Meningitis and Myelitis in Sheep: Neck Pain, Fever, Weakness, and Seizures

Meningitis means inflammation of the membranes around the brain and spinal cord. Myelitis means inflammation of the spinal cord itself. In sheep, these problems often overlap with encephalitis, which is inflammation within the brain. Together, they can cause a fast-moving neurologic illness with fever, pain, weakness, behavior changes, and trouble standing or walking.

This is not one single disease. It is a syndrome with several possible causes, including bacterial infection, less commonly viral disease, septicemia in young lambs, and spread of infection from nearby tissues or the bloodstream. In adult sheep, listeriosis is one of the most important infectious causes of meningoencephalitis, especially when flock history includes poor-quality silage or baleage.

Because the brain and spinal cord control movement, balance, swallowing, vision, and awareness, affected sheep can decline quickly. A sheep may start off dull and off feed, then develop neck pain, circling, facial asymmetry, recumbency, or seizures. Prompt veterinary care gives your flock the best chance of identifying the cause and deciding which treatment path fits the situation.

The most important infectious cause to rule out in many adult sheep is listeriosis, caused by Listeria monocytogenes. Merck notes that the common neurologic form in ruminants is a localized ascending infection of the brainstem, and Cornell has documented sheep with bacterial meningitis and cervical spinal cord inflammation caused by Listeria. Poorly fermented silage or baleage is a classic risk factor, although not every case has a clear feed trigger.

Young lambs can also develop meningitis as part of septicemia, where bacteria spread through the bloodstream from the navel, gut, lungs, or other infected tissues. In any age group, infection may occasionally spread from abscesses, wounds, ear or sinus disease, or severe systemic illness. Less common differentials include viral encephalomyelitis in regions where those diseases occur, toxic or metabolic disorders that mimic CNS inflammation, rabies, scrapie, brain abscesses, and other neurologic diseases.

Risk often rises when flock management is under strain. Poor silage quality, overcrowding, abrupt weather stress, inadequate colostrum in lambs, poor sanitation, and delayed isolation of sick animals can all increase the chance that a neurologic case becomes severe or that more than one sheep is affected. Your vet will use age, feed history, season, flock pattern, and the exact neurologic signs to narrow the list.

Diagnosis starts with an urgent farm exam. Your vet will check temperature, hydration, mentation, gait, cranial nerve function, neck pain, and whether the signs point more toward brain, brainstem, or spinal cord disease. Merck notes that neurologic examination and cerebrospinal fluid, or CSF, analysis are important starting points when evaluating meningoencephalitic disease in animals.

Depending on the sheep's condition and what is practical on-farm, testing may include bloodwork, fecal review if other disease is possible, and CSF collection for cell counts and protein. In suspected listeriosis, diagnosis is often based on the pattern of neurologic signs and flock history, because treatment cannot wait for perfect confirmation. If a sheep dies or is euthanized, necropsy with histopathology, bacterial culture, PCR, and rabies testing may be the fastest way to protect the rest of the flock and clarify whether feed, environment, or biosecurity changes are needed.

Your vet may also work through look-alike conditions such as polioencephalomalacia, pregnancy toxemia, lead toxicity, brain abscess, scrapie, and rabies. That step matters because the treatment plan, prognosis, and flock implications can be very different even when the first signs look similar.

Prevention starts with flock management. For adult sheep, one of the most practical steps is careful feed control. Avoid moldy, spoiled, or poorly fermented silage and baleage, and discard feed that smells off, has visible spoilage, or was stored in a way that allowed air leaks. Clean feed bunks regularly and reduce contamination with manure, mud, and decaying organic material.

For lambs, focus on strong early immunity and sanitation. Good colostrum intake, clean lambing areas, prompt navel care when recommended by your vet, and quick treatment of pneumonia, diarrhea, or navel infections can reduce the risk of bloodstream infection reaching the central nervous system. Any sheep showing atypical behavior, weakness, or isolation should be removed from the flock promptly for evaluation.

Biosecurity matters too. Quarantine incoming animals, limit stress during transport and weather swings, and work with your vet on a flock health plan that includes nutrition, parasite control, vaccination where appropriate, and a response plan for neurologic disease. If a sheep dies with unexplained neurologic signs, necropsy can be one of the most cost-effective prevention tools because it may identify a feed problem, infectious risk, or reportable disease concern before more animals are affected.