415 



the laminated tissues, the exliaustioii by congestion, and eventually 

 by inflammation. But congestion here, as in all other tissues, is not 

 necessarily followed by inflammation ; lor although the principal symp- 

 toms belonging to true laminitis are present, the congestion ma}' be 

 relieved before the processes of inflammation are fully established. 

 This is the condition that obtains in the many so-called cases of lam- 

 initis, Avhich recover in fi'om twenty-four to forty-eight hours' time. 

 These are the cases which should be called congestion of the laminsc. 

 Laminitis from concussion is common in track horses trotting races 

 when not in condition, especially if they are carrying the obnoxious 

 toe Aveights, and in green horses put to work on city pavements to 

 which they are unaccustomed. Concussion from long drives on dirt 

 roads is at times productive of the same results, notably when the 

 weather is extremely warm, or at least when the relative change of 

 temperature is great. But undoubtedly the exhaustion so apt to be 

 produced under these circumstances must be considered as exerting 

 almost as great an influence as an exciting cause as does the long-con- 

 tinued concussion. This same combination of causes must also be 

 admitted as determining the disease when seen at times in hunters, 

 for the imi)osed weight of the rider increases the demands made upon 

 the function of these tissues, and their powers of resisting congestion 

 and its consequences are the sooner exhausted. 



(2) Overexertion, as heavy pulling or rapid work, even where there 

 is no chance for immoderate concussion, occasionally results in this 

 disease, although in the majorit}' of instances exhaustion is a con- 

 junctive cause, for overexertion can not be long continued without 

 inducing exhaustion. 



(3) Exhaustion, in whatever manner produced, is nearly as prolific 

 a source of laminitis as is concussion, for when the physical strength 

 has been greatly impaired, even though but temporarily, some part 

 of the economy is rendered more vulnerable to disease than others, 

 and it is not strange that in nian}"" instances it should be those parts 

 still called ujion to perform their function of maintaining the weight 

 of the body after their activity has been exhausted. It is to this cause 

 Ave must ascribe those many cases Avhich we see folloAving a hard day's 

 AA'ork, Avhere at no tijne has there been OA^erexertion or immoderate 

 concussion. 



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

 horses on sea A^oyages, the exhaustion of the laminje resulting from 

 the continual constrained position Avhich the animal is compelled to 

 maintain on account of the rocking motion of the A^essel, 



The same cause exists Avhere one foot has been blistei-ed, or AA^here 

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

 member being called on to do double duty, soon becomes exhausted, 

 and congestion, folloAved T)y inflammation, results as a matter of 

 course. Where one foot only becomes laminitic, it is customary to 



