10/28 - Brainstem, Cranial Nerves, Cerebellum

Brainstem

Lesions in which CNS component can produce respiratory depression, death, and decreased mental status? Associated CN signs can include gait/mentation/posture/spinal reflexes normal or abnormal. Common diseases include listeriosis, TME, otitis media/interna, and P. tenuis infection.

L. monocytogenes

What bacteria causes listeria in the brainstem, and is a gram positive bacteria that lives in the soil and can be found in feces, milk, and uterine discharges if the animal is shedding? Risks include silage, improper fermentation, spilled hay, grass clippings, coarse feed, bedding, and fomites. It can cause micro-abscesses in the brainstem, abortions, KCS, uveitis, hypopyon, silage eye, neonatal death, diarrhea, and mastitis. Fever, anorexia, and depression are common. The route of infection can be the trigeminal nerve, mouth lesions, and others. Diagnosis is based on history of exposure, clinical signs, CSF analysis for mononuclear cells (mononuclear pleocytosis), increased CSF protein, and postmortem (definitive). Culture is not useful. Treatment is with IV and then SC antibiotics for 2-4 weeks, long-acting oxytetracycline, NSAIDs, and support. Prognosis is good if ambulatory. Prevention is through reducing risk factors and pasteurizing milk.

H. somni

Which bacteria causes thrombotic meningoencephalitis (TME), and is a gram negative bacteria which is commensal in the mucous membranes and secretions? It is also called sleeper calf disease. Risks include shipping fever, venereal spread, and infection at birth. Signs include thrombosis/micro-abscesses of the brainstem, fibrinous pleuritis, bronchopneumonia, laryngitis, myocarditis, necrosis of the cardiac muscle, and vasculitis/thrombosis. Respiratory disease will appear first. Fever, anorexia, and depression are common. Route of infection is through the meninges post-pneumonia. Diagnosis is based on history, clinical signs, and neutrophilia/protein/hemorrhage on CSF analysis. CBC will show septicemia. Postmortem is the only definitive diagnosis. Treatment is with antibiotics IV then SC for 2-4 weeks, NSAIDs, and support. Prognosis is fair if caught early. Vaccines reduce respiratory disease risks but are not fully effective.

Otitis

What infective condition, whether media or interna can affect any species and is the most common cause for facial nerve paralysis in livestock? It can occur due to bacteria, mites, ear ticks, respiratory infections, extension from otitis externa, eustachian tubes, or hematogenous spread. Young animals are more often affected. Signs include head-shaking, foul discharge, VII signs, purulent discharge if the tympanic membrane is ruptured, and VIII signs, depending on whether it is externa, media, or interna. Diagnosis is presumptive based on cranial nerve and clinical signs, and ear swab can diagnose the agents. Treatment depends on the agent, including antibiotics, NSAIDs, myringotomy, ear canal ablation and tympanic bullae osteotomy. Control is by preventing ear parasites, pneumonia, and pasteurizing milk/colostrum.

P. tenuis

What species is known as the meningeal worm, and affects the brainstem and spinal cord? It is a regional disease caused by exposure to deer and clinical signs include ascending paralysis, recumbency, CP deficits, and variable BS/SC deficits due to aberrant migration. CSF analysis shows eosinophilia. Differentials include tick paralysis and CNS trauma/abscesses. Treatment is with fenbendazole, steroids, and support. Prevention is by reducing deer exposure and avermectins.

Cerebellum

Diseases affecting which CNS component presents with varying clinical signs depending on the area affected, but can include ataxia without paresis, hypermetria, wide-based stance, head intention tremor, nystagmus, abnormal menace reaction, and suckle reflex in juveniles? Disease can be developmental, plant toxicities, lysosomal storage diseases, hypomagnesemia, grass staggers, BVDV, border disease, and bluetongue.

Hypoplasia

Cerebellar what condition is most often associated with BVDV in cattle and occurs at 125-180 days of gestation? There will be hydrocephalus and ocular abnormalities, depending on the day of gestation (ocular occur later in gestation). Signs present at birth and it can be due either to natural infection or improper MLV vaccination of the dam.

Magnesium

Grass tetany is a cerebellar disease caused by deficiency of what mineral? This is when the bovine serum level is under 1.2 and the sheep serum level is under 0.5. There is a sudden onset of frenzy, rage, bellowing, and convulsions, and it occurs on poor or rapidly growing pasture. Treatment is with supplementation of this and calcium.

Rye

The cerebellar disease known as what grass staggers can occur either due to ingestion of grass and endophytes (seasonal, ryegrass and lolitrem B toxin), or locoweeds (swainsonine toxin)? The locoweed form causes multiple body system disease and there is no treatment. The grass/endophyte form can be treated by moving off pasture.