572 NERVOUS DISEASES. 



observed that horses which perspire little, are specially liable 

 to sunstroke. Excitable, hard-pulling horses will naturally be 

 more apt to suffer from heat exhaustion than more placid-tempered 

 animals. 



PREVENTIVE MEASURES.— The predisposing causes should 

 be guarded against. Before taking a horse out to work in a 

 climate and during weather in which sunstroke is liable to occur, 

 his breathing and general state should be observed. If he be seen 

 to "blow," he should be put back, and treated as the case may 

 demand. On a journey, under similar conditions, any unusually 

 quickened breathing and unwonted depression should at once be 

 attended to. In such instances the clinical thermometer (p. 691) 

 will be very useful. A rise of say 5° F. will point to the existence 

 of serious danger. Horses which have to work in the sun, like 

 those on tramways, should have short stages, and be watered 

 immediately after doing their turn. Probably the best mechanical 

 protection for animals at work in the sun is a thick shade (of 

 wood or stout leather, for instance) for the eyes and forehead. 

 There is no doubt that the effect of intense glare on the retinee 

 of the eyes is a potent aid in bringing on an attack of sunstroke. 

 In. our own cases, we may experience the great relief and actually 

 cooling effect of blue, green, or neutral-tinted glasses when worn 

 in the open on a very hot and sunshiny day. The retina, which 

 is an expansion of the optic nerve and close to the brain, is 

 peculiarly sensitive to heat rays as well as light rays. Also, the 

 brain is nearer the surface at the forehead, than at any other 

 part of the head. Pith sun-protectors placed over the top of 

 the head and poll, and over the loins, as is often done in India, 

 are of little value in guarding against sunstroke, as compared 

 to that of thick shades for the eyes and forehead. The sun- 

 bonnets used during summer on horses in England, give no pro- 

 tection against sunstroke ; for they do not shade the eyes and 

 forehead, and are far too thin. Everyone who has travelled, 

 knows that a straw hat is not of the slightest use for shielding 

 the head against the rays of the sun in the tropics, for which 

 object a thick head covering of a material that is a bad conductor 

 of heat (such as a turban or pith helmet) is indispensable. When 

 horses, by the fact of their " blowing " without having been 

 worked, and being out of spirits without cause, are seen to bear 

 hot weather badly, special precautions should be taken with them. 

 It will be found that such animals will generally have an un- 

 usually hot skin, and will perspire with difficulty ; in fact they 

 will be feverish. They should have a plentiful supply of salt 

 (p. 605) and may, from time to time, get an ounce of bicarbonate 



