An immunochemical demonstration of a pregnancy-specific protein in the horse and its use in the serological detection of early pregnancy.

This research article details the identification of a protein specifically found in pregnant horses. The presence of this protein could potentially serve as an early indicator of successful pregnancy following mating between a mare and a stallion.

Research methods and findings

• The research involved two-dimensional crossed immunoelectrophoresis of sera from both pregnant and non-pregnant horses.
• Antisera developed against early pregnant mare serum were used in the process.
• Two proteins were detected in this way. The first appeared to be specific to pregnancy, while the second was found in both pregnant and non-pregnant horses.
• These proteins were respectively named beta 2-horse pregnancy protein and gamma 2-horse protein. The former was first visible at Day 6 post successful mating, whereas the latter was ever-present irrespective of the mare’s pregnancy status.
• Samples from 16 mares mated with a stallion were analyzed to track the presence of the beta 2-protein within the first 3 weeks after mating.
• Of the 11 successful matings, which stood confirmed using ultrasonic scanning at 90 days or by a successful outcome, the protein was present in 10 mares.
• In contrast, none of the 14 samples from non-pregnant mares not recently mated showed any trace of the protein.

Statistical significance and potential implications

• The study indicates that the detection of beta 2-protein possesses clinical significance as an early sign of pregnancy at the 10% level.
• Interestingly, the presence of the protein in 2 of the 5 mares that mated recently but did not become pregnant, might suggest a biochemical pregnancy that failed at a later point of gestation.
• Such a finding could potentially have implications in equine reproduction, particularly in the objective of detecting early pregnancies.