SYNOVIAL DISTENSIONS. 819 



tendon sheaths or wrenching of joints. The synovial membrane 

 becomes inflamed or blood is poured into its cavity. In exceptional 

 cases, external influences, like displacement or contusion of the joint, 

 occasion enlargements of bursal cavities. Thus, bruising may be 

 followed by bleeding into the capsule of the joint or tendon sheath, 

 and years after the accident, flakes of fibrin may be found in the 

 joint or tendon sheath. - 



Symptoms. The symptoms need scarcely be enumerated after 

 what has gone before ; and if the anatomy of the parts is borne in 

 mind, diagnosis presents no difficulty. Bursal enlargements, both 

 of the knee- and fetlock- joints, diminish, however, when the limb 

 is relieved of weight or is flexed, whilst those of tendon sheaths 

 become more distinct and appear more tensely filled. Swellings 

 due to distension of articular sacs are generally horizontal, those of 

 tendon sheaths more or less vertical. The presence of acute 

 inflammation is shown by heat, swelling, and lameness. 



Prognosis and course. Chronic dropsy of the synovial cavities 

 of joints and tendons results in the horse from chronic irritation ; 

 in occasional instances from acute inflammation ; bursitis of the 

 sheaths of the extensor tendons is generally accompanied by lame- 

 ness. Enlargements of the upper sheath of the extensor suffraginis 

 often contain fibrinous clots — -a result of their hemorrhagic origin — 

 even after having been in existence for some time. On the other hand, 

 enlargements developing either from joints or from flexor tendon 

 sheaths are, with few exceptions, due to chronic irritation of the 

 synovial membrane. Sometimes the cavity is filled with light- 

 coloured, clear serum ; less frequently it contains small bodies 

 resembling grains of rice ; occasionally the tendon sheath is more 

 or less thickened (tendovaginitis chonica fibrosa ; indurated galls). 

 In such case the tendon may be involved. 



For the most part, such enlargements in horses are only regarded 

 as blemishes, and in old animals are seldom entirely absent. When 

 of fresh growth and small size, they may, if properly treated, be 

 cured ; but, on the other hand, may persist for long, and resist all 

 forms of treatment, yet without impairing the animal's usefulness. 



Distensions of the extensor sheaths may cause lameness, but 

 are more accessible to operative interference, and are, therefore, 

 of less moment than flexor distensions. Chronic distension of flexor 

 sheaths, especially when near joints, is more difficult to remove, 

 still more so are distensions of capsular ligaments. 



Galls on the flexor tendons, particularly in the hind limbs, are 

 apt to become chronic and indurated. They are even more trouble- 



