INFLAMMATION OF THE FLEXOR TENDONS. 837 



Rupture of the extensor tendons is very rare, and is usually 

 brought about by efforts to liberate a foot which has been caught 

 in some obstacle like railway points, or by a direct mechanical injury 

 severing the tendon. Healing is slow, owing to the excessive volar 

 or plantar flexion (" knuckling ") which occurs. A suitable iron 

 splint may, however, overcome the difficulty. 



IV.— INFLAMMATION OF THE FLEXOR TENDONS (TENDINITIS) 

 AND OF THE SUSPENSORY AND CHECK LIGAMENTS. 



Inflammation of the flexor tendons is very frequent in the horse, 

 and generally occurs in the fore limbs, on account of their being 

 much more exposed to the violent strains which form the general 

 cause of the disease. 



Causes. Horses with weak flexor tendons, heavy bodies and 

 powerful muscles, are most predisposed to tendinitis. The structure 

 of the tendon, or its power of resisting strain, is of the greatest im- 

 portance ; its absolute thickness bears no direct proportion to its 

 strength. On the contrary, tendons of considerable size and 

 surrounded by abundant paratendineum suffer more frequently 

 than the more sharply defined or those which are firm to the touch. 

 As mentioned under " Rupture of the Flexor Tendons," continued 

 rest seems to lower the resistance against strains. Rupture and 

 inflammation following severe diseases, are, in part at least, to be 

 referred to this fact. Further, all conditions which increase the 

 load on the limb and the strain on the flexor tendons favour 

 tendinitis. 



Long, weak, and slender pasterns are especially liable to it. The 

 strain on the tendons is increased by increased length and obliquity 

 of the pasterns. The more slender the fetlock-joint appears when 

 viewed from the side, the greater the mechanical disadvantage to 

 which the tendons are placed. For a similar reason, horses with 

 " tied-in " knees are disposed to tendinitis, this formation beino- 

 generally accompanied with small size of the fetlock. Further, 

 everything which favours dorsal flexion of the joint increases risk 

 of inflammation of the flexor tendons. Low heels and lono- toes 

 are therefore apt to cause it. Long toes throw a powerful strain 

 on the flexor tendons during the latter phase of movement, just 

 before the foot is lifted from the ground. The kind of work required 

 of the horse is also important. Thus race-horses and hunters, and 

 horses required to trot at a sharp pace for long periods, are the most 

 general sufferers. Animals with considerable powers of endurance 



