Birth of puppies after intrauterine and intratubal insemination with frozen-thawed canine semen.

The present study was performed to assess the fertility of frozen-thawed dog semen prepared by freezing with 6% glycerol and thawing at 70 degrees C for 8 sec, and to evaluate the least number of post-thaw spermatozoa necessary to achieve pregnancy by intrauterine or intratubal artificial insemination. It was found that the pregnancy rate of intrauterine artificial insemination was 100% using 6% glycerol buffer and thawing at 70 degrees C for 8 sec with 5 x 10(7) spermatozoa. Even though the pregnancy rate (80%) and the whelping rate (24.5%) in the 5 x 10(6) spermatozoa inseminated group were lower than those of the 5 x 10(7) spermatozoa group, conception was confirmed with 5 x 10(6) spermatozoa. Although the pregnancy rate of intratubal insemination was low (20%) with 4 x 10(6) spermatozoa, this study is the first report to show the pregnancy rate of intratubal insemination with frozen-thawed ejaculated canine semen. In order to improve the pregnancy rate with intratubal insemination of canine spermatozoa, it is necessary to investigate the optimal insemination site of the uterine tube, the appropriate number of sperm, and the direct effect of buffer on oocytes.