Okkens A C, Teunissen J M, Van Osch W, Van Den Brom W E, Dieleman S J, Kooistra H S
Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, University of Utrecht, PO Box 80.154, 3508 TD Utrecht, The Netherlands.
J Reprod Fertil Suppl. 2001;57:193-7.
The variation in the duration of gestation, defined as the period from mating to parturition, was studied in 113 bitches of six breeds (31 Dobermans, 31 Labrador retrievers, 14 German shepherds, 13 Bernese mountain dogs, 12 golden retrievers and 12 West Highland white terriers). The bitches were mated once on the optimal day for mating, which was established by measuring the plasma concentration of progesterone. The duration of gestation varied between 58 and 65 days with a mean of 61.4 +/- 1.5 days (+/- SD). The mean duration of gestation in West Highland white terriers (62.8 +/- 1.2 days) was significantly longer than that of German shepherds (60.4 +/- 1.7; P < 0.001), Labrador retrievers (60.9 +/- 1.5; P < 0.001) and Dobermans (61.4 +/- 1.0; P < 0.025). The variation in the duration of gestation in any one of the six breeds was low, ranging from 4 to 7 days, or less when litters of one pup (n = 4) were excluded. The number of pups per litter varied between one and 15 with a median of eight pups. In the total population, the duration of gestation was negatively correlated with litter size (r = -0.73; P = 0.005) for litters (n = 112) containing < or = 13 pups. However, within each breed multiple regression analysis failed to show any influence of litter size on the duration of gestation. The median litter size of different breeds and the mean duration of gestation were negatively correlated (r = -0.78; P = 0.03; n = 6). Therefore, although it was not conclusively proven, the results indicate that the breed is a major determinant of the duration of gestation in bitches and that the influence of breed may be ascribed to breed-related differences in litter size.
妊娠期定义为从交配到分娩的时间段，对6个品种的113只母犬进行了妊娠期时长变化的研究（31只杜宾犬、31只拉布拉多寻回犬、14只德国牧羊犬、13只伯恩山犬、12只金毛寻回犬和12只西部高地白梗）。母犬在通过测量孕酮血浆浓度确定的最佳交配日进行一次交配。妊娠期时长在58至65天之间，平均为61.4±1.5天（±标准差）。西部高地白梗的平均妊娠期时长（62.8±1.2天）显著长于德国牧羊犬（60.4±1.7天；P<0.001）、拉布拉多寻回犬（60.9±1.5天；P<0.001）和杜宾犬（61.4±1.0天；P<0.025）。六个品种中任何一个品种的妊娠期时长变化都很小，范围在4至7天，若排除单胎幼犬的窝（n = 4），则变化更小。每窝幼犬数量在1至15只之间，中位数为8只幼犬。在总群体中，对于包含≤13只幼犬的窝（n = 112），妊娠期时长与窝仔数呈负相关（r = -0.73；P = 0.005）。然而，在每个品种内，多元回归分析未显示窝仔数对妊娠期时长有任何影响。不同品种的窝仔数中位数与平均妊娠期时长呈负相关（r = -0.78；P = 0.03；n = 6）。因此，尽管未得到确凿证明，但结果表明品种是母犬妊娠期时长的主要决定因素，且品种的影响可能归因于与品种相关的窝仔数差异。
