838 CAUSES OF INFLAMMATION OF THE FLEXOR TENDONS. 



suffer most. The greater the muscular development of the hind- 

 quarters, the greater the shocks produced in the fore limbs by the 

 violence with which the weight of the body is thrown forward on 

 to them. Spirited animals suffer more than phlegmatic. For 

 similar reasons, cart-horses show strain frequently in the hind limbs. 

 Those which work in two-wheeled carts and have oblique pasterns 

 are specially liable to tendon strain of the hind limbs, particularly 

 when descending hills with heavy loads. 



Strains of flexor tendons are produced by the body-weight 

 suddenly falling on the front limbs when the horse is jumped or 

 quickly pulled up (passive strains), or by continued violent action 

 of the flexor muscles (active strains). In the first instance, the 

 flexor perforatus is principally involved, its less length causing it 

 to suffer first from forced dorsal flexion of the phalanx. The flexor 

 perforans is less likely to be injured. The effective length must 

 be reckoned as the distance between the lower insertion and the 

 upper one, and in the perforans and perforatus tendons from the 

 upper insertion of their so-called check ligaments. 



Tendinitis produced by excessive muscular action (active sprain) 

 has, with few exceptions, its seat in the flexor perforans, because 

 the muscular head of this tendon is by far the stronger, and its tendon 

 is therefore exposed to the greater strain. But passive strains also 

 occur, as shown by the frequence with which the check ligament, 

 which extends to opposite the middle of the metacarpus, becomes 

 inflamed. With regard to strain of the check ligament, which is 

 particularly common in cart-horses, the remarks made re strain 

 of the suspensory ligament in large measure apply. The conditions, 

 however, are not precisely the same, because owing to their respective 

 mechanical arrangements strains do not affect the suspensory and 

 check ligaments in exactly the same way. Judging from their course 

 and attachments, it would appear that while the suspensory 

 ligament is always more or less in tension, the check ligament is 

 frequently entirely relaxed, and that stress, when thrown on it, is 

 liable to be of the nature of a sharp jerk. Such a jerk would follow 

 any miscalculation of distance on the horse's part, as for instance 

 when the animal unexpectedly steps into a hole. Heavy work is 

 another well-recognised cause of strain of the check ligament in 

 cart-horses. In this case the injury is probably inflicted in starting 

 the load. The animal leans forward in the collar, and before actually 

 commencing to pull causes excessive flexion of the fetlock. At 

 this moment the perforans muscle being relaxed a heavy strain is 

 thrown on the check ligament, which may be injured. Closely 



