Little seen in cattle. Acute and chronic cases. Miliary tubercles in
pia. Hydrocephalus. Progresses slowly. Irritability, hyperæsthesia,
photophobia, congested conjunctiva, grinding teeth, spasms, squinting,
dilated pupils, congested disc, drowsiness, stupor, coma, palsy.
Tubercle of the encephalon has been little noticed in the lower animals,
partly because it is especially a disease of early life, while animals
usually contract tubercle later in life, and partly because subjective
symptoms are inappreciable, and the cranium is seldom opened in post
mortem examinations. As the affection usually appears as a secondary
deposit, the tubercles elsewhere go a long way toward identifying the
nature of the disease in the brain. It has usually been found
consecutive to pulmonary tuberculosis.
In a case reported by Fischœder as seen at the Bromberg abattoir, in a
350 lbs. calf, the animal had shown weakness, stupor and a tendency to
fall toward the right. The brain lesions consisted of small foci of
tubercle on the posterior pillars of the fornix (trigone) and adjacent
parts. The left eye had on its inner aspect, near the junction of
sclerotic and cornea, a firm mass with tubercular centres, extending
inward as far as the retina. The bronchial mediastinal, prepectoral,
brachial and precrural glands were tuberculous.
In a case in a cow reported by Lesage there were unsteady gait, impaired
vision, and great timidity. Necropsy showed a suboccipital tubercle
extending into the frontal sinus and cranium, and invading the brain
near the parietal lobe for more than an inch. There were
retro-pharyngeal and pleural tubercles as well.
In a case of Routledge’s, with extensive recent exudate, the condition
advanced from apparent health to extensive paralysis in three days,
while in a case which the author obtained in slaughtering a tuberculous
herd no special nervous symptoms had been noticed during life. Much
therefore depends on the rapidity as well as the seat of development.
The primary lesions in the brain are of the nature of miliary tubercles
in the pia mater which becomes congested, rough, granular, and throws
out a free serous secretion. Thus hydrocephalus is a usual concomitant
of the affection.
The disease is characterized by its slow advance in keeping with gradual
increase of the tubercle and is thus distinguishable from the more acute
congestions and inflammations. The earlier stages are usually marked by
nervous irritability, hyperæsthesia, intolerance of light, closed
eyelids, congested conjunctiva, grinding of the teeth and even spasms
partial or general. The second stage shows somnolence, deepening into
stupor or coma, or there may be going in a circle or other irregular
movement. Squinting usually convergent, dilated pupils and congestion of
the optic disc frequently occur. The sleep, stupor, paralysis or coma
may set in early and is usually largely due to the amount of exudation
and the rapidity of its effusion.