PMSG is a complex glycoprotein obtained from the serum of pregnant mares. This 43-63 kda protein is capable of supplementing and being substituted for the follicle stimulating and interstitial cell-stimulating hormone of the anterior pituitary gland in both the male and female. Thus PMSG-Intervet stimulates development of the ovarian follicle in the female.

PMSG Hormone is a well known hormone used together with progestogen to increase ovulation just before to artificial insemination. PMSG hormone is a placental glycoprotein produced from the serum of pregnant mares. PMSG comprises of an alfa subunit and a beta subunit. PMSG hormone is secreted from endometrial cups within the pregnant mare uterus aging from 40 to 130 days into their maturation, and once extracted, it can been used to promote artificially estrus in female animals. These assemblies produce PMSG hormone to induce mare's ovarian and repsouctive structures. PMSG can induce the growth of follicles by ovaries and results in ovulatation. PMSG hormone has an about a 4 day half-life of bioactivity in species other than horses. The extended biological activity can cause ovarian stimulation and ovulation. However, PMSG use alone often causes cystic ovarian disease because of the unrestrained ovarian stimulation and due to the sugar molecules which decrease clearance of the hormone. PMSG is more likely to be used than other pituitary hormones due to the extended circulatory half-life. PMSG solely exhibits luteinizing hormone like activity, however in other animal classes it has FSH & LH like activity.