In very hot seasons horses which are called upon to undergo violent exertion are likely to suffer from cerebral derangement due to determination of blood to the vessels of the brain. This condition is correctly described as sunstroke.
According to the duration of the active causes the final consequences will vary. In the first instance, symptoms will consist of dulness, general depression varied by periods of excitement. If the causes continue, the voluntary movements of the animal may be interfered with, and finally it may fall in a state of unconsciousness. The worst consequence which is to be apprehended is the rupture of some of the overcharged vessels of the brain and escape of blood into the tissue of the organ. If the hemorrhage is sudden and considerable the result will be an apoplectic-fit, which may be immediately fatal. The fit will probably be preceded by an irregularity in the animal's movements, trembling, turning round or backing, ending in a sudden fall, loss of consciousness, and possibly death in a few minutes. A partial recovery may, however, take place, and the animal may live for some days or weeks, but a fatal result is almost certain to follow.
When the hemorrhage is slight the symptoms will be those which have previously been described, i.e. irregular movements followed by drowsiness, from which the animal will gradually recover, but in such instances a small clot of blood may be left in the substance of the brain and lay the foundation for future mischief.
On this subject a great difference of opinion exists; bleeding and cold applications are advocated, or, on the other hand, stimulants are suggested in order to overcome the drowsy and depressed state into which the animal has fallen. It is probably the case that ice-bags to the head and bleeding would be beneficial when the animal is suffering from an apoplectic fit, while the use of stimulants might be resorted to when the more urgent symptoms have ceased.
In all cases where the power to swallow exists, a strong dose of physic should be promptly administered.