New data on progesterone levels and the limits of the fertile period in dogs

Abstract

Purpose: to clarify the possibility of pregnancy in dogs with blood progesterone levels above 20 ng/ml.

Materials and methods. The study was conducted in the period from January 2018 to May 2022. The study involved 25 females of various breeds aged from 1.5 to 8 years. The progesterone level of peripheral blood was analyzed, taken into vacuum tubes using a butterfly needle with a size from 20G to 23G, the size of the needle section was selected depending on the thickness of the anterior subcutaneous vein of the forearm, from which samples were taken. Blood sampling for progesterone is performed immediately before insemination. Samples were sent to the veterinary laboratories of NVL Poisk (St. Petersburg) and Vetdiagnostic (St. Petersburg). The study was performed by immunochemiluminescence analysis (IHLA) on an IMMULITE 2000 XPi analyzer (Siemens Healthcare Diagnostics). The number of female litter was taken into account during insemination at a progesterone level of more than 20 ng/ml.

Results. Four bitches out of 25 participating in the study were successfully inseminated once at a progesterone level in peripheral blood ≥ 21 ng/ml. 3 bitches out of 25 did not get pregnant for unknown reasons, 18 bitches were in the study area 15-20 ng/ml and did not fit the specified sample parameters. A multiple pregnancy was recorded in a four-year-old German Shepherd with a single insemination at a progesterone level of 45 ng/ml, which is one of the highest recorded results for today.

Conclusion. When inseminating dogs at a progesterone level of 21-45 ng/ ml, multiple pregnancies may occur in dogs of various breeds aged from 1.5 to 8 years.