228 DISEASES OF THE JOINTS. 



distends whole joints or bursse. There is seldom much pain 

 or lameness, because the ligamentous and other textures have 

 been yielding gradually, and are but passively distended by the 

 fluid. The quantity of the secretion is liable to variations, dis- 

 appearing more or less upon exercise, and accumulating after a 

 short rest. During long periods of rest, however, the accumula- 

 tions may disappear, and appear again when the animal is put 

 to work. 



Young growing cart-horses are very subject to the formation of 

 these fluid enlargements, more especially about the hocks. Wlien 

 they are full grown, however, their joints may become quite fine. 



The treatment most appropriate is the application of blisters 

 and pressure ; but this will be again referred to under the head 

 of Lameness. 



ANCHYLOSIS, OR THE STIFFENING OF THE JOINTS. 



There are several forms of anchylosis : — 1st. Osseous, or true ; 

 2d. Fibrous ; 3d. Ligamentous ; 4:th. Spurious. 



1st. The true anchylosis may be general and complete at every 

 part of the joint, as in some bone-spavins and true ring-bones, 

 where all trace of the articulation has been lost, and the opposing 

 bones so firmly united as to appear as one bone. Before 

 this can happen, the articular cartilages and laminal layers of 

 the opposing bones must be removed by an ulcerative absorp- 

 tion, and an exudate thrown out from their cancellated structure ; 

 which, becoming organized into bony matter, cements the bones 

 together. This is the natural termination and cure of such 

 causes of lameness, and it is usually accompanied by a deposition 

 of bone upon the outside of the affected joint, which aids in the 

 completion of the anchylosis. 



2d. The fibrous. — The opposing surface of the bones may be 

 united by fibrous tissue. As a rule, however, this is only found 

 during the earlier stages of true anchylosis. 



3d. The ligaments become rigid to such an extent as to make 

 a joint more or less stiff and immoveable, whilst the articular 

 surfaces of the bones remain healtliy. Stiff joints of old horses 

 are examples of this. 



^th. The spurious is that which depends on deposition in tex- 

 tures external to the joint, uniting the various structures to each 



