seventh cranial nerve; note position of lip.]

[Illustration: FIG. 27.--Bilateral facial paralysis. This colt was affected
with facial paralysis when born.]

CONGESTION AND ANAEMIA OF THE BRAIN.--In congestion of the brain, the
blood-vessels distributed to the nerve tissue become engorged with blood.
It may be either active or passive.

_The cause of anaemia_ of the brain is an insufficient blood supply. This
may be due to an abundant haemorrhage and cardiac weakness caused by shock
or organic heart disease.

_The causes of congestion_ of the brain are faulty methods of care and
feeding. It sometimes occurs when horses are shipped in poorly ventilated
cars, or kept in close stables. Climatic changes, or changing the stable
and feed, may cause it. Extremely fat animals and animals that are rapidly
putting on fat are predisposed to this disorder. Improper methods of
feeding, lack of exercise, constipation and excitement are the most common
causes. Passive congestion may result from pressure on the jugular vein by
obstructing the flow of blood from the brain, and raising blood pressure in
the blood-vessels of the brain. It is sometimes caused by organic heart
trouble.

_The symptoms_ come on very suddenly in congestion of the brain. The
disease may manifest itself as soon as the animal is moved out of the stall
or bed, or it may come on while it is feeding. In slight cases, the animal
appears excited and restless, the eyes are bright, the pupils are dilated,
and the pulse beats and respirations quickened. If the animal is moving
about, it may stop suddenly and show marked symptoms of a nervous disorder,