Listeriosis in Ox: Circling Disease and Brainstem Infection in Bovines

Listeriosis is a serious bacterial disease caused most often by Listeria monocytogenes. In oxen and other cattle, the best-known form is circling disease, a brainstem infection that causes asymmetric neurologic signs such as circling, head tilt, facial droop, and trouble eating or swallowing.

The bacteria commonly enter through the mouth and may travel along cranial nerves to the brainstem. That is why affected cattle often show one-sided nerve problems rather than generalized weakness at first. Merck Veterinary Manual notes that the disease in cattle is usually less sudden than in sheep or goats, but it is still an emergency because animals can worsen quickly.

Listeriosis can also matter for herd health and human health. The organism survives in the environment and can be associated with contaminated feed, especially poor-quality silage. Because Listeria is zoonotic, anyone handling saliva, tissues, aborted material, or raw milk from a suspect animal should use gloves, good hygiene, and guidance from their veterinarian.

Listeriosis is caused by infection with Listeria monocytogenes. In cattle, the disease is classically associated with spoiled, moldy, or poorly fermented silage, especially when silage pH is not low enough to suppress bacterial growth. Merck Veterinary Manual describes poor-quality silage as a major risk factor, and Cornell dairy guidance also highlights improperly fermented silage as an important source of exposure.

The bacteria are widespread in soil, water, feces, and decaying plant material, so exposure can happen even outside obvious outbreaks. Many animals in a herd may be exposed, but only a few develop clinical disease. Mouth abrasions from coarse feed may help the organism invade local tissues and then move along cranial nerves toward the brainstem.

Cases are often seen in cooler months when silage feeding is common, but listeriosis is not limited to winter. Stress, feed changes, poor bunk hygiene, and any situation that increases intake of spoiled feed may raise risk. Because Listeria can also contaminate milk and tissues, careful handling and sanitation are important around suspect animals.

Your vet will usually start with the history and neurologic exam. In cattle, listeriosis is often suspected when there is asymmetric brainstem dysfunction along with depression, circling, head tilt, facial paralysis, reduced eyelid function, or trouble prehending feed. Feed history matters too, especially recent use of questionable silage.

Definitive confirmation is harder in a live animal. Merck Veterinary Manual notes that diagnosis is often based on the typical neurologic pattern, while confirmation can come from bacterial culture or immunofluorescence testing. Cerebrospinal fluid may show increased protein and a mild mononuclear pleocytosis, but those findings support inflammation rather than proving Listeria by themselves.

If an animal dies or is euthanized, brain tissue is the preferred sample for confirmation. Your vet may also recommend necropsy, feed evaluation, and culture of suspect silage to help protect the rest of the herd. Differential diagnoses can include rabies, polioencephalomalacia, lead poisoning, thrombotic meningoencephalitis, vestibular disease, and brain abscesses, so isolation and safe handling may be advised until the picture is clearer.

Prevention centers on feed quality. Do not feed visibly spoiled, moldy, or poorly fermented silage. Remove refused feed promptly, keep bunks and feeding areas clean, and pay attention to silage packing, sealing, and face management so oxygen exposure stays low. Cornell dairy guidance emphasizes that improperly fermented silage is a key risk for Listeria contamination.

Work with your nutritionist and your vet if silage quality is inconsistent. Silage with a lower, stable pH is less supportive of Listeria growth than poorly preserved forage. Any sudden cluster of neurologic signs should trigger an immediate feed review and removal of suspect material while your vet investigates.

Good general hygiene also helps. Limit manure contamination of feed and water, isolate suspect animals, and use gloves when handling saliva, tissues, or aborted material. Because Listeria is zoonotic and can contaminate raw milk, families and farm staff should avoid consuming unpasteurized milk from suspect or sick animals and should wash hands and equipment thoroughly after contact.