284 PARTICULAR LAMENESSES. 



the lameness is characterised by, on the part of the animal, 

 inability to flex it, by heat, swelling, pain on pressure, and 

 more or less pointing of the foot. 



SESAMOIDITIS. — INFLAMMATION OF THE SESAMOID BURSA. 



The posterior part of the sesamoid bones is covered by carti- 

 lage, forming a groove, over which the flexor perforans plays. 

 Both the cartilaginous pad and the tendon are liable to injury, 

 which causes severe and obstinate lameness. 



Sesamoiditis may also arise from an injury to the inferior part 

 of the suspensory ligament — whether involving it above the 

 bifurcation or confined to one branch only — by extension of the 

 inflammation ; and is oftener met with in hunters than in any 

 other class of horses. 



Sesamoiditis is not so often found in the fore as in the hind 

 extremity, and is rather difficult to diagnose, owing to the 

 accompanying swelling being very limited in extent. 



The pathology is as follows : — 



1st. Inflammation of the bursa, owing to sprain or other 

 injury. 



2d. Increased secretion into the sjoiovial cavity, causing a 

 bulging of its capsule upon either side of the flexor tendon. 



3d. Ulceration of the cartilage of incrustation, softening and 

 laceration of the fibres of the tendon, and, finally, adhesion 

 between the bones and tendon, 



4:th. When arising from sprain of the suspensory ligament 

 there will be thickening of the ligament or of one of its branches, 

 associated with that loss of cohesion in its structure which seems 

 so characteristic of inflamed ligament, as manifested by the 

 animal going upon the heel, and descent of the fetlock pad. 



Symptoms. — Lameness, the horse, unless the suspensory liga- 

 ment be involved, going on his toe; heat at the back of 

 the fetlock, with swelling of the bursa. This swelling is diffe- 

 rent in its character from a mere dropsy of the fetlock joint or 

 sheaths of the tendons ; in sesamoiditis, although it fluctuates 

 upon pressure, it feels tense, the capsule being fully distended 

 with fluid; whereas in a common wind -gall it is soft, and easily 

 pressed from one side of the leg to the other. This difference 

 in the character of the two enlargements must be remembered. 



