_Diagnosis_ is largely based on the suddenness of the attack, on the occurrence of high temperature before the seizure, not after as it is liable to be, if at all, in apoplexy, on the dark congestion of the mucosæ, and of the venous system, on the rapidity and shallowness of the respirations, on the tumultuous action of the heart, and on the general loss of sensory and especially of motor function, in circumstances calculated to induce sun-stroke. Localized paralysis or spasm would suggest the formation of a cerebral effusion or clot. _Prevention._ This will depend on the class of animal and its conditions of life and work. In horses care should be taken to regulate the work by the heat of the season and condition of the animal. When the temperature ranges from 80° to 100° F. the work should be lessened and every attention should be given to maintain the healthy functions (bowels, kidneys, skin) in good working condition. If the horse is young, fat, or out of condition from idleness or accumulation of fat he must have the greater consideration. So it is with a horse recently come from a colder latitude, and with a heavy draught horse that may be called on to do rapid work. Some protection is secured by wearing a sunshade or a wet sponge over the poll, and much may be expected from an occasional rest in the shade, a swallow of cool water and sponging of the head. Very heavy fat cattle should not be driven far nor shipped on the hottest days, and the packed car should not be left in the full sunshine in a still atmosphere. Yards with sheds under which they can retreat must be secured if possible. The heavily fleeced sheep must have equal care and the pastures for fat sheep and cattle should have available shade in form of trees, walls or sheds. Access to water is an important condition. _Treatment._ In slight cases (_overheated_) a few days of rest, under an awning rather than in a close stable, with a restricted and laxative diet. In severe thermic fever the first consideration is to lower temperature. If available turn a hose on the head, neck and entire body for five or ten minutes, or until the rectal temperature approaches the normal. In the absence of such a water supply, dash cold water from a well on the body but especially the head and neck, and if available tie a bag of ice around the poll. Active friction to the legs and body is often of great advantage. A large dose of antipyrin or acetanilid may be given hypodermically. On the other hand stimulants, and especially carbonate of ammonia, or sweet spirits of nitre may be given as an enema. This may be repeated in an hour in case the pulse fails to acquire force and tone. Should the temperature rise again later it may often be kept in check by cold sponging and scraping followed by rubbing till dry. In case of continued elevation of temperature, with heat of the head, and perversion of sensory or motor functions, meningitis may be suspected and appropriate treatment adopted.