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diseased than the mucous membrane of any other part of the body. 

 The sinuses of the head are compartments which communicate with the 

 nasal chambers and are lined with a continuation of the same mem- 

 brane that lines the nasal chambers; their presence increases the 

 volume and modifies the form of the head without increasing- its weight. 



The horse, in a normal condition, breathes exclusively through the 

 nostrils ; uo^air passes through the mouth in respiration. This is one 

 reason why horses probably are affected oftener with colds than other 

 animals. The organs of respiration are more liable to disease than the 

 organs connected with any other function of the animal, and, as many 

 of the causes can be prevented, it is both important and profitable to 

 know and study the causes. The respiratory surface iu the lungs of 

 the horse is estimated to be from 200 to 500 square feet. 



The cause of many of the diseases of these organs may be given under 

 a common head, because even a simple cold, if neglected or badly 

 treated, may run into the most complicated lung disease and terminate 

 fatally. In the spring aud fall, when the animals are changing their 

 coats, there is a marked predisposition to contract disease, and conse- 

 quently care should be taken at those periods to prevent other exciting 

 causes. 



Badly ventilated stables are a frequent source of disease. It is a great 

 mistake to think that country stables necessarily have purer air than 

 city stables. Stables on some farms are so faultily constructed that it 

 is almost impossible for the foul air to gain an exit. All stables should 

 have an unlimited supply of jiure air, and be so arranged that strong 

 draughts can not blow directly on the animals. Hot stables are almost 

 always illy ventilated, and the hot stable is a cause of disease on account 

 of the extreme change of temperature a horse is liable to when taken 

 out, and extreme changes of temperature are to bo avoided as certain 

 causes of disease. A horse taken from pasture and kept in a hot stable 

 is almost sure to contract a cold : the stable should be thrown open and 

 the temperature gradually increased in such cases, when practicable, to 

 avoid the sudden change. 



A cold, close stable is invariably damp, and is to be avoided as much 

 as the hot, close, and foul stable. Horses changed from a cold to a warm 

 stable are more liable to contract cold than when changed from a warm 

 to a cold stable. Pure air is more essential than warmth, and this fact 

 should be especially remembered when the stable is made close and foul 

 to gain the warmth. It is more economical to keep the horse warm with 

 blankets than to prevent the ingress of pure air in order to make the 

 stable warm. 



Stables should be well drained and kept clean. Some farmers allow 

 dung to accumulate in the stalls until there is hardly sufficient room for 

 the horses. This is a pernicious practice, as the decomposing organic 

 matter evolves poisonous gases that are predisposing or exciting causes 

 of disease. "When a horse is overheated it is not safe to allow him to 



