Affecting Pregnancy Success in the Bitch Following Transcervical Insemination

Endoscopic-assisted transcervical inseminations (TCIs) have become increasingly popular. The aim of this retrospective clinical study was to evaluate data from the TCIs performed at our facility. We evaluated data from January 2018 through December 2021. This included 137 cases with fresh, 67 cases chilled, and 63 cases using frozen-thawed semen. All bitches underwent breeding management to determine the ideal breeding period. All semen samples were evaluated for total number of sperm, total motility, and progressive motility. Pregnancy was determined by B-mode ultrasonography about 4 weeks after the breeding. Litter size was determined by radiographs performed around the last week of gestation. The pregnancy rate was 83.21% for fresh, 67.16% for chilled, and 66.67% for frozen-thawed semen. There was a significant difference in litter size between fresh semen (6.82 puppies per litter) and both chilled (5.21 puppies per litter) and frozen-thawed (4.59 puppies per litter) semen (P < .05). There was no significant difference in litter size between chilled and frozen-thawed semen. There was no difference in pregnancy rates between clinicians performing the inseminations. Pregnancy rate was not different when sedation was used for the insemination (66.67%) compared to when sedation was not used (74.84%; P > .05). Performing 2 TCIs during the fertile period, regardless of the semen type, resulted in an increase of 6.6% in pregnancy rate (P > .05) and an increase of 0.7 puppies per litter, on average (P > .05). These results can be used to help guide recommendations for breeding clients on the best options to increase both pregnancy rate and litter size for their breeding.

In vivo embryo development in bitches inseminated laparoscopically after ovulation time estimated based on a single progesterone determination

Logistic and economical limitations are often the causes of dog owners not accurately monitoring the estrous cycle and the optimal insemination time. The aim of this study was to evaluate in vivo early embryonic development in bitches, after the analysis of sequential vaginal cytologies associated to single progesterone measurement and single laparoscopic insemination with high quality semen (fresh and with high spermatozoa concentration) or low-quality semen (frozen/thawed and with low spermatozoa concentration) at 48 h post- ovulation time predicted on a single progesterone measurement. Ten bitches were inseminated with 250 x 10⁶ fresh spermatozoa (80% motility), and ten with 80 x 10⁶ frozen/thawed spermatozoa (60% motility) in the cranial part of each uterine horn. Seven days later, ovariohysterectomy was performed and the oviducts and uterine horns and body were flushed to recover embryos and unfertilized oocytes. In 80% of the bitches inseminated with fresh and 50% of bitches inseminated with frozen/thawed semen, embryos at 2 to 8 cells stage were recovered mostly from the, oviducts. This study indicates that pregnancies can be obtained with a single laparoscopic intrauterine insemination after single serum progesterone measurement, although with a low number of embryos. This result should be taken into account in case economic or logistic restrictions that affect the possibility of owners to plan an accurate monitoring of the optimal breeding time using fresh and frozen semen.