Platelet Aggregation Percentage Increased in Healthy Broodmares During the Peripartum

The aim of our study was to investigate whether the peripartum has any influence on platelet aggregation in the mare to characterize the role of platelets in mare's normal pregnancy. Ten healthy pregnant Italian Saddle broodmares were monitored during the peripartum (from 2 weeks before until 2 week after foaling). Blood samples were collected at 7-day intervals, except the first postfoaling sample collected within 24 ± 12 hours from parturition. A pool of 26 blood samples from nonpregnant, nonlactating mares was used as control. The obtained samples were tested for platelet aggregation using adenosine diphosphate as agonist. Significant differences (P = .0002) were found between pregnant and control mares. The percentage of platelet aggregation increased significantly in pregnant mares starting 2 weeks before parturition. Our results support the hypothesis that a physiologically adaptive mechanism occurs in healthy periparturient broodmares to prevent excessive blood loss from damaged vessels at the time of delivery.