Artificial insemination with frozen semen in dogs: A retrospective study of 10 years using a non-surgical approach

Abstract

From 1994 to 2003, a total of 526 bitches of 99 different breeds were artificially inseminated in 685 estrus cycles with domestic ( n = 353) or imported ( n = 332) frozen-thawed semen from 368 males. The overall whelping rate was 73.1% and mean (±S.E.M.) litter size 5.7 ± 0.1 pups. The whelping rate was higher after intrauterine insemination (75.0%; n = 665) than after intravaginal insemination (10.0%, n = 20; P < 0.05). Insemination at the optimal time resulted in a higher whelping rate (78%, n = 559; P < 0.01) and larger litter size (5.8 ± 0.2; P < 0.05) than inseminations performed late or too late (55.7% and 4.5 ± 0.5, n = 61). Two inseminations ( n = 384) yielded a higher whelping rate ( P < 0.05) and mean litter size ( P < 0.01) than one insemination ( n = 241), 78.1% and 6.0 ± 0.2 and 70.5% and 5.1 ± 0.2, respectively. For inseminations performed at the optimal time, however, the whelping rate was not significantly different for bitches inseminated twice (79.3%, n = 358) versus once (76.8%, n = 168), but the litter size was larger (6.0 ± 0.2 and 5.3 ± 0.3). Semen classified as of poor quality (progressive motility <50% or percentage abnormal sperm >20%) resulted in a lower whelping rate ( P < 0.01) than semen classified as of good quality (progressive motility ≥50% and percentage abnormal sperm ≤20%), 61 and 77%, respectively. Small breeds ( n = 50) had a smaller litter size (3.9 ± 0.3; P < 0.01) than larger breeds (medium [5.7 ± 0.3, n = 94], large [5.9 ± 0.2, n = 295] or giant breeds [6.1 ± 0.5, n = 62] [ P < 0.01]). Bitches older than 6 years had a lower whelping rate (68.2%) than younger ones (77.0%; P < 0.05). The duration of pregnancy was longer ( P < 0.01) for bitches with a litter size of <3 pups (61.7 ± 0. 4 days, n = 30) than for bitches with larger litters (60.5 ± 0.1 days, n = 177). These results show the potential of transcervical intrauterine insemination for routine artificial insemination in dogs. The results with frozen semen inseminations were optimised by inseminating bitches ≤6 years old 2 and 3 days after ovulation with semen of good quality from males ≤8 years old.