How it works
Most livestock come back into heat on a steady rhythm: about every 21 days for goats, cattle, pigs and horses, and about every 17 days for sheep. If you write down one heat, you can predict the next ones and be ready to breed, or confirm she settled when no heat shows up.
How to use it
Enter the day you first saw heat signs. If she's bred and no heat appears around the next date, that's an early sign of pregnancy. Confirm it with your vet.
Reference chart
| Animal | Cycle length | Heat lasts |
|---|---|---|
| Goat | 21 days (18–24) | 12–36 hours |
| Cow | 21 days (18–24) | about 18 hours |
| Sheep | 17 days (14–19) | 24–36 hours |
| Pig | 21 days (18–24) | 2–3 days |
| Horse | 21 days (19–22) | 5–7 days |
Frequently asked questions
How often do goats come into heat?
About every 21 days during breeding season, with a normal range of 18 to 24 days. Many breeds cycle mainly in fall and winter.
How long is a cow's heat cycle?
About 21 days. Standing heat, when she stands still to be mounted, usually lasts around 18 hours.
What are the signs of heat?
Common signs include restlessness, tail flagging, a swollen or red vulva, calling, mounting others, and standing still to be mounted. Signs are strongest in goats and cows and easy to miss in sheep.
If she doesn't come back into heat, is she pregnant?
Often, yes. It's a good early sign, but not proof. A vet can confirm with ultrasound or a blood test.
Figures are typical values from university extension and breed-association guidance. Estimates only. Individual animals vary — confirm pregnancy and health questions with your veterinarian. Last reviewed 2026-09-18.