THECOCENTESIS * 57 



to hard work, fast work or constant work, appearing often 

 soon after the young animal is first submitted to exertion. 

 They generally advance gradually, but in rare instances sup- 

 ervene a sudden injury. They usually enlarge with work 

 and diminish with rest, but sometimes maintain a definite 

 size without change in character or dimensions. 



Pathologically, a wind-puff is a slight inflammation of the 

 synovial membrane of the entire sesamoidean sheath, to- 

 gether with a dilatation of its uppermost cul-de-sac. If the 

 inflammation is more intense, it may cause lameness during 

 the acute stage, but since the great majority of cases evolve 

 slowly without any initial period of acuteness, lameness is 

 scarcely ever observed. They vary in size from small, almost 

 imperceptible, fluctuant elevations to large elongated en- 

 largements that greatly disfigure the leg. They are always 

 harder and somewhat larger while the leg is supporting 

 weight. 



In an examination for soundness wind-puffs should be re- 

 garded as an unsoundness, in spite of the fact that they sel- 

 dom ever depreciate the utility of the patient. Their ten- 

 dency to enlarge, although small at the time of examination, 

 and their location on a conspicuous part of the leg, stamps 

 them as redoubtable blemishes. 



Thoroughpin is a distention of the tarsal sheath which 

 over-laps the posterior surface of the hock about six inches 

 superiorly, and as far as the middle third of the metatarsus 

 inferiorly. Inferiorly it is bounded by unyielding structures 

 that prevent any extensive distention, bpt superiorly the 

 space between the tendo-Achilles and the flexor pedis per- 

 forans, which is enclosed laterally only by the elastic skin, 

 facilitates the development of an almost unrestricted dilata- 

 tion. 



Like the wind-puff, thoroughpin generally, evolves under 

 the influence of a s-light, chronic inflammation of the synovial 

 membrane. The resulting excessive secretion and the con- 

 stant strain to which the part is subjected, gradually enlarge 

 the sac until it becomes a visible, fluctuant enlargement, 

 which can be pressed from side to side beneath the tendo- 

 Achilles. At first it appears only as a slight, flattened, very 

 soft enlargement externally, and then later shows itself also 

 on the internal aspect of the region. Rare cases, especially 

 those resulting from a single, sudden strain, may appear first 

 on the internal side. In either case the finality is the develop- 

 ment of a large, tuberous, fluctuating distention that is much 

 larger internally than externally. The enlargement may as- 



