Encephalitis and Encephalomyelitis in Pigs: Brain and Spinal Cord Disease

See your vet immediately if your pig is having seizures, cannot rise, seems mentally dull, or suddenly loses coordination.

Encephalitis is inflammation of the brain. Encephalomyelitis means the inflammation involves both the brain and spinal cord. In pigs, these problems are not one single disease. They are a syndrome of neurologic illness that can be caused by several infections and a few noninfectious conditions. One important infectious cause is teschovirus encephalomyelitis (also called Teschen or Talfan disease), a sporadic swine disease caused by Teschovirus A. Another recognized cause in very young piglets is porcine hemagglutinating encephalomyelitis, a coronavirus-associated disease that is most often seen in pigs under 4 weeks old that did not receive enough protective antibodies from nursing.

Because the brain and spinal cord control movement, balance, behavior, swallowing, and awareness, affected pigs may show a wide range of signs. Some pigs look weak or wobbly at first. Others progress to paddling, paralysis, or coma. The exact signs depend on which part of the nervous system is inflamed and how severe the damage is.

This is always a veterinary problem, not a wait-and-see problem. Neurologic disease in pigs can spread within a group, can resemble reportable or high-concern diseases, and can also be confused with conditions like Streptococcus suis meningitis, edema disease, or salt toxicosis. Your vet may need to evaluate both the individual pig and the herd situation.

Several different diseases can inflame the brain or spinal cord in pigs. A key infectious cause is teschovirus encephalomyelitis, which is caused by Teschovirus A. Merck notes that severe outbreaks are usually linked to highly pathogenic strains, while milder outbreaks are more often associated with other genotypes. Another recognized viral cause is porcine hemagglutinating encephalomyelitis virus (PHEV), a neurotropic coronavirus that mainly affects piglets younger than 4 weeks that did not receive enough lactogenic immunity from the sow.

Bacterial disease can also look very similar. Streptococcus suis is an important cause of meningitis in pigs and can produce listlessness, incoordination, dog-sitting posture, inability to stand, paddling, opisthotonos, and convulsions. In practice, your vet may also consider edema disease in recently weaned pigs, pseudorabies in certain epidemiologic situations, and toxic or metabolic problems that mimic encephalitis.

Not every pig with neurologic signs has true encephalitis. For example, salt toxicosis or water deprivation can cause blindness, circling, seizures, and coma. Edema disease can cause ataxia, paralysis, and recumbency in healthy-looking recently weaned pigs. That is why a careful history matters so much. Feed changes, water access problems, age group affected, recent movement, vaccination status, and whether one pig or many pigs are sick all help narrow the list.

Your vet may talk about a differential diagnosis list rather than naming one cause on day one. That is normal. In pigs, neurologic disease often requires herd context, lab testing, and sometimes postmortem tissue evaluation before the cause is confirmed.

Diagnosis starts with an urgent physical and neurologic exam by your vet. They will ask about the pig’s age, onset of signs, water intake, feed changes, recent stress, vaccination history, and whether other pigs are affected. That history helps separate likely infectious causes from toxic or management-related problems.

Testing often includes a combination of bloodwork, herd history, and targeted infectious disease testing. Depending on the case, your vet may recommend PCR testing on swabs or tissues, bacterial culture, and other lab work to rule in or rule out conditions such as teschovirus, bacterial meningitis, or other neurologic diseases. In many swine cases, especially when a pig dies or is euthanized, necropsy with histopathology and tissue PCR gives the clearest answer because lesions in the brain and spinal cord can help distinguish one disease from another.

This is one of those conditions where diagnosis may focus on both the sick pig and the group. If several pigs are affected, your vet may advise isolation, movement restrictions, and submission of tissues through a veterinary diagnostic laboratory. That approach can protect the rest of the herd and may be important if a foreign animal disease or reportable disease is part of the rule-out list.

Typical 2025-2026 US cost ranges vary by region and whether care happens on-farm or through a hospital. A farm-call exam and basic supportive visit may run about $250-$600. Adding bloodwork and sample collection often brings the total to $400-$900. Necropsy and lab testing may add $150-$700+, while intensive hospitalization, repeated visits, or advanced imaging can push costs into the $1,500-$3,000+ range.

Prevention depends on the cause, but the big themes are biosecurity, immunity, sanitation, and early veterinary involvement. For infectious neurologic disease, isolate new arrivals, limit unnecessary pig movement, clean and disinfect housing, and avoid mixing age groups when possible. Good colostrum intake matters, especially for young piglets. Merck notes that outbreaks of porcine hemagglutinating encephalomyelitis are rare partly because nursing sows pass protective antibodies to piglets.

Daily management also matters. Make sure pigs have reliable access to clean water at all times, because water deprivation can trigger severe neurologic disease that mimics encephalitis. Review feed storage and feed changes carefully, reduce overcrowding and stress where possible, and work with your vet on vaccination and herd-health planning that fits your setup.

If one pig develops neurologic signs, act fast. Separate the pig, minimize stress, and call your vet right away. Early action may not only help that pig, but also reduce spread, identify management problems, and protect the rest of the group.

There is no single prevention plan that fits every pig household or farm. Your vet can help you build a practical prevention strategy based on age groups, housing, exposure risk, and whether you keep one pet pig or a larger group.