Sudden Pig Death: 8 Differential Diagnoses Every Farmer Must Know

The worst message a pig farmer can wake up to is from their worker: "A pig died overnight." No symptoms observed, no warning signs, just a dead animal in the pen. The first question is always "Why?" — and the answer matters enormously, because if it is ASF (African Swine Fever), the entire herd is at risk within days. If it is edema disease, the rest of the litter can be treated and saved. If it is heat stress, you need to fix ventilation immediately.

This article walks through the 8 most common causes of sudden pig death in African pig farms, ranked by frequency. For each, you will learn: how to identify it, what to do immediately, and how to protect the rest of your herd [1][2].

The 8 causes of sudden pig death

1. African Swine Fever (ASF) — the most feared

How to identify: ASF is a viral hemorrhagic disease with mortality rates of 90-100% in acute form [3]. The pig typically shows: high fever (41-42°C), loss of appetite, redness/blueness of the skin (especially ears, abdomen, legs), difficulty breathing, vomiting, sometimes bloody diarrhea. Death occurs within 7-10 days of first symptoms. In peracute form, the pig may die within 24-48 hours with few visible signs.

The critical diagnostic clue: Multiple pigs in the same pen get sick simultaneously or in rapid succession. ASF does not kill just one pig and leave the rest healthy — if one dies suddenly and 2-3 others have fever, suspect ASF immediately.

What to do: There is NO treatment and NO vaccine for ASF. If you suspect ASF: (a) do NOT move any pigs, feed, or equipment off the farm; (b) isolate the sick pigs; (c) call the national veterinary service immediately — ASF is a notifiable disease in most African countries; (d) do NOT slaughter or sell any pigs; (e) disinfect the entire farm with strong alkali (2% sodium hydroxide) — ordinary disinfectants may not kill the ASF virus; (f) rest the farm for 90 days minimum after the last death.

Protect the rest of the herd: Unfortunately, if ASF is confirmed, culling the affected pen AND all contact pigs is the only way to save the rest. Notify neighboring farmers within 5km — they need to take immediate biosecurity measures.

2. Edema Disease — the most misdiagnosed

How to identify: Edema disease is caused by Shiga-toxin producing E. coli bacteria, typically affecting weaned piglets 1-2 weeks after weaning [4]. The hallmark symptom is SWOLLEN EYELIDS — the pig looks like it has bags under its eyes. Other symptoms: sudden death, incoordination (staggering, wobbling), head tilt, difficulty breathing, subcutaneous edema (swelling under the skin of the forehead and eyelids).

Why it is misdiagnosed: The sudden death + staggering often gets confused with ASF or classical swine fever. But ASF does NOT cause swollen eyelids. If you see swollen eyelids, it is edema disease, NOT ASF. This distinction is critical — edema disease is treatable, ASF is not.

What to do: Treatment is possible if caught early: (a) Atropine 0.04-0.08 mg/kg subcutaneously (reduces secretions); (b) Sulphadimidine (sulfamethazine) 50-100mg/kg IM or oral (antibiotic against E. coli); (c) Procaine penicillin IM; (d) Corticosteroids (dexamethasone) to reduce edema; (e) Electrolytes with glucose orally to prevent dehydration. Treat ALL pigs in the affected pen, not just the sick ones — the E. coli is spreading and others are incubating. Disinfect the pen thoroughly with strong disinfectant after treatment.

3. Classical Swine Fever (CSF / Hog Cholera)

How to identify: CSF is clinically indistinguishable from ASF in the field — both cause high fever, hemorrhages, and high mortality [5]. The only way to tell them apart is laboratory testing. CSF mortality is 80-100% in unvaccinated herds. Symptoms: fever (41-42°C), lethargy, loss of appetite, conjunctivitis, purple discoloration of skin, diarrhea, neurological signs in chronic form.

What to do: Unlike ASF, CSF HAS a vaccine (lapinised or cell-culture adapted, costs 300-500 FCFA per dose in Cameroon). If CSF is confirmed and you have other pigs not yet sick, emergency vaccination can save them. But you must act within 3-5 days of the outbreak. Call the vet immediately for diagnosis + vaccine. CSF is also a notifiable disease.

4. Streptococcus suis infection

How to identify: A Brazilian study found Streptococcus suis to be the most common cause of piglet death (21.2% of cases) [1]. It causes meningitis, septicemia, arthritis, and sudden death. Symptoms: fever, depression, reluctance to move, tremors, paddling, convulsions, loss of coordination. Most common in piglets 2-12 weeks old.

What to do: Treat with penicillin or amoxicillin IM for 5-7 days. Anti-inflammatories (flunixin, meloxicam) for meningitis. Affected pigs often respond within 24-48 hours if treated early. Prevent by improving hygiene, reducing stress (overcrowding, temperature fluctuations), and considering autogenous vaccine for herds with chronic problems.

5. Hemorrhagic Bowel Syndrome (HBS)

How to identify: HBS is characterized by sudden death with a pale, bloated carcass [2]. When you open the abdomen, the bowel is filled with blood. The pig typically seemed healthy hours before death. Most common in growing pigs (40-100kg) on high-energy feed. The cause is not fully understood but may involve Clostridium perfringens or feed-related factors.

What to do: There is no treatment because death is too sudden. Prevention: reduce feed density, add dietary fiber (wheat bran, oat hulls), ensure adequate water intake, avoid sudden feed changes, control coccidiosis. If multiple pigs die of HBS, review your feed formulation.

6. Heat stress

How to identify: Most common in hot humid weather (>32°C with >70% humidity). The pig is found dead in the morning, often in a corner of the pen where it tried to escape heat. Body is warm to the touch even hours after death. Pigs that died of heat stress often have open mouths (panting at death), purple skin, and rapid decomposition.

What to do: Prevention is the only treatment. Improve ventilation, provide shade, add electrolytes + vitamin C to drinking water during heat waves, feed during coolest hours (5-7 AM, 8-10 PM), reduce stocking density. See our dedicated article on heat stress management for the full protocol.

7. Internal trauma (pen aggression)

How to identify: The pig was attacked by pen-mates, separated, found dead next morning. There may be visible bite wounds, or the trauma may be internal (ruptured liver, spleen, or blood vessel). Dexamethasone injection immediately after the attack can reduce internal bleeding and save the pig — but only if given within 4-6 hours of the trauma.

What to do: If a pig is attacked, immediately: (a) separate it from the aggressors; (b) examine for wounds; (c) inject dexamethasone 5-10ml IM (anti-inflammatory, reduces internal bleeding); (d) inject vitamin K 2-5ml IM (promotes blood clotting); (e) if wounds are deep, give antibiotics (Penstrep) for 3-5 days; (f) keep the pig quiet and isolated for 24-48 hours. If the pig is still alive after 24 hours, it will likely survive.

Prevention: Pen aggression is caused by overcrowding, mixing unfamiliar pigs, hunger (competition for feed), or boredom. Provide adequate space (1m² per 100kg pig), do not mix unfamiliar pigs, ensure enough feeder space (1 feeder per 4-5 pigs), and provide enrichment (chains, tires to root at).

8. Poisoning

How to identify: Multiple pigs get sick or die simultaneously with similar symptoms. Common poisons: rat poison (warfarin — causes bleeding), moldy feed (aflatoxins — causes liver failure), toxic plants (cassava leaves with cyanide, oleander), chemical poisoning (pesticides, herbicides from contaminated water or spray drift).

What to do: Identify and remove the source immediately. For rat poison (warfarin), give vitamin K injection + oral vitamin K for 7-14 days. For moldy feed, stop feeding it immediately, give activated charcoal + electrolytes. For chemical poisoning, call a vet immediately — specific antidotes may exist.

The diagnostic decision tree

When you find a dead pig, work through these questions:

1. Was only ONE pig affected, or multiple? Multiple → suspect ASF, CSF, or poisoning. One → suspect trauma, heat stress, HBS, or individual disease.
2. Are there visible swollen eyelids on the dead (or sick) pigs? Yes → Edema disease (treatable). No → continue down the list.
3. Did the pig have a fever before death (ask the worker who last saw it)? Yes → infectious disease (ASF, CSF, Streptococcus, E. coli). No → trauma, heat stress, HBS, or poisoning.
4. Was the pig attacked by others? Yes → internal trauma. Dexamethasone + vitamin K for survivors.
5. Is the weather hot and humid? Yes → heat stress likely. Improve ventilation + electrolytes.
6. Is the feed moldy or new? Yes → aflatoxin poisoning possible. Stop the feed.
7. Are there external signs of bleeding from nose, mouth, anus, or skin? Yes → hemorrhagic disease (ASF, CSF, HBS, warfarin poisoning).
8. Are the piglets 2-12 weeks old? Yes → Streptococcus suis or edema disease most likely.

What to do immediately after finding a dead pig

1. Quarantine the pen. No animals, people, or equipment leave the pen. Disinfect your boots before leaving.
2. Examine the carcass. Look for: swollen eyelids, skin discoloration, bite wounds, bloating, bleeding from orifices, condition of the anus (scour staining?).
3. Take the body temperature. A live pig's temperature is 38.5-39.5°C. A recently dead pig retains heat for 2-4 hours. If the temperature is >40°C, the pig had a fever before death.
4. Take photos. Photograph the carcass from all angles, plus any visible lesions. Send to a vet or post in a farmer group with experienced members.
5. Bury or burn the carcass. Deep burial (2m) with quicklime, or burning. Do NOT leave the carcass for scavengers — they spread disease.
6. Disinfect the pen. Remove all bedding, wash with disinfectant (iodine or chlorine-based), let dry 24 hours before reintroducing pigs.
7. Monitor the rest of the herd. Check temperatures of all pigs in the same pen + adjacent pens twice daily for 7 days. Any pig with fever >40°C is a red flag.
8. Call the vet if: multiple pigs die within 48 hours, fever is present, or you suspect ASF/CSF. Early intervention saves the herd.

FarmWise tracks every mortality event with cause attribution, symptoms observed, and treatment given. Over time, patterns emerge — "I have lost 8 weaners in 3 months, all from Streptococcus" — and the dashboard recommends the right preventive protocol. When multiple farmers in the same region log similar symptoms, the outbreak alert system notifies everyone nearby.

Sources & References

• [1] PMC (PubMed Central): Main Causes of Death in Piglets from Different Brazilian Regions — Streptococcus suis infection was the most prevalent cause of death (21.2%), followed by bacterial polyserositis (16.7%). Source: pmc.ncbi.nlm.nih.gov
• [2] National Hog Farmer: Common Causes of Sudden Death in Finishing Pigs — sudden death can be divided into enteric conditions, respiratory infections, and individual pig events. Source: nationalhogfarmer.com
• [3] WOAH (World Organisation for Animal Health): African swine fever — mortality rates approach 100% in acute form. Source: woah.org
• [4] Merck Veterinary Manual: Edema Disease in Pigs — peracute vasculitis causing facial swelling in post-weaning pigs, caused by Shiga toxin-producing E. coli. Source: merckvetmanual.com
• [5] PMC: African and classical swine fever: similarities, differences and diagnostic approaches — ASF and CSF are clinically indistinguishable in the field. Source: pmc.ncbi.nlm.nih.gov