246 VETERINARY STUDIES 



Synovial sacs. — The ordinary wind puffs, bog spavins, and 

 thoroughpins are typical illustrations of enlarged synovial sacs. 

 They are not usually the cause of lameness and are to be re- 

 garded rather as blemishes and indications. They are common 

 in overgrown draft colts that have not had sufficient exercise. 



Wind puffs are found just above the ankles and in mature 

 horses usually indicate too much hard work. 



Bog spavins are enlargements of the synovial sac of the hock 

 joint, and appear on the inner and front part of the hock. They 

 are often hereditary. 



Thoroughpins are similar to bog spavins and wind puffs, ex- 

 cept in location. Thoroughpins appear at the upper and back 

 part of the hock. They may or may not connect with the syno- 

 vial sac of the hock joint. 



Open joint is usually the result of puncture of the synovial 

 sac and the entrance of bacteria, which cause an acute inflam- 

 mation, known as synovitis. This form of lameness can usually 

 be very easily detected, and the cause recognized. It is very 

 serious under all circumstances, and frequently results in death. 

 The veterinarian should be called at once. 



Hygromas. — These are enlargements of serous sacs at promi- 

 nent points and due to injury. They are found at the elbow, 

 knee, external angle of ilium, point of the hock, "pin bone," 

 point of shoulder, etc. They sometimes have thick, hard walls. 

 A common example is found at the knees of stabled cows. 



Miscellaneous. — Corns usually appear at the inner heel of the 

 front foot — in the angle between the bar and wall. They may 

 be caused by bruise of the sole but more commonly by lateral 

 pressure of the weight from above upon the sensitive lamina? 

 and velvety tissue in a contracted heel. 



They appear as bruised areas under the sole at the point 

 mentioned. The wall at the affected heel is apt to show ridges 

 which are not parallel with the coronary band. A horse with 

 a corn frequently "points" as in a case of navicular disease. 



In case the bruised area becomes infected, pus forms and 

 eventually discharges at the coronary band. The case is then 

 known as a "quittor." 



Navicular disease is a slowly developing, chronic affection of 

 the navicular articulation. The navicular bone, with its articu- 

 lar cartilage, the deep flexor tendon, and synovial membrane 

 at that point may be involved in the inflammation and its re- 



