During a walk-through of a pig farm, if you see a pig eating less, passing hard, pellet-like feces, and showing abnormal behavior such as restlessly standing and repeatedly circling the perimeter of its pen, many farmers’ first reaction is often: “The pig has too much internal heat and is constipated. Just feed it some greens and give it an enema.”
With simple constipation alone, a pig usually just strains to defecate while remaining relatively alert. But once “restlessness and circling the pen” are also present, the nature of the problem changes—this usually means the pig’s intestines are experiencing severe pain or have developed a serious mechanical obstruction, which is a typical sign of an “acute abdomen.” Treating it blindly with strong medication as ordinary constipation can easily lead to intestinal rupture or delay treatment.
So, what exactly causes this combination of symptoms: “dry feces + reduced feed intake + circling due to abdominal pain”?
Why is the pig “restless on its feet and pacing in circles around the pen”?
Before analyzing the causes, first understand the pathological basis of this behavior. Pigs are very stoic animals. When a pig cannot lie down comfortably and can only relieve abdominal discomfort by walking and circling constantly, it indicates that the pig is experiencing persistent or intermittent severe abdominal pain (colic). Hard, dry feces accumulating in the intestines, gas produced by abnormal fermentation, or physical twisting of the intestines can all severely stimulate the intestinal nerves, causing the pig to become restless.
Considering the “dry, pellet-like feces” and “eating less feed,” the main causes of this series of symptoms fall into the following two categories:
Category One: Organic Lesions (Most Dangerous, Can Be Fatal)
Constipation caused by these factors often does not respond to medication, and delays can lead to rapid death in pigs.
1. Mechanical intestinal obstruction (intestinal impaction, intussusception, intestinal torsion)
This is the most dangerous cause of “circling around the pen.” Long-term feeding of a single, overly fine-textured feed, a lack of crude fiber, sudden strenuous activity by the pig (such as fighting or running wildly when startled), or irritation from parasites in the intestines can easily cause a section of intestine to become intussuscepted or twisted. Hard, dry fecal pellets block the intestine like a plug. The intestine spasms violently in an attempt to empty itself, causing severe pain. The pig is unable to stand still because of the pain and repeatedly strains to defecate but cannot pass stool. As the intestine becomes necrotic, the condition can quickly progress to abdominal swelling, vomiting, and even death.
2. Severe colonic/rectal constipation (intractable fecal impaction)
Most commonly seen in pregnant sows or older pigs in poor physical condition. Prolonged lack of exercise and insufficient water intake cause the feces in the latter part of the colon to dry out completely, forming clusters of fecal pellets as hard as stones. These large fecal masses press against the intestinal wall, causing severe pain and obstructing blood circulation, which can lead to local intestinal necrosis.
Category two: Functional disorders and toxin irritation (a wide range of contributing factors)
In the early stages, these causes often present as simple constipation and reduced feed intake. However, if ongoing toxin accumulation triggers systemic inflammation or fever, it can also cause abdominal pain and restlessness.
1. Severe water intake deficiency (the first hidden killer)
Water is key to lubricating the intestines. If the water pressure at the drinkers on a pig farm is insufficient, the water flow is too low, or the water is too cold (in winter) or has an unpleasant odor, pigs may be unwilling to drink or may not drink enough. The intestines then absorb water from the feces excessively, causing the feces to be expelled in pellet-like form. Combined with reduced feed intake, intestinal peristalsis slows further, creating a vicious cycle.
2. Improper feed and nutritional ratios
Insufficient crude fiber: Modern pig farms use large amounts of high-concentrate feed (corn and soybean meal) and lack crude fiber sources such as bran. Insufficient crude fiber intake deprives the intestines of “bulk stimulation,” greatly weakening peristalsis.
Feed ground too finely: Finely ground feed can easily form a paste in the intestines, which then dries and hardens.
Mycotoxin levels exceeding the limit: Long-term consumption of feed containing mycotoxins (especially vomitoxin and T-2 toxin) can cause inflammation and ulcers in the gastrointestinal mucosa. Stomach pain causes pigs to eat less, and intestinal function subsequently becomes paralyzed.
3. Environmental and stress factors
In autumn and winter, temperatures can drop sharply. If the pig housing is not adequately insulated, pigs’ abdomens may become chilled, causing the smooth muscles of the gastrointestinal tract to spasm in response to the cold. This disrupts the rhythm of peristalsis and leads to constipation. In addition, high-density confinement (such as keeping sows in gestation stalls for a long time) leaves them with almost no exercise, severely reducing gastrointestinal motility.
4. Secondary infectious diseases (such as classical swine fever and eperythrozoonosis)
In the early stages of some mild forms of classical swine fever and porcine epidemic diarrhea, or in blood protozoan diseases (Eperythrozoonosis), fever in pigs (often presenting as a sustained fever) can severely impair normal intestinal function. Affected pigs may first develop hard, dry constipation, which often turns into diarrhea later, accompanied by extreme lethargy and red patches or pinpoint hemorrhages on the skin.
Emergency on-site response plan: Assess first, then intervene
When you encounter a pig in this condition, do not immediately administer large doses of potent laxatives such as magnesium sulfate or rhubarb. If the intestine is already obstructed or even twisted, a strong laxative could cause the intestinal tract to rupture.
Step one: Palpation assessment (diagnosis)
Gently feel the pig’s abdomen by hand, especially the flank. If you feel a string of hard, abacus-bead-like lumps and the pig does not resist violently, it is most likely severe constipation. If the pig resists intensely and squeals loudly during palpation, or if one area of the abdomen feels stretched tight like a balloon and sounds hollow when tapped, intestinal torsion or intussusception is strongly suspected. Medication will not work in this situation; contact a veterinarian as soon as possible for exploratory surgery or cull the pig to limit losses.
Step two: Gentle laxation (for uncomplicated severe constipation)
Administer a lubricant orally: Give 200-500 milliliters of liquid paraffin (or edible vegetable oil). Paraffin is not absorbed by the intestines and can effectively lubricate the entire intestinal wall.
Soften the feces: Use a deep enema of warm soapy water (or 0.1% potassium permanganate solution) to soften the dry, hard fecal balls at the end of the rectum.
Fluid replenishment: Administer glucose saline by intraperitoneal injection or intravenous drip to correct dehydration and relieve abdominal pain in pigs.
Step three: Relieve spasms and pain
If a pig circles frequently and is extremely restless, this indicates that its abdominal pain is unbearable. An antispasmodic and analgesic (such as atropine or a specific analgesic) may be used to relieve excessive spasms of the intestinal smooth muscles and calm the pig, under veterinary guidance.
Step four: Repair and adjustment
After the feces have been passed, feed the pigs probiotics and wet-mixed feed for several consecutive days, and add electrolytes and multivitamins to their drinking water to help restore the gut microbiota. For sows kept in stalls, try to provide some green forage during postpartum recovery.
Summary
“Constipation, reduced feed intake, and abdominal pain with circling” are not minor problems when they occur together. They remind us that, while pursuing rapid growth and a favorable feed-to-meat ratio, we must not overlook the need to provide pigs with sufficient drinking water, a moderate amount of dietary fiber, and enough space to move around. Only when the gut is functioning properly can pigs remain comfortable; once the gut is obstructed, even the best feed and medicines cannot work. (Source: Zhang Weiguang)