STIFF JOINTS. 



271 



Stiff Joints and Knuckling Over. 



GENERAL REMAKKS. — I sliall confine my attention, under this 

 heading, to the joints of the fetlock and knee. 



All are aware of the tendency of the pastern, especially of 

 horses used at fast paces, to become unduly upriglit from the effects 

 of work. Examine the joint and this upright condition of the 

 pastern will be found to be owing to inability to extend the joint 



Fig. I02. — Alternate position assumed in rheumatoid arthritis of stifle. 



to a normal extent ; in other words, to bring the fetlock pad 

 sufficiently near the ground. As the action of a limb in producing 

 locomotion is due to the difference between its length when its 

 joints are bent and its length when they are straightened out ; 

 loss of ''play" in the fetlock joint (or uprightness of pastern) is 

 always followed by more or less loss of power of locomotion. In 

 light saddle-horses which are sound and have good action, the 

 fetlock pad, in the gallop or fast canter, should come nearly 

 down to the ground, as in Fig. 11 (p. 39), in which the pastern 

 makes an angle of about 120'^ with the cannon bone. The maxi- 

 mum direct flexion (bending) of a healthy fetlock joint is showij, 

 in Fig. 103. 



