If you’ve ever stood at the edge of a pig pen at dawn, mug of coffee in hand, trying to figure out if your sow is ready to breed, you’re not alone. On my small farm the first time I tried to track the heat cycle in pigs it felt like guesswork. I’d heard all sorts of tips from old hands at the feed store, but nobody handed me a neat checklist. I learned the hard way, missing a cycle and then waiting three more weeks for the next chance. That wait taught me patience but it also taught me to watch my animals closely.

Heat detection in pigs is not some distant science reserved for large commercial barns. Even in a backyard setup or a smallholder farm, you can train your eye to pick up the signs. It’s about noticing changes in behavior, appetite, and body posture. Once you get used to it, you’ll find yourself predicting a sow’s readiness almost down to the day. There’s real satisfaction in that. You can plan breeding better, save time and feed, and raise stronger litters.

I want to share what actually works for me and other small farmers I know. This isn’t a corporate manual; it’s the kind of list you’d get if we were sitting at a kitchen table with a notebook between us. We’ll go over ten easy ways to spot the heat cycle in pigs, slip in a real-life story or two, and cover some practical tips. By the end, you’ll feel confident about reading your pigs rather than guessing. Ready?

10 Easy Ways to Know the Heat Cycle in Pigs

Here are 10 Easy Ways to Know the Heat Cycle in Pigs;

1. Watch for Restlessness

One of the first signs I see when a sow is coming into heat is restlessness. She’s up and moving when she’d normally be lying down, nosing around the pen more than usual. It’s a subtle change at first but grows stronger. Ask yourself: “Why is she pacing today?” That simple question can save you missing the window.

2. Changes in Appetite

Sometimes a sow in heat will eat less of her usual ration, or she’ll pick at it instead of gobbling it up. Other times she’ll seem hungrier but more distracted. Either way, a noticeable change in appetite during the expected time frame can point you toward the heat cycle in pigs. Keep a small notebook of feed intake if you’re unsure; patterns pop out over a few weeks.

3. Swelling and Reddening of the Vulva

This is one of the most reliable physical signs. In gilts and younger sows the swelling and redness can be dramatic. In older sows it’s subtler but still visible if you look. Check daily around the expected period so you don’t miss the change. A little flashlight on an early morning check can be a farmer’s best friend.

4. Standing Reflex Test

This is a classic. Place gentle pressure on the sow’s back near the loin area. A sow in heat will “lock up” or stand still with ears pricked, accepting the pressure. This reflex means she’s ready for the boar. It’s simple but powerful. On my farm we call it “the back test” and even my teenage son can do it.

5. Increased Vocalization

A sow in heat tends to grunt, squeal or call more often. The sound is higher and more persistent than usual. She may also respond to boar noises from a distance. If you’ve ever heard your pigs suddenly talking more, stop and watch—heat may be starting.

6. Mounting or Standing for Other Pigs

Sometimes you’ll see your gilt trying to mount pen mates, or standing firm while others nudge or climb on her. This behavior is a giveaway. It can look rough to newcomers, but it’s just pigs showing hormonal changes. This is one of the reasons it’s easier to detect the heat cycle in pigs when they’re housed in groups rather than alone.

7. Seeking Out the Boar

If you have a boar nearby, a sow in heat will head for his side of the fence, linger at the divider, and show more interest in him than usual. Even his scent or sound can trigger a stronger response. This is especially helpful if you don’t have time to stand and watch all day; a quick look at where she’s hanging out tells you plenty.

8. Change in Tail and Ear Posture

It might sound minor, but experienced farmers notice tails held differently—stiffer or curled tighter—and ears pointing forward more often. These subtle posture changes can clue you in before the more obvious signs show. It’s a quiet trick that only comes from watching pigs closely.

9. Milk Line Disappearance in Lactating Sows

If you’re breeding back a sow after farrowing, you’ll notice her milk line changing. As weaning approaches and she cycles again, the udder will shrink a bit and the milk line may fade. Combine that observation with the other signs here and you’ve got a solid indicator.

10. Tracking with a Calendar

All of these signs become clearer if you know when to look. Gilts generally cycle every 18–24 days. Mark dates on a wall calendar in the barn or use an app if that’s your thing. When you know the window, you’ll catch the subtle behaviors faster. This is the simplest but most powerful “way” of all.

Real Life Scenario

I once had a gilt named Rosie. She was gentle but shy and never gave big obvious signals. The first time I tried to breed her I missed her cycle completely. The second time, armed with my checklist, I caught the slight change in her appetite and the way she stood by the boar pen. We bred her that day and got a healthy litter of eleven piglets. The difference was just paying attention to the little things.

How-To: Running the Back Pressure Test

• Approach your sow calmly.

• Place one hand on her back near the shoulders and apply gentle pressure.

• A sow in standing heat will brace her legs and remain still.

• If she walks away or sidesteps, she’s not quite there yet.

How-To: Keeping Simple Records

• Note the date of last observed heat.

• Jot down changes in behavior or appetite.

• Record breeding dates and expected farrowing dates.

• Over time your notes will be more accurate than guesswork.

FAQs on Heat Cycle in Pigs

How often do pigs come into heat?

Most sows and gilts show heat every 18–24 days until bred.

How long does the heat period last?

Typically 2–3 days, with the best breeding time about 12–24 hours after standing heat begins.

Can I breed my gilt on her first heat?

It’s often better to wait until her second or third cycle for a stronger litter, but she can conceive on her first.

What if I miss the heat cycle in pigs?

You’ll have to wait for the next cycle. Keeping records helps you avoid missing it again.

Do boars help detect heat?

Yes. Even just having a boar nearby can stimulate and reveal heat in sows and gilts.

Putting It All Together

Learning to read the heat cycle in pigs isn’t about memorizing one dramatic sign; it’s about seeing the pattern of several small changes. When you start combining restlessness, appetite changes, swelling, and the standing reflex with a calendar, you’ll rarely miss the window again. Each farm is different, each pig has its quirks, but the principles hold true everywhere.

So take your time, watch your pigs, keep simple notes, and trust your instincts. The more you work with them, the better your eye becomes. Before long you’ll know without thinking when your sow is ready. Which of these ten signs have you already noticed in your own pigs?