On a pig farm, the most regrettable problems are often not incurable diseases, but rather those situations where “something seemed a little off long ago, but it wasn’t taken seriously.” Pigs are extremely good at hiding illness (in nature, showing weakness means being eliminated). By the time they display clear symptoms, the disease is often already at the middle or late stage.
But no matter how well they are concealed, physiological changes in the body will give them away. True experts at raising pigs never wait until a pig lies down and stops eating before treating it. Instead, they observe how the pig walks, sleeps, and defecates, and what color its skin is.
Based on the daily inspection routine at pig farms, we can group early signs of disease into five categories. By keeping a close eye on these changes, most serious diseases can be intercepted in advance.
I. Spotting abnormalities through “feed intake and water consumption” (the most obvious warning sign)
A pig’s appetite is a barometer of its health. If feed intake across the entire herd suddenly drops, or a pig roots around for food just twice and then walks away, something is definitely wrong.
A dramatic increase in water consumption: Pigs suddenly drink excessively, even drinking dirty water from the manure channel. This is often a precursor to a febrile disease (the elevated body temperature causes substantial water loss), or to kidney strain caused by salt poisoning or mycotoxins (vomitoxin). If the dramatic increase in water consumption is accompanied by severe vomiting and neurological symptoms, salt poisoning must be strongly suspected.
A sharp drop in water consumption: If pigs are reluctant to drink, in addition to checking whether the drinker is blocked, be alert to foot-and-mouth disease (blisters in the mouth that are so painful the pigs are afraid to open their mouths), swine fever, or a severe systemic infection.
“Eat, vomit, eat again”: What pigs vomit is an acidic, foul-smelling mash or feed that has not been digested, and they eat again after vomiting. This strongly suggests gastric ulcers. If the vomit contains streaks of blood or looks like coffee grounds, this indicates that gastric bleeding has occurred.
Two. Assessing the lesion through the “skin surface” (the clue most easily overlooked)
A pig’s skin color and integrity directly reflect the state of its blood circulation and immune system.
Pale skin: Under normal conditions, a pig’s skin is pink. If the pig’s ears, conjunctiva, or abdominal skin are very pale, this indicates severe anemia. Common causes include eperythrozoonosis (often accompanied by yellowish urine), chronic bleeding from gastric ulcers, or severe parasitic infections (such as roundworms or whipworms).
Skin redness/purplish discoloration: If purplish-red patches appear on the ears, underside of the abdomen, or extremities and do not blanch when pressed, sound the ASF alarm immediately. In addition, porcine reproductive and respiratory syndrome (PRRS), classical swine fever, and septicemic streptococcal infection can also cause similar symptoms.
Square/diamond-shaped red rashes: If raised, stamp-like diamond-shaped or square red rashes appear on a pig’s back or abdomen, this is a typical symptom of swine erysipelas (commonly known as “fire marks”).
Bleeding from the pores / rust-colored spots: Carefully examine the pores on the back. If there are pinpoint-sized bleeding spots or rust-colored spots, Eperythrozoonosis is strongly suspected.
Tear staining and conjunctival redness and swelling: A large amount of dark brown tear staining is present at the corners of the eyes, and the conjunctiva is red. This suggests that the ammonia concentration in the pig barn exceeds the limit, or that atrophic rhinitis or liver and kidney damage caused by mycotoxin accumulation is present.
Three. Hidden conditions seen through “breathing and posture” (respiratory and neurological symptoms)
Abnormal sleeping positions and huddling: Healthy pigs lie on their sides with their bodies stretched out. If piglets huddle in piles, this indicates that the temperature in the pig house is too low or there is a draft. If a pig sits in a “dog-sitting position” (front legs supporting the body, hindquarters on the ground, neck stretched out while panting), this indicates severe respiratory distress, commonly seen in contagious pleuropneumonia, swine pasteurellosis, or acute PRRS.
Abdominal breathing (panting): Healthy pigs breathe steadily. If you see a pig’s belly rapidly rising and falling with each breath, it means the pig is using its abdominal muscles to help it breathe. This is an early sign of mycoplasmal pneumonia, porcine pleuropneumonia, or PRRS.
Aimless circling and paddling: The pig walks aimlessly, presses its head against walls, falls down, and paddles its limbs as if swimming, with foam at the mouth. This is typical of central nervous system damage. First, rule out pseudorabies (especially in suckling piglets), the encephalitic form of streptococcosis, or edema disease (common 1-2 weeks after weaning, often accompanied by swollen eyelids).
Four. Looking at the digestive system through “excrement” (the most genuine internal feedback)
The feces are dry, hard, and pellet-shaped: the pig passes dry, hard pellets resembling sheep droppings, which may be covered with mucus. This indicates slowed intestinal motility or dehydration. It is commonly seen in the early stages of febrile diseases (classical swine fever, African swine fever), in sows with postpartum anorexia, or after prolonged confinement housing.
Blood in stool / black stool:
If bright red blood is on the surface of the feces, the bleeding is most likely from the lower digestive tract, such as swine dysentery (a spirochete infection, often accompanied by jelly-like mucus) or proliferative ileitis (acute hemorrhagic form).
If the stool is black and tarry, this indicates upper gastrointestinal (stomach) bleeding and suggests a severe stomach ulcer.
Watery diarrhea (projectile): If piglets suddenly develop severe watery diarrhea accompanied by vomiting and rapid dehydration (the skin is slow to return to normal after being pinched), be highly alert to porcine epidemic diarrhea (PED) or transmissible gastroenteritis (TGE).
Urine discoloration: Healthy pigs have colorless or slightly yellow urine. Dark tea-colored or soy sauce-colored urine is a strong sign of eperythrozoonosis; if there is blood in the urine, check for urinary stones and cystitis.
V. Hidden Risks in Sows from a “Reproductive System” Perspective (Directly Affecting Production Capacity)
Abnormal lochia: After giving birth, a sow discharges grayish-white or yellowish-brown purulent secretions, or secretions with a foul odor, indicating endometritis.
Vulvar swelling and discharge: The vulva of a sow swells outside of estrus and discharges white, chalky or yellow, purulent mucus. This is often seen in cases of mycotoxin poisoning (especially when zearalenone F-2 toxin levels exceed the limit) or Japanese encephalitis infection.
Mammary abnormalities: A sow refusing to nurse after farrowing, with swollen, red, hard, hot mammary glands and no milk, is showing typical signs of mastitis-metritis-agalactia syndrome (MMA). If detected early, prompt warm compresses and anti-inflammatory treatment can help save the litter.
Appendix: The “look, listen, ask, and feel” techniques for efficient patrols
Truly spotting a problem at a glance depends on establishing standardized patrol habits.
1. Quiet: Do not turn on the lights or make loud noises immediately upon entering the pigsty. Stand quietly at the entrance and observe for two minutes. Check whether any pigs are isolated from the group, whether any pigs are coughing, and whether any pigs are vomiting in the corners.
2. Smell: Take a deep breath. Is there a pungent ammonia odor? Is there a noticeable fishy smell (suggesting diarrhea has occurred)?
3. Move: urge the pig to move. A healthy pig will quickly get up and move away. If it does not move when urged, or gets up but then hunches its back or limps, it is definitely uncomfortable.
4. Check: Carefully observe the shape of the feces on the ground. Is there any diarrhea? Are there any dry fecal pellets? Is there any blood in the feces?
In closing:
There is a wise saying in pig farm management: “If a pig suddenly dies today, it must already have been sick yesterday.”
The onset and progression of disease follow a process. If, during our daily rounds, we take an extra look at the pigs’ skin and the feces on the ground, and listen for an extra cough from the pigs, we can spot these “distress signals” early, isolate the animals promptly, make an early diagnosis, and intervene early. Many devastating disease outbreaks can then be contained in their early stages. (Source: 张伟光)