_Prevention._--In very hot weather horses should have wet sponges or light sunshades on the head when at work, or the head may be sponged with cold water as many times a day as possible. Proper attention should be given to feeding and watering, never in excess. During the warm months all stables should be cool and well ventilated, and if an animal is debilitated from exhaustive work or disease it should receive such treatment as will tend to build up the system. Horses should be permitted to drink as much water as they want while they are at work during hot weather.
An animal which has been affected with sunstroke is very liable to have subsequent attacks when exposed to the necessary exciting causes.
Apoplexy is often confounded with cerebral congestion, but true apoplexy always consists in rupture of cerebral blood vessels, with blood extravasation and formation of blood clot.
_Causes._--Two causes are involved in the production of apoplexy, the predisposing and the exciting. The predisposing cause is degeneration, or disease which weakens the blood vessel; the exciting cause is any one which tends to induce cerebral congestion.
_Symptoms._--Apoplexy is characterized by a sudden loss of sensation and motion, profound coma, and stertorous, difficult breathing. The action of the heart is little disturbed at first, but soon becomes slower, then quicker and feebler, and after a little time ceases. If the rupture is one of a small artery and the extravasation limited, sudden paralysis of some part of the body is the result. The extent and location of the paralysis depend upon the location within the brain which is functionally deranged by the pressure of the extravasated blood; hence these conditions are very variable.
In the absence of any premonitory symptoms or an increase of temperature in the early stage of the attack, we may be reasonably certain in making the distinction between this disease and congestion of the brain, or sunstroke.
_Pathology._--In apoplexy there is generally found an atheromatous condition of the cerebral vessels, with weakening and degeneration of their walls. When a large artery has been ruptured it is usually followed by immediate death, and large rents may be found in the cerebrum, with great destruction of brain tissue, induced by the forcible pressure of the liberated blood. In small extravasations producing local paralysis without marked general disturbance the animal may recover after a time; in such cases gradual absorption of the clot takes place. In large clots atrophy of the brain substances may follow, or softening and abscess from want of nutrition may result, and render the animal worthless, ultimately resulting in death.