Department of Veterinary Sciences, University of Pisa, 56122, San Piero a Grado, Pisa, Italy.
Department of Veterinary Sciences, University of Pisa, 56122, San Piero a Grado, Pisa, Italy.
Theriogenology. 2020 Jan 1;141:1-8. doi: 10.1016/j.theriogenology.2019.08.017. Epub 2019 Aug 20.
Puppy neonatal mortality may be related to low birth weight, which has been shown in humans to be linked to placental factors. The relation between the newborn puppy and the placental characteristics has been poorly investigated in dogs. Twenty bitches, 9 toy-sized (i.e. < 5 Kg) and 11 small-sized (i.e. 5 to 10 Kg), were included in this study. During natural delivery or c-section, puppies were identified and their order of birth, sex and weight were recorded. Puppy weights were registered at birth and daily until Day 6. Placentas were weighed after removal of extraplacental adnexa, after which a photo was taken and morphometrically assessed. The Total Placental Area (TPA) and the Transfer Zone Area (TZA) were calculated and their surface expressed in mm. Immunohistochemistry with monoclonal mouse anti CD31 antibody was used to identify fetal and maternal vessels in the placental labyrinth zone. A vascularization index (VI) was determined for each placenta and the Total Vascular Area (TVA) was estimated. Puppies' birth weight correlated positively with placental weight (P < 0.001, r = 0.689). A positive correlation was found between the puppies' birth weight and TPA (P < 0.001, r = 0.786), TZA (P < 0.001, r = 0.772), and TVA (P < 0.001, r = 0.482). A positive correlation was also found between placental weight and TPA (P < 0.001, r = 0.661), TZA (P < 0.001, r = 0.583), and TVA (P < 0.001, r = 0.333). In the small-sized breeds, the placentas of low-weight puppies were lighter and had a smaller TZA and TVA (P < 0.05). The VI was higher in the placentas of the toy-sized compared to small-sized bitches (P < 0.01). No effect of parity, litter size, or sex of the puppy was observed on birth weight or growth rates on Day 6. The growth pattern of low-weight puppies did not differ from that of the other puppies during the first 6 days of life. As in humans, placental weight, the extension of the transfer zone and placental total vascular area correlates closely with the puppies' birth weight in normal pregnancies. Our data could represent reference values for placental weight, TZA, TVA and VI in toy and small-sized dog breeds.
幼犬新生仔死亡率可能与低出生体重有关，这在人类中已被证明与胎盘因素有关。犬的新生幼犬与胎盘特征之间的关系尚未得到充分研究。本研究纳入了 20 只母犬，9 只为玩具犬（即 < 5kg），11 只为小型犬（即 5-10kg）。在自然分娩或剖宫产过程中，记录了幼犬的出生顺序、性别和体重。幼犬在出生时和出生后第 6 天前每天称重。胎盘在去除胎盘附件后称重，然后拍照并进行形态学评估。计算总胎盘面积（TPA）和转移区面积（TZA），并以毫米表示其表面积。使用单克隆鼠抗 CD31 抗体进行免疫组织化学染色，以识别胎盘绒毛膜区的胎儿和母体血管。确定每个胎盘的血管化指数（VI），并估计总血管面积（TVA）。幼犬的出生体重与胎盘重量呈正相关（P<0.001，r=0.689）。幼犬的出生体重与 TPA（P<0.001，r=0.786）、TZA（P<0.001，r=0.772）和 TVA（P<0.001，r=0.482）呈正相关。胎盘重量与 TPA（P<0.001，r=0.661）、TZA（P<0.001，r=0.583）和 TVA（P<0.001，r=0.333）也呈正相关。在小型犬中，低体重幼犬的胎盘较轻，TZA 和 TVA 较小（P<0.05）。与小型犬相比，玩具犬的胎盘 VI 更高（P<0.01）。幼犬的出生体重或第 6 天的生长速度不受产次、窝产仔数或性别影响。低体重幼犬在生命的前 6 天的生长模式与其他幼犬没有差异。与人类一样，在正常妊娠中，胎盘重量、转移区的延伸和胎盘总血管面积与幼犬的出生体重密切相关。我们的数据可为玩具犬和小型犬种的胎盘重量、TZA、TVA 和 VI 提供参考值。
