|Sample Requirement||Turnaround Time|
|Serum or heparin|
Same working day
The analysis of plasma progesterone levels is a useful guide to diagnosis and treatment in the acyclic or irregularly cyclic mare. In the non-pregnant mare, levels >2 ng/l (6.3 nmol/l) indicate functional luteal tissue and suggest that prostaglandin treatment should induce luteolysis, providing that the corpus luteum is more than 4 days old.
In the pregnant mare, there is no proven relationship between progesterone levels and the integrity of pregnancy. Mares with levels <2 ng/ml are unlikely to be pregnant. Most normally pregnant mares have levels >4 ng/ml but there is considerable daily and individual variation. The progesterone assay is in no way an accurate pregnancy test but may be helpful, or reassuring to managers, in monitoring individual mares with histories of repeated pregnancy failure.