THROMBOSIS. 365 



detracts from a horse's claim to soundness can not for a moment be 

 denied. 



Cause. — Veterinarians and pathologists are yet in doubt in respect 

 to the cause of this affection, as well as to its essential nature. 

 Whether it results from disease of the hock, of an ulcerative charac- 

 ter ; whether it springs from a malformation ; whether it is a short- 

 ening of the ligaments, a chronic inflammation of the sciatic nerve, or 

 a disease of the spinal cord ; whether it is purely a muscular or purely 

 a nervous lesion, or a compound of both — it still continues, if an 

 etiologist is bound to possess universal knowledge within the scope of 

 his special studies, to be his opprobrium and his puzzle. 



Treatment. — When there is a known or suspected cause the treat- 

 ment should be directed toward this factor. If due to local inflamma- 

 tion of the hock or foot, only this local lesion should be treated. If 

 it remains after the local lesion has healed, or if we have no assignable 

 cause, the best results have followed the sectioning of the lateral 

 extensor of the foot. A competent veterinarian alone should under- 

 take this operation. 



THROMBOSIS. 



There are certain forms of lameness which are very peculiar in their 

 manifestation, and which to the nonprofessional mind must appear to 

 belong to the domain of mystery or theory instead of occupying a 

 well-established position among the subjects of equine pathology. 

 Yet they are no less susceptible of actual demonstration and of pos- 

 itive comprehension than many facts which, plain and familiar to the 

 general understanding now, were once ranked among things occult 

 and unsearchable. A thrombus, considered as a cause of lameness, 

 may find a place among these understood mysteries. 



Cause. — Under certain peculiar conditions of inflammation of the 

 blood vessels, and also in aneurisms, clots of blood are sometimes 

 formed in the arteries and find their way in the general circulation. 

 At first, while very small, or sufficiently so to pass from one vessel to 

 another, they move from a small vessel to a larger, and from that to 

 one still larger, constantly increasing in size until at some given point, 

 from their inability to enter smaller vessels, their movement is 

 finally ax'rested. The artery is thus effectually dammed, and the clot 

 in a short time cuts off completely the supply of blood from the parts 

 beyond. This is thrombosis, and it often gives rise to sudden and 

 excessive lameness of a very painful character. 



Symptoms. — Thrombi may form in any of the arteries of the body, 

 and doubtless have been the cause of many cases of lameness which 

 could never be accounted for. If they exist in small arteries their 

 diagnosis will probably fail to be made out with certainty, but when 

 situated in the larger trunks a strong suspicion of their presence may 

 be excited. In some cases they may even be recognized with posi- 

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