Efficient timed mating and early pregnancy detection in guinea pigs v1

Guinea pigs have served as valuable animal models for various research questions. The structural similarity of the guinea pig placenta to the human placenta, particularly its hemomonochorial organization, supports its use in reproductive and developmental research. Yet, timed mating and early pregnancy detection remain significantly more challenging compared to mice, and many procedures are not standardized. Here, we present a comprehensive protocol to improve mating efficiency using vaginal impedance and cytology examination for overnight matings, and to enable pregnancy detection using ultrasound as early as embryonic developmental day (E) 12.