DISEASES OF THE HORSE. 365 



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

 it results from disease of the hock, of an ulcerative character; whether 

 it springs from a malformation; whether it is a shortening of the liga- 

 ments, 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 ver}^ 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 positive com- 

 prehension 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, the}^ move from a small vessel to a larger, and from that to 

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

 from their inability to enter smaller vessels, their movement is finally 

 arrested. The arter}^ is thus effectuall}^ dammed, and the clot in a 

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

 bej^ond. This is thrombosis, and it often gives rise to sudden and 

 excessive lameness of a ver}^ painful character. 



Symptoms. — Thrombi may form in any of the arteries of the bod}^, 

 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 positive 

 accuracy, as when the vessels which supply the posterior extremities 

 are affected by the blocking up of the posterior aorta or its ramifications. 



The existence of thrombosis of the arteries of the hind leg may 



