Serum kisspeptin levels in pregnant and non-pregnant diestrus bitches: a pilot study

Kisspeptins are neuropeptides that play a key role in regulating reproductive function. They are also involved in maternal-fetal communication and the development of the placenta in several mammalian species. In humans and cattle, circulating kisspeptin concentrations increase during pregnancy, and the placenta has been proposed as their main source of production. To the best of the authors’ knowledge, no data are currently available regarding serum kisspeptin concentrations during canine pregnancy. The aim of this study was to evaluate, for the first time, serum kisspeptin concentrations in pregnant bitches compared with non-pregnant diestrus bitches. Eight clinically healthy German Shepherd bitches were enrolled and divided into two groups: pregnant (n = 4) and non-pregnant diestrus (n = 4). Blood samples were collected from ovulation and every 15 days until the end of pregnancy or diestrus. Pregnancy was diagnosed using ultrasonography at 19 days post-ovulation and was monitored simultaneously with blood sampling. Median serum kisspeptin concentrations throughout the observation period tended to be higher in pregnant bitches, with a statistically significant difference between groups observed on Day 15 post-ovulation (p = 0.029). This early increase in serum kisspeptin concentrations suggests that kisspeptin circulating in the bloodstream deserves further investigation as a potential biomarker for the early detection of pregnancy in bitches. However, these findings should be interpreted with caution given the exploratory nature of the study and its small sample size.