How Long Are Horses Pregnant? Gestation, Foaling Signs and the First Hours

Horse gestation is genuinely more variable than most other backyard species, and foaling has its own detailed timeline of physical signs. This guide draws on Oklahoma State University Extension's foaling management guidance, and is general information rather than a substitute for your vet.

Gestation: 320 to 380 days, averaging 338 to 345

Oklahoma State University Extension gives a normal range of 320 to 380 days, with most mares averaging 338 to 345 days. That range is genuinely wider than other species on this site — day length, the mare's age and her prior foaling history all affect it, and gestation length alone isn't a reliable way to judge whether a foal is ready to be born. A predictor of 335 days after the last breeding date is commonly used, deliberately a little shorter than the average to allow extra watching time before most mares foal. Our due-date calculator shows the expected date alongside an earliest and latest date to reflect that width.

The signs that foaling is approaching

Extension guidance lists a detailed timeline, though not every mare shows every sign, and signs vary between mares and between pregnancies. The udder begins filling 2 to 4 weeks before foaling. Conformational changes — the tailhead muscles relaxing, the abdomen dropping — start 1 week to 1 month prior. Teats fill with milk 2 days to 1 week before, sometimes with visible dripping. “Waxing” — wax-like beads of colostrum forming on the teat ends — typically happens 1 to 4 days before. The external genitalia relax in the final half-day to full day.

Mammary secretion calcium testing gives the most precise prediction available: a calcium concentration above 200ppm gives roughly a 54% chance of foaling within 24 hours, rising to 84% within 48 hours and 97% within 72 hours — test kits for this are available through vets.

Foaling: three stages

Stage one begins with contractions and usually lasts 1 to 2 hours — the mare becomes anxious and restless, may appear mildly colicky, and often paces, lies down and gets up repeatedly. This stage ends when the amniotic sac breaks. Contact a vet if this stage runs more than an hour or two without progress.

Stage two is the actual delivery, usually complete within 15 to 20 minutes of the water breaking — taking more than 30 minutes may need intervention. A normal foal presents front feet first, hooves down, followed by the nose and head; hooves pointing up means the foal may be positioned wrong, and a vet should be called immediately.

Stage three is passing the placenta, usually within 1 to 3 hours after the foal is born. Call a vet if it hasn't passed within 3 hours — a retained placenta can cause serious infection.

The first hours of a foal's life

Extension guidance gives clear benchmarks: a foal should attempt to stand within 60 minutes (over 2 hours may signal a problem) and nurse within 2 hours (over 3 to 4 hours is considered abnormal). Nursing matters more than it might seem — the first milk carries antibodies essential to the foal's immune system, and delayed nursing past 8 to 12 hours meaningfully impairs that antibody transfer.

Before you breed

A foal doesn't just add a horse — our companionship guide already covers why horses shouldn't be kept alone, and Oklahoma State's guidance notes that even a small goat has been used successfully as a companion for an orphan or weaning foal when another horse isn't available. Use plan my setup to model space and cost for the numbers you'll actually have.

Source: Oklahoma State University Extension, “Foaling Management and Care of the Nursing Foal” (AFS-3985, published November 2024) by Reed Holyoak and Kris Hiney: extension.okstate.edu. Sources checked: September 2026. General information, not veterinary advice.

Common questions

How long is a horse pregnant?

Oklahoma State University Extension gives a normal range of 320 to 380 days, with an average of 338 to 345 days — genuinely wider natural variation than most other backyard species, affected by day length, the mare's age and her prior foaling history.

What is 'waxing' in a pregnant mare?

Waxing is when wax-like beads of colostrum form on the ends of the teats, typically 1 to 4 days before foaling. It's one of several signs used to predict foaling day, alongside udder filling (2 to 4 weeks prior) and changes in milk mineral content.

How long does foaling take?

Stage one (contractions and positioning) usually lasts 1 to 2 hours. Stage two, the actual delivery, usually takes 15 to 20 minutes once the water breaks — over 30 minutes may need intervention. Stage three, passing the placenta, usually happens within 1 to 3 hours after the foal is born.

How soon should a foal stand and nurse?

Oklahoma State University Extension gives 60 minutes as the normal time to stand (over 2 hours may signal a problem) and 2 hours as the normal time to nurse (over 3 to 4 hours is considered abnormal).