Fertility in dogs in relation to semen quality and the time and site of insemination with fresh and frozen semen
Linde-Forsberg, C.; Forsberg, M.
Journal of Reproduction and Fertility. Supplement 39: 299-310
1989
ISSN/ISBN: 0449-3087 PMID: 2621732 Document Number: 335516
470 bitches were inseminated, 405 with fresh semen into the cranial vagina and 65 with frozen semen transcervically into the uterus. The pregnancy rate was 65.7% with fresh semen and 41.5% with frozen semen. When corrected for stage of oestrus at the time of insemination and for semen quality, the pregnancy rate was 83.8% with fresh semen and 69.3% with frozen semen. It improved with an increase in the number of inseminations. Inseminations with fresh semen before the time of ovulation (<17.3 nmol progesterone/litre) were often successful. With frozen semen, the peripheral plasma progesterone concentration at the time of insemination was >30 nmol/litre in all but 1 of the bitches that became pregnant. This difference was assumed to be attributable to a longer survival time of several days for fresh semen than for frozen-thawed semen. Cytological scoring was a satisfactory method for determining the stage of oestrus when using fresh semen, but more precise methods were needed when using frozen semen. Semen quality was difficult to correlate with fertility. Pregnancy was obtained with fresh semen of inferior quality, although the litter size was smaller than when better quality semen was used. With frozen semen, no pregnancies resulted when the semen quality was poor. Litter size was estimated to be 21.5% smaller in bitches inseminated with fresh semen than in naturally mated bitches. Litter size in bitches inseminated with frozen semn was 23.3% smaller than in bitches inseminated with fresh semen. Pup death occurred in 35.5% of the litters in this study. The overall mortality during the first 3 wk of life was 11.9%. Although not significant, there was a tendency for bitches treated with antibiotics at the time of mating or during early pregnancy to have a higher pregnancy rate and a larger litter size than untreated bitches.