252 STABLE MANUAL AND HORSE DOCTOR 



reasoning, experience, and investigation. Their origin 

 may be conveniently divided into : (1) Accidental ; 

 (2) Spontaneous ; (3) S^^mpathetic. 



1. Accidental. — In this case the exciting cause is gener- 

 ally evident enough, and usually a foreign body, which 

 produces mechanical or chemical irritation. 



Mechanical injuries comprise wounds and contusions 

 and abrasions of all sorts, sprains, dislocations, and 

 fractures, undue exertion of any part or organ, or the 

 body altogether, which, in hunter's phrase, is called being 

 " over-marked." 



Ghemiical excitants comprise all such substances as pos- 

 sess properties of an acrid, or corrosive, or poisonous nature ; 

 these are the mineral acids, the caustic alkalies, the metallic 

 salts, and every caustic or irritant which we are in the habit 

 of using in practice. 



The state of the atmosphere, heat and cold, moisture and 

 dryness, all in their turn become excitants of inflammation ; 

 their mischievous agency residing more in the vicissitudes 

 from one state to its opposite, than in any obnoxiousness in 

 our climate from their excess or continuance. Generally 

 speaking, horses turned out from warm stables and exposed 

 at once to the open air, even during the inclement seasons 

 of the year, seldom " take cold," or experience any direct 

 inflammation from the change ; though the reverse of this 

 vicissitude cannot be practised without such danger, and 

 especially with young horses. Cold, without wet, even 

 though alternated with heat, is not found to be nearly so 

 prejudicial as when moisture is present too. Hence we are 

 in the habit of viewing frosty weather as a season of health 

 among horses ; and hence it is that the spring and autumnal 

 months are the m.ost unhealthy, the weather then being 

 moist and variable, and the wind generally in a cold quarter. 

 Independently of these changes, there are conditions of the 

 atmosphere not understood, which, when they prevail, are 

 apt to produce an epizootic fever among horses, which has 

 been called " influenza." 



Animal Poisons, as well as natural ones, are found to be 

 occasionally suspended in the atmosphere, and through its 

 medium produce their effects. The air of a hot and ill- 

 ventilated stable may prove an excitant of inflammation, 

 not only from its high temperature, but also from the 

 noxious effluviae with which it has become impregnated 



