lameness: its caisks and i isia imknt. 391 



thrombosis. 



Tlicre lilt' certain forms of lameness which are \ery jH.'cuIiar in 

 theii- manifesttttion, and which to the nnnprofessional mind must 

 appear to belonjr to the domain of njystery or theory instead of oc- 

 cupying u well-establisljed position anion*; the subjects of equine 

 patholoiry. Vet they are no less susceptible of actual demonstration 

 and <d" positi\e coniprchfiision thiui many facts whidi, plain and 

 familiar to the fieneral understanding now, were once ranked among 

 things occult and unsearchable. A throml)Us. considered as a cause of 

 lameness, may find a place among these undeistood mystei'ies. 



('<ntf<c. — Under certain peculiar conditions ai inflammation of the 

 bl(X)d 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 siifliciently 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 tlieii- inability to enter smaller vessels, their movement is 

 finally arrested. The artery is thus effectually (himmed, and the clot 

 in a short time cuts off completely the sui:)i)ly of blood from the parts 

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

 exces.sive lameness of a very painful character. 



'^iimptomx. — Thrombi may form in any of the arteiies, and doubt- 

 le.ss have been the cause of many ca.ses 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 jire.sence may be excited- 

 Tn some cases they may even be recognized with possitive accuracy, 

 as when the vessels which supply the posterior extremities are aflFected 

 by the blocking up of the posteiior aoita or its ramifications. 



The exis-tence of thrombosis of the arteries of the hind leg may 

 always l)e suspected when the following history is known: The gen- 

 eral health of the animal is good, but symptoms of lameness in one of 

 the legs have been <leveloped, becoming more marked as he is worked, 

 and especially when driven at a fast gait. But the disturbance is not 

 permanent, and the lameness di.sai)pears almost imme<liately after a 

 rest. There is an increase of tlie difliculty, however, and. though the 

 aniuii^l may walk normally, he will, when made to trot, verv soon 

 l>egin to slacken his pace and to show siirnx of the trouble, and if 

 urgefl to increase his speed will become lamer and lamer; an abundant 

 perspiration will break out; he will refu.se to go. and if forced he 

 shows we^iknesH behind, seems ready to fall, and perhai)s does fall. 

 ^^'hile on his feet the leg is kept in con.stant motion, up and down, 

 and is ke]>t from the ground as if the contact were too painful to 

 bear. If undi.sturbed this .series of .symjitoms will gradually .subside, 

 sometimes very soon, and occasionally after a few hours he will 



