403 



In the same manner a strong tendency to laminitis is induced in 

 horses on sea voyages, the exhaustion of the laminae resulting from the 

 continual constrained position which the animal is compelled to main- 

 tain on account of the rocking motion of the vessel. 



The same cause exists where one foot has been blistered, or where 

 one limb is incapacitated from any other reason ; for the opposite mem- 

 ber being called on to do double duty, soon becomes exhausted, and con- 

 gestion, followed by inflammation, results as a matter of course. Where 

 one foot only becomes laminitic, it is customary to find the other or 

 corresponding member participating at a later date, not always because 

 of sympathy, but because the transfer of all the functional performance 

 to the one foot proves within itself a sufficient exciting cause. 



(4) Rapid changes of temperature act as an exciting cause of lami- 

 nitis in precisely the same way as they act to produce disease in other 

 tissues, the result of these variations of temperature showing itself 

 upon those parts rendered particularly susceptible to pathological 

 changes from some impairment of their natural disease-re§isting powers. 



This change of temperature may be iuduced by drinking large quan- 

 tities of cold water while in an overheated condition. Here the internal 

 heat is rapidly reduced, the neighboring tissues and blood-vessels con- 

 strained, and the blood supply to these organs greatly diminished, 

 while the quantity sent to the surface is correspondingly increased. 

 True, in many of the cases which result from this cause there has not 

 been sufficient labor performed to impair the powers of the laminae, and 

 I am inclined to the opinion that laminitis is the more readily induced 

 than congestion or inflammation of the skin or other surface organs 

 because of the impossibility upon the part of the laminae to relieve 

 themselves of the threatened congestion by the general safety-valve of 

 perspiration. A cold wind or relatively cold air allowed to play upon the 

 body when heated and wet with sweat has virtually the same result, for 

 it arrests evaporation and rapidly cools the external surface, thereby de- 

 termining an excess of blood to such organs and tissues as are protected 

 from this outside influence. In many instances this happens to be some 

 of the internal organs, as the lungs, where the previous work has been 

 rapid and their functional activity impaired ; but in numerous other 

 instances the determination is toward the feet, and that it is so depends 

 upon two very palpable facts; first, that these tissues have been greatly 

 excited and are already receiving as much blood as they can accommo- 

 date consistently with health ; secondly, even though these tissues 

 are classed with those of the surface, their protection from atmospheric 

 influences by means of the thick box of horn incasing them renders 

 them in this respect equivalent to internal organs. 



Airain, a still more limited local action of cold excites this disease, 

 as seen from driving through water or washing the feet or legs whUe 

 the animal is warm or just in from work. Here a very marked reaction 

 takes place in the surface tissues of the limbs, and passive congestion 



