🐴 Horse Pregnancy Due Date Calculator
Calculate your mare’s foaling date from the breeding date. Average equine gestation: 340 days (~11 months).
Horse (Mare) Pregnancy Due Date Calculator
Equine Gestation Guide
Horse pregnancy is one of the longest domestic animal gestations, lasting approximately 11 months. The wide normal range (320–362 days) means foaling can occur more than 3 weeks before or after the average. Understanding this range is critical for planning foaling surveillance and veterinary care.
Unlike many other species, equine gestation length is influenced by season. Mares bred in late spring or summer tend to have shorter pregnancies than those bred in fall or winter. This is linked to photoperiod (day length) affecting hormone regulation. Draft breeds tend toward longer gestations than Thoroughbreds and Arabians.
Key Milestones in Equine Pregnancy
| Timepoint | Event |
|---|---|
| Day 14–16 | Ultrasound can confirm pregnancy (embryonic vesicle) |
| Day 25–30 | Heartbeat visible on ultrasound |
| Day 42 | Endometrial cups form (eCG production begins) |
| Day 120 | Critical placental transition complete |
| Month 7–8 | Rapid fetal growth; mare's belly noticeably large |
| Day 320+ | Begin foaling watch |
| Day 340 | Average foaling date |
Frequently Asked Questions
Common questions answered by our medical team