In the intervals between attacks tonics and general hygiene should be invoked to build up the weakened nervous system. Quinine, and salts of iron, zinc or silver with a nourishing diet and out door exercise are especially indicated.
INSOLATION. HEAT EXHAUSTION. SUNSTROKE. THERMIC FEVER.
Definition: two forms. Heat exhaustion. Causes: prolonged heat, and moisture, overexertion. Impaired vaso-motor centre. Failing heart. Carbon dioxide poisoning. Symptoms: weak, fluttering pulse, perspiration, muscles flaccid, prostration, no hyperthermia. Treatment: stimulant, digitalis, digitalin, subcutem, nitro-glycerine, warm baths. Thermic fever. Hyperthermia excessive. Causes: insolation, prolonged heat and impure air, furnace heat, moist and dry heat, electric tension, overwork, muscular exhaustion, coagulation of myosin, constant heat on one part (head), excess of carbon dioxide, stiffening of bodies when killed in hot weather, debility, weakness, fatigue, chest constriction, tight girths or collars, short bearing reins, plethora, obesity, open cars and yards, fever, privation of water, heavy fleece. Lesions: right heart and systemic veins full, blood black fluid or diffluent, left ventricle empty, congested meninges, effusions in or on brain, or hæmorrhages. Symptoms: horse: dull, stupid, stubs toes, sways quarters, droops head, hangs on bit, props on feet, breathes rapidly, pants, stertor, dilated nostrils, gasping, fixed eyes, dilated pupils, tumultuous heartbeats, gorged veins, epistaxis, perspiration, convulsions: ox: parallel symptoms: sheep: open mouth, stertor, fixed eyes, pupils dilated, panting, swaying, fall, convulsions: dog: dull, prostrate, pants, congested veins and mucosæ, weakness, spasms, syncope, speedy rigor mortis. Overheating. Diagnosis: early excessive hyperthermia, venous congestion, shallow panting breathing, violent heart action, loss of sensory and motor functions, convulsions. Prevention: avoid violent, prolonged heat, and exertion, especially in case of fat animals or those new to hot climate, keep emunctories acting, shade head, water on head and to drink, protect fat cattle, shear sheep, water. Treatment: shade and laxatives; if severe, cold water from hose, ice bags to poll, rub legs, acetanilid subcutem, stimulant enemata, later mineral tonics, iron or zinc.
Definition. A morbid condition produced by the exposure to extreme heat, and marked by profound disorder of the vaso-motor and heat centres.
The single term of sun-stroke or heat-stroke has been replaced by two,—heat exhaustion and sun-stroke, indicating two distinct conditions, brought about by exposure to heat and manifested by different states of the body and distinctive symptoms.
Heat Exhaustion.
This appears as an exaggerated form of the general sense of relaxation, weakness and languor which follows on prolonged violent exertion in a hot atmosphere. There is more or less impairment of the vaso-motor nerve centre in the medulla, relaxation of the capillary system, and flagging of the heart’s action, which loses its customary stimulus, by reason of the defective supply of blood returned by the veins. This may become so extreme that the patient dies by syncope. In other cases the paresis is mainly shown in the vaso-motor system, and its centres in the medulla, the blood is delayed in the distended capillaries and veins, it becomes overcharged with carbon dioxide, the heart’s action is accelerated and feeble, the pulse rapid, weak and fluttering, perspiration breaks out on the skin, and the temperature is normal or subnormal. The muscular weakness, the flaccid condition of the facial muscles, and general depression suggest a state of collapse. This condition is not necessarily due to exposure to the intensity of the sun’s rays, but may come on in animals subjected for a length of time to artificial heat, and especially if the air is impure, and if the subject has to undergo severe physical exertion.
Treatment. In slight cases of this kind a stimulant is usually desirable and ammonium carbonate in bolus or solution will usually serve a good purpose. In its absence alcohol or spirits of nitrous ether may be given. Digitalis is of great value in sustaining the flagging action of the heart and has the advantage that as digitalin it can be given hypodermically when it is impossible to give ammonia, alcohol or ether by the mouth. For the same reason nitro-glycerine may be resorted to, or even atropia as a vaso-motor stimulant. Active friction of the body and limbs will aid circulation and indirectly stimulate the heart, and in case of subnormal temperature it may be supplemented by a warm bath in the smaller animals, kept up until the normal temperature in the rectum has been restored.
Thermic Fever. Sun-stroke.
This is readily distinguished from heat exhaustion by the predominance of the hyperthermia. While in heat exhaustion the temperature is usually subnormal, in sun-stroke it is excessive, (108°–113° F.).