DIAGNOSTIC PRINCIPLES 51 



porting member. To augment the manifestation of certain af- 

 fections, it is necessary to cause the patient to walk backward, 

 and each one of these tests of locomotion serves to point out 

 in a more or less characteristic manner, the site of the affection 

 which is causing lameness in different cases. 



Sprains or injuries of lateral ligaments of the extremities, 

 ringbone and certain foot aft'ections, are made manifest by a 

 side to side movement or a pivotal movement. In fact, wherever 

 it is possiI)le to cause undue or unusual tension to be exerted 

 upon an inflamed structure, manifestation of pain is the re- 

 sponse. In an inflamed condition of the lateral side of the pha- 

 langes, unequal weight-bearing such as a rough road surface will, 

 by virtue of the leverage which the solar surface of the foot af- 

 fords, cause undue strain upon such inflamed parts, and in- 

 creased lameness is evident. 



When an animal is made to travel in a circle, when a mem- 

 ber affected with supporting-leg-lameness is on the inner side 

 of the circle, lameness is accentuated because weight is borne by 

 the lame leg for a greater length of time, the result of such cir- 

 cuitous manner of locomotion. In swinging-leg-lameness, on 

 the other hand, because pain is increased at the time an affected 

 member is being advanced, lameness is increased when the sub- 

 ject is made to travel in a circle, with the lame leg on the out- 

 side of a circle thus described. 



In supporting-leg-lameness, the transientness of the w^eight- 

 bearing period upon the affected member is the determining 

 factor in the production of lameness. This unequal period of 

 weight-bearing upon the front legs, for instance, causes an ac- 

 celeration in the advancement of the sound member, in order to 

 relieve the diseased one which is bearing weight. In other words, 

 when an animal that is affected with supporting-leg-lameness 

 travels in a straight line, since weight is borne by the diseased 

 leg for an abnormally short period of time, the sound member 

 needs be in the act of advancement a correspondingly short pe- 

 riod. The result is then, an une(iual division of stride; a nod- 

 ding of the head with the catching up of weight by the sound 

 leg, — in front leg affections — and this is termed limping. 



With continuous exertion as in travel for a considerable dis- 



