The most reliable way to tell if a male pig has been neutered is to check for the presence or absence of testicles in the scrotal area. A neutered male pig, called a barrow, will have a flat or slightly loose scrotal sac with no firm, oval-shaped masses inside. An intact boar will have two clearly palpable testicles. Beyond that quick check, several physical signs, scars, and behavioral clues can help you confirm what you’re dealing with.
Check the Scrotal Area First
In pigs, the testicles typically reach the scrotum between 10 days before birth and 14 days after. So by the time you’re looking at any pig older than a couple of weeks, both testicles should be fully descended and easy to feel in an intact male. They sit in a scrotal sac located beneath the tail, and in boars they’re notably large, with a prominent epididymis (the coiled structure attached to each testicle).
If you feel the scrotal area and find it empty, soft, and flat, the pig has likely been castrated. In younger or smaller pigs, you may need to gently palpate with your fingers to be sure nothing is there. The sac itself may still be present as a small flap of loose skin, but it won’t contain any firm structures.
One thing to watch for: a soft, reducible swelling in the scrotal or inguinal area doesn’t necessarily mean you’re feeling a testicle. Inguinal hernias, where intestinal tissue pushes into the scrotal region, can create a mass that mimics the look or feel of a testicle. The key difference is that a hernia feels soft and squishy and can often be pushed back up into the abdomen, while a testicle is firm, oval, and fixed in place.
Look for Castration Scars
If you’re examining a pig that’s already been neutered, there’s usually a visible scar. Where that scar appears depends on the surgical technique that was used.
- Scrotal castration: The most common method in farm pigs. The surgeon makes one incision over each testicle on the underside of the scrotum. These scars sit at the bottom of the scrotal sac, positioned low to allow drainage. In pigs castrated young, these scars can fade significantly and may be hard to spot without close inspection, especially if the pig has thick skin or hair.
- Pre-scrotal castration: Used in some cases, particularly with potbellied pigs. A single midline incision is made just in front of the scrotum, and both testicles are removed through it. This leaves one scar on the belly side of the groin rather than two on the scrotum itself. The incision is closed with sutures, so the scar tends to be a thin, linear line.
To find these scars, you’ll need the pig in a position where you can see the area between the hind legs. Having someone hold the pig or waiting until it’s relaxed and lying on its side makes the inspection much easier. Part the hair or bristles in the scrotal and pre-scrotal area and look for thin lines of scar tissue or areas where the skin texture differs from the surrounding tissue.
Behavioral Clues That Suggest an Intact Boar
If you can’t get a clear physical look, behavior can tell you a lot. Intact boars behave noticeably differently from neutered males. Research comparing intact males to females found that boars display significantly more aggression and mounting behavior. In one study, intact males mounted at a rate roughly 80 times higher than the comparison group. They’re also more active overall, pacing and moving around their enclosure more than castrated or female pigs.
Specific behaviors to watch for in an intact boar include:
- Frequent mounting of other pigs regardless of sex
- Increased aggression, including jaw chomping, shoulder pushing, and fighting
- Foaming at the mouth, which happens when boars produce frothy saliva containing pheromones
- Restlessness and pacing, especially around female pigs
A barrow, by contrast, tends to be calmer, less interested in mounting, and generally easier to manage. Castration removes the hormonal drive behind these behaviors. If your pig is placid, rarely mounts, and doesn’t show jaw-chomping or excessive salivation around other pigs, that’s a good behavioral sign he’s been neutered.
The Smell Test
Intact boars produce a distinct, strong musky odor that neutered males lack. This comes from compounds, primarily androstenone, that accumulate in the fat tissue of uncastrated males. The smell is often described as a sharp, urine-like musk that intensifies as the pig matures. It’s most noticeable when the pig is warm or when you’re near its head and neck area, where scent glands are concentrated.
Not everyone can detect androstenone equally. Some people are highly sensitive to it while others barely notice it. But if you’re standing near a mature male pig and notice a pungent, unpleasant odor that goes beyond normal pig smell, that pig is very likely intact. Barrows don’t produce this scent in any meaningful amount.
The Cryptorchid Complication
Here’s where things get tricky. A cryptorchid pig has one or both testicles that never descended into the scrotum. They remain trapped in the abdomen or the inguinal canal. This means you can examine the scrotal area, find it completely empty, and still be dealing with an intact male that produces testosterone and behaves like a boar.
If the pig has no visible scrotal scars, has an empty scrotum, but still displays classic boar behavior (mounting, aggression, strong musk), cryptorchidism is the most likely explanation. Veterinarians diagnosing this condition palpate the inguinal regions to check for a retained testicle near the groin. If the testicle is fully retained in the abdomen, it can’t be felt from the outside at all and requires ultrasound to locate. The retained testicle shows up on imaging as a structure with a characteristic texture that’s distinct from surrounding tissue.
In cases of one-sided cryptorchidism, you might find a castration scar on one side of the scrotum where the descended testicle was removed, while the other side shows no scar because the second testicle was never accessible from the scrotum. This combination of one scar plus boar-like behavior is a strong indicator that a retained testicle is still present and producing hormones.
Putting It All Together
The most definitive check is physical: feel for testicles and look for scars. If the scrotal sac is empty and you can find one or two castration scars, the pig is neutered. If the sac contains two firm, oval masses and there are no scars, he’s intact. Layer behavioral observations and scent on top of the physical exam for added confidence. A calm pig with no testicles, no musk, and visible scars is a barrow. A pig with an empty scrotum but boar-like behavior and strong odor warrants a veterinary exam for cryptorchidism, since a hidden testicle means the pig is functionally still intact.