Meningitis is inflammation of the membranes encapsulating the brain. In feedlot cattle in Australia, meningitis may occur following upper respiratory bacterial infection.
The bacterium most commonly involved is Histophilus somni. It can cause an acute, often fatal, septicaemic disease involving the respiratory, cardiovascular, musculoskeletal, or nervous systems, either singly or in combination. Affected cattle are usually found dead but may display premonitory nervous signs from thrombotic meningoencephalitis associated with septicaemic episodes.
Occasionally Mannheimia haemolytica and Pasteurella multocida, which usually cause a fibrinous pneumonia, may produce a localized fibrinopurulent leptomeningitis.
Listeria monocytogenes may proliferate under favour able conditions in spoiled silage or hay and then cause a pyogranulomatous meningoencephalitis in animals consuming the contaminated feed.
Animals with meningitis will show signs of central nervous system disease that may vary depending on the location, extent and severity of damage. Signs may include head tilt, circling, ataxia, hyperaesthesia, neck rigidity, blindness, seizures, coma and death.
At necropsy, examination of the meninges on the ventral brain may detect a diffuse infiltration of pus and congestion of blood vessels. The cerebrospinal fluid may be cloudy.
Specimens for the laboratory should include swabs of cerebrospinal fluid and meninges for bacteriology, and formalin-fixed brain for histology.
Differential diagnoses include lead poisoning and polioencephalomalacia.
Treatment of animals with signs of meningitis or encephalitis is often unrewarding and affected animals are likely to have a high risk of dying.
Treatments may include high doses of antibiotics (ceftiofur sodium, penicillin, florfenicol, oxytetracycline, erythromycin, or tylosin), and non-steroidal anti-inflammatory drugs (flunixin meglumine, ketoprofen, meloxicam, or tolfenamic acid).
Prevention largely depends on reducing stress, preventing respiratory disease and providing unspoiled feed.