416 BUREAU OF ANIMAL INDUSTRY. 



Truo, in many cases there has not been sufficient labor performed to 

 impair the powers of the laminre, and laminitis is more readily induced 

 than congestion or inflammation of the skin or other surface organs, 

 because the lamina? can not relieve themselves of threatened conges- 

 tion by the general saf et}^ valve of perspiration. A cold wind or rela- 

 tiveh' cold air allowed to pla}^ upon the body when heated and wet 

 with sweat has virtuall}- the same result, for it arrests evaporation and 

 rapidl}^ cools the external surface, thereb}^ determining 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, if 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 excit;^d and 

 are already receiving as much blood as they can acconmiodate consist- 

 ently with health; secondl}", 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. 



A more limited local action of cold may excite this disease, by driv- 

 ing through water or washing the feet and legs while 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 of the foot 

 results from an interference with the return flow of l)lood which is 

 being sent to these organs in excess. These are more apt to be sim- 

 ple cases of congestion, soon to recover, yet they maj^ 1)ecome true 

 cases of laminitis. 



(5) Why it is that certain kinds of grain will cause laminitis does 

 not seem to be clearl}' understood. Certainl}^ they possess no specific 

 action upon the lamina^, for all animals are not alike affected, neither 

 do they always produce these results in the same animal. Some of 

 these foods cause a strong tendency to indigestion, and the consequent 

 irritation of the alimentary canal may be so great as to warrant the 

 belief that the lamin?e are affected through sympathy. In other 

 instances there is no apparent interference Avith digestion nor evidence 

 of any irritation of the mucous membranes, yet the disease is in 

 some manner dependent upon -the food for its inception. Barley, 

 wheat, and sometimes corn are the grains most apt to cause this dis- 

 ease. With some horses there appears to be a particular suscepti- 

 bility to this influence of corn, and the use of this grain is followed by 

 inflammation of the feet, lasting from a few daj^s' to two weeks' time. 

 In these animals, to all appearances healthy, the corn neither induces 

 colic, indigestion, nor purging, and apparently no irritation whatever 

 of the alimentary canal. 



(6) Fortunately purgative medicines rarely cause inflanunation of 



