📋 At a Glance
Pre-breeding examBreeding soundness examination by a reproductive veterinarian before each breeding season — not optional for serious programs
EHV-1 vaccinationRhinopneumonitis at months 5, 7, and 9 of gestation — reduces EHV-1 abortion risk
Pre-foaling vaccinesCore vaccines 4–6 weeks before expected foaling — maximizes antibody levels in colostrum for foal
GestationAverage 340 days (range 320–370) — considerable individual variation; mares often foal at consistent relative times year to year
Foal heatMares typically cycle 7–10 days after foaling — foal-heat breeding is possible but not ideal; discuss with reproductive vet
Retained placentaMust be passed within 3 hours of foaling — after 3 hours, call your veterinarian; do NOT pull it
Colostrum qualityBrix refractometer test (>23% = good quality); can be tested before foaling; have backup plan if poor
⚠️ Breeding Mare Emergencies — Call Immediately
- Placenta not passed within 3 hours of foaling — retained placenta is a serious emergency causing endotoxemia and laminitis
- Excessive hemorrhage during or after foaling
- Colic signs in a pregnant mare — uterine torsion possible
- Foal not delivered within 30 minutes of the amniotic sac rupturing (active stage 2 labor) — dystocia emergency
- Severe ventral edema late in pregnancy making walking difficult — possible rupturing prepubic tendon
- Prolapsed uterus after foaling — uterine tissue visible at the vulva; immediate emergency
- Mare recumbent and unable or unwilling to rise in late pregnancy or immediately postpartum
Pre-Breeding Examination — The Foundation
A pre-breeding examination by a licensed equine reproductive veterinarian is the most important proactive step in a breeding program. The exam evaluates everything that determines whether this mare is likely to conceive and maintain a pregnancy: vulvar conformation, uterine health, ovarian activity, and the presence of subclinical endometritis that would prevent implantation or cause early embryonic death.
| Exam Component | What Is Assessed | Why It Matters |
|---|---|---|
| Perineal conformation (Caslick's assessment) | Angle of the vulva; degree of pneumovagina risk | Poor conformation allows fecal contamination of the reproductive tract; Caslick's procedure corrects this surgically |
| Rectal palpation and ultrasonography | Uterine tone, echotexture, fluid accumulation; ovarian size and follicle development | Identifies endometritis, cysts, uterine pathology before breeding; monitors follicle to time breeding |
| Uterine culture and cytology | Bacterial culture for pathogens; cytology for inflammatory cells | Identifies subclinical endometritis that prevents conception; guides antibiotic selection if needed |
| Uterine biopsy (selected mares) | Histological assessment of endometrial health | Categorizes endometrial health (Grade I–III); provides prognosis for carrying a foal to term |
| Hormone assessment | Progesterone levels; may be used to confirm luteal function | Ensures mare is cycling normally and corpus luteum function is adequate |
Vaccination During Pregnancy — Timing Is Everything
Vaccination timing during pregnancy is not arbitrary — it directly determines two outcomes: EHV-1 abortion prevention (months 5, 7, and 9 of gestation), and the immune protection the foal receives through colostrum (core vaccines 4–6 weeks before foaling). Getting the timing right requires knowing the mare's breeding date and calculating accordingly.
| Vaccine | Timing | Purpose | Important Note |
|---|---|---|---|
| EHV-1 (Rhinopneumonitis) | Months 5, 7, and 9 of gestation | Reduce EHV-1 abortion risk — a significant cause of late-term pregnancy loss | Killed products only during pregnancy; NO modified live EHV vaccines in pregnant mares |
| EEE/WEE, Tetanus, West Nile | 4–6 weeks before expected foaling date | Maximizes IgG levels in colostrum — the foal's immune foundation | Timing to foaling maximizes antibody transfer; too early = lower colostrum antibody levels |
| Influenza | 4–6 weeks before foaling | Same colostrum transfer strategy | Confirm product is labeled for use in pregnant mares |
| Rabies | Annually — time to 4–6 weeks pre-foaling if due | Annual requirement; colostrum transfer strategy | Confirm product safety in pregnancy with your vet |
| Botulism | Discuss with vet — endemic areas | Foal protection through colostrum in high-risk regions (Kentucky, parts of Southeast) | First trimester if not previously vaccinated |
Recognizing Pre-Foaling Signs
Foaling preparation begins 2–4 weeks before the expected date. Recognizing the signs of impending parturition allows appropriate monitoring — particularly important because most mares foal at night and the active delivery stage (stage 2) lasts only 20–30 minutes. A foal not delivered within 30 minutes of the amniotic sac rupturing is a dystocia emergency.
| Sign | Typical Timing Before Foaling | Notes |
|---|---|---|
| Udder development | 2–4 weeks before | Progressive filling; check daily once development begins |
| Waxing (dried colostrum on teats) | 12–48 hours before | Not universal — some mares wax; some don't; some have already leaked colostrum |
| Milk let-down | Hours before | Colostrum freely running from teat — foaling typically within 12 hours |
| Perineal relaxation | 24–48 hours before | Vulva, tailhead, and pelvic musculature visibly soften and relax |
| Restlessness and mild colic signs | Hours to minutes before | Uterine contractions beginning; mare may circle, look at flank, lie down and get up |
| Sweating | Just before active labor | Particularly around flank and behind ears |
Stage 1, 2, and 3 of Parturition — Know What's Normal
- Stage 1 (preparatory): uterine contractions, restlessness, sweating, colic-like signs. Duration: 1–4 hours. Mare may stand and lie repeatedly. No reason to intervene.
- Stage 2 (active delivery): rupture of the chorioallantois ('water breaking'); active abdominal straining; foal delivered. Duration: 20–30 minutes. Longer than 30 minutes without progress = call vet immediately.
- Stage 3 (placental expulsion): placenta passed. Should occur within 1–3 hours of foaling. After 3 hours without passage = call vet. Do NOT pull the placenta.
Post-Foaling Monitoring
The 24 hours after foaling are critical for both mare and foal. The mare needs monitoring for retained placenta (>3 hours), excessive hemorrhage, uterine prolapse, and post-partum colic. The foal needs IgG testing at 18–24 hours and monitoring per the foal health protocol.
Document the placenta after it passes: lay it out in a Y-shape and examine for completeness — any missing horn piece means retained tissue and requires immediate veterinary contact. Retained placental tissue causes endotoxemia and laminitis that can be severe and rapid in onset.
✅ Breeding Mare Annual Health Program
- Pre-breeding exam 4–6 weeks before the planned breeding date — culture, cytology, and ultrasonographic assessment
- Confirm EHV vaccination timing — calculate months 5, 7, and 9 from the breeding date and schedule accordingly
- Time core vaccines 4–6 weeks before the expected foaling date — not earlier, not later
- Test colostrum quality before foaling if possible — Brix refractometer; have backup plan (banked colostrum or replacer)
- Have veterinarian's emergency foaling number saved and accessible before foaling season begins
- Document the placenta after passage — photograph and examine for completeness
📋 Breeding Mare Discussion Points for Your Vet
- Caslick's procedure — does this mare's perineal conformation warrant suturing before breeding, and when should it be opened
- Uterine culture results — if endometritis is present, treatment before breeding rather than after repeated failures
- Post-breeding uterine management — 'problem mares' benefit from post-breeding uterine lavage to remove fluid accumulation
- Twin pregnancy management — if twins detected at day 14–16 ultrasound, early manual reduction before day 16 is the preferred approach
- Neonatal isoerythrolysis (NI) risk — mares with type A or Q blood factors can produce antibodies destroying foal red cells; testing available
- Foaling monitoring protocol — in-stall camera, foaling alarm, attendant protocol based on facility resources
Questions to Ask Your Veterinarian
- Based on this uterine culture, what endometritis treatment do you recommend before breeding?
- Does this mare's conformation warrant a Caslick's procedure, and if so, when should I plan to have it opened?
- What is the precise EHV vaccination schedule based on this mare's breeding date?
- What colostrum quality threshold should I be targeting, and what is the backup plan if quality is inadequate?
- Is this mare a candidate for twin pregnancy based on history or ultrasound findings?
- What is your preferred retained placenta protocol — when and how should I treat it if the placenta isn't passed?
🐴 Breeding Mare
Proactive Horse Care — Annual Health Planning
Julie Goodnight
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