DISEASES OF THE FETLOCK, ANKLE, AXD FOOT. 441 



Sinci? ringbone is considered to be one of the hereditary diseases, no 

 animal suffering from this trouble should ever be used for breeding 

 purposes. 



LAMINITIS, OR FOUNDER. 



Laminitis is a simple inflanmiation of the sensitive laminae of the 

 feet, characterized by the general phenomena attending inflamma- 

 tion of the skin and mucous membranes, producing no constitutional 

 disturbances except those dependent upon the local disease, and hav- 

 ing a strong tendency, in severe cases, to destructive disorganization 

 of the tissues affected. 



Causes. — The causes of laminitis are as wide and variable as in any 

 of the local inflammations, and may be divided into two classes — ^the 

 predisposing and the exciting. 



Predisposing causes. — From personal observation I do not know 

 that any particular construction of foot or any special breed Of horses 

 is predisposed to this disease, neither can I find anything to warrant 

 the assumption that it is in any way hereditary; so that while.. we 

 may easily cultivate a predisposition to the disease, it does not origi- 

 nate without an exciting cause. Like most other tissues, a predispo- 

 sition to inflammation may be induced in the sensitive liaminse by any 

 cause which lessens their power of withstanding the work imposed 

 on them. I'lt exists to an extent in those animals unaccustomed to' 

 work, particularly if they are plethoric, and in all that have been 

 previous subjects of the disease, for the stime rule holds good here 

 that we find in so many diseases — i. e., that one attack impairs the 

 functional activity of the affected tissues and renders them more easy 

 of a subsequent inflammation. Unusual excitement by determining 

 an excessive blood supply, bad shoeing, careless paring of the feet by 

 removing the sole support, and high calkings without corresponding 

 toe pieces must be included under this head. 



Exciting causes. -^Tlae, exciting cavises of laminitis are many and 

 varied. The most common are concussion, overexertion, exhaustion, 

 rapid changes of temperature, ingestion of certain feeds, purgatives, 

 and the oft-mentioned metastasis. 



(1) Concussion produces this disease by local overstimulation. 

 The excessive excitement is followed by an almost complete exhaus- 

 tion of the functional activity of the laminated tissues, the exhaustion 

 by congestion, and eventually by inflammation. But congestion here, 

 as in all other tissues, is not necessarily followed by inflammation; 

 for, although the principal symptoms belonging to true laminitis are 

 present, the congestion may be relieved before the processes of inflam- 

 mation are fully established. This is the condition in the many so- 

 called cases of laminitis which recover in from 24 to 48 hours. They 

 should be called congestion of the laminae. 



