SUNSTROKE. 569 



this country only, but wherever horses are employed for draught. 

 In the laxge majority of cases, it occurs only when the horse is at 

 work in draught. In some rare instances, the attack is due to 

 brain disease, and will then, more or less, resemble epilepsy, 

 which comes on, at fairly regular intervals of time, with little or 

 no warning, and is accompanied by convulsions and loss of 

 consciousness. The term megrims, in human medicine, signifies a 

 form of headache which appears in paroxysms. 



SYMPTOMS. — The attack commences suddenly. The horse 

 throws his head about ; stops, if previously in movement ; staggers, 

 and even falls. There is marked fulness of blood in the head ; 

 quickened breathing ; and, often, loss of consciousness and 

 convulsions. 



The TREATMENT is self-suggestive — if the seizure be brought 

 on by pressure of the coUar — ^to remove the offending gear ; 

 and to " cool " the animal down with laxative food, and a mild 

 dose of physic, if necessary. The case hardly admits of treatment, 

 if the complaint be due to nervous disease; for, in the horse, at 

 least, " practical soundness,'' is required and not mere prolongation 

 of life, as might be sufficient in hvmian practice. Even for stud 

 purposes, an animal afflicted with brain disease, would scarcely be 

 worth keeping ; considering the marked influence of heredity in 

 this complaint. 



Sunstroke. 



DEFINITION. — A state of . sudden unconsciousness and para- 

 lysis brought on by exposure to great atmospheric heat, generally 

 intensified by muscular exertion. 



NATURE OF THE DISEASE.— In human medicine, there are three 

 forms of sunstroke recognised : (1) Heat exhaustion, causing failure of the 

 action of the heart. (2) Heat shock, coup de soleil, oi sunstroke proper, 

 in which, exposure to great heat, often aided by intense glare, appears to 

 paralyse the nerve centres of breathing and of blood circulation by sudden 

 shock^ so that the lungs and heart are unable to perform their functions. 

 (3) Heat fever or heat apoplexy, in which the nerve centres become 

 exhausted from over-stimulation due to prolonged exposure to heat. We 

 have good reason to believe that the temperature of the body is regulated 

 by a heat centre in the nervous system. As nerves become insensible to a 

 stimulus by which they have been highly excited for a long period, we 

 may account for the sudden rise in temperature and consec[uent climax in 

 cases of heat apoplexy, by supposing that great and continued heat had 

 so over-stimulated the heat centre, that it had at last lost its power of 

 control, with the result that the temperature rises to such an extent as to 

 arrest the action of the lungs and heart, to a greater or less degree. I 

 believe ev*ery one of the scores of cases of sunstroke which I have seen 

 among horses in hot climates, came under the heading of heat apoplexy. 



