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.