8

MENINGITIS

Inflammation of the meninges occurs most commonly as a complication of
a pre-existing disease.
Meningitis is usually associated with a bacterial infection and is manifested clinically by fever, cutaneous hyperesthesia, and rigidity of muscles.

ETIOLOGY

Most Significant meningitides are bacterial, although most viral encephalitides
have some meningitic component.

Cattle

Viral diseases - bovine malignant catarrh, sporadic bovine encephalomyelitis
Bacterial diseases - listeriosis,
H. somni, rarely tuberculosis.
Horses
- Strangles, Pasteurella haemolytica
-Streptococcus equi, Actinomyces spp.
Sheep
Listerosis
S. aureus (tick pyemia) in newborn lambs
Mannhemia (Pasteurella) haemolytica in lambs.


PATHOGENESIS

Inflammation of the meninges causes local swelling and interference with

blood supply to the brain and spinal .
The signs produced by meningitis are thus a combination of those resulting from
irritation of both central and peripheral nervous systems. In spinal meningitis
there is muscular spasm with rigidity of the limbs and neck, arching of the back
and hyperesthesia with pain on light touching of the skin. When the cerebral
meninges are affected, irritation signs, including muscle tremor and convulsions,
are the common manifestations. Since meningitis is usually bacterial in origin,
fever and toxemia can be expected if the lesion is sufficiently extensive.
Defects of drainage of CSF occur in both acute and chronic inflammation of the meninges and produce signs of increased intracranial pressure. The signs are general, although the accumulation of fluid may be localized to particular sites
such as the lateral ventricles.
CLIN ICAL FINDINGS

Acute meningitis usually develops suddenly and is accompanied by fever and toxemia in addition to nervous signs.
There is trismus, opisthotonos, and rigidity of the neck and back. Motor irritation signs include tonic spasms of the muscles of the neck ,causing retraction of the head, muscle tremor and paddling movements.

There may be a disturbance of consciousness manifested by excitement or mania in the early stages, followed by drowsiness and eventual coma.
Blindness is common in cerebral meningitis, but not a constant clinical finding.


TREATMENT

The infection is usually bacterial, and parenteral treatment with antimicrobial

Large doses daily for several days are required.
Antimicrobial agents
The parenteral treatment with the antimicrobial of choice, determined by a
susceptibility test, does not result in a beneficial response in 3-5 days the
prognosis is unfavorable.

The response to therapy will depend on the causative pathogen and the

severity of the inflammation present.

The choice of antimicrobial agent will depend on the suspected cause of

the meningitis. The common antibiotics, such as penicillin and oxytetracycline,
are effective for the treatment of meningoencephalitis in cattle due to H. somni when treatment is begin early.