414 DISEASES OF THE HORSE'S FOOT 



example, that of rheumatism) circulating in the blood- 

 stream. 



Pathology. — Uncomplicated acute synovitis never causes 

 death. The pathological changes in connection with it have 

 therefore been studied in cases purposely induced, and the 

 animal afterwards slaughtered. It is then found that, as 

 in inflammation elsewhere, the synovial membrane is show- 

 ing the usual inflammatory phenomena — that it is thick 

 and swollen as a result of the inflammatory hyperemia and 

 commencing exudation. Later, the synovial fluid becomes 

 increased in quantity, is thin and serous, and after a time 

 is seen to be mixed with the inflammatory exudation poured 

 into it. We then find that it has lost its clear appearance, 

 has become thick and muddy, and has floating in it flakes 

 of fibrin. 



If the case progresses favourably these materials are soon 

 absorbed and resolution occurs. In rarer cases the thicken- 

 ing and congestion of the membrane increases, and the 

 articular capsule becomes so distended with the increased 

 synovia and accumulated inflammatory discharges that a 

 kind of chemosis occurs. In other words, there oozes 

 through, without actual rupture of the membrane, a thin, 

 blood-stained, and purulent-looking discharge. 



It is an important point to note that in cases of synovitis 

 the fringes of the synovial membrane become swollen and 

 blood-injected, forming noticeable red elevations at the 

 margins of the cartilages. It is then that the diseased con- 

 dition soon spreads and runs into arthritis. 



Further, it is important, especially with regard to the 

 question of the degree of pain and lameness likely to be 

 caused, to note that often granulations are thrown out upon 

 the looser folds of the membrane. As these increase in 

 size they come to form fringed and villous membranous 

 projections inserting themselves between the bones forming 

 the articulation. In such cases there is no doubt that the 

 intense pain sometimes observed in these cases is due to 

 pinching of these prolongations of the synovial membrane 

 by the opposing bones of the joint. 



