DISEASES OF HORSES 211 



but comprehensively expressed by the terms health and soundness. 



But let some change, though slight and obscure, occur among 

 the elements of the case ; some invisible agency of evil intrude among 

 the harmonizing processes going forward; any disorder occur in the 

 relations of co-operating parts; anything appear to neutralize the 

 efficiency of vitalizing forces ; any disability of a limb to accept and 

 to throw back upon its mate the portion of the weight which belongs 

 to it to sustain present itself, whether as the effect of traumatic 

 accidents or otherwise ; in short, let anything develop which tends to 

 defeat the purpose of nature in organizing the locomotive apparatus, 

 at once we are confronted by that which may be looked upon as a 

 cause of lameness. 



Not the least of the facts which it is important to remember is 

 that it is not sufficient to look for the manifestation of an existing dis- 

 cordance in the action of the affected limb alone, but that it is shared 

 by the sound one, and must be searched for in that as well as the halt- 

 ing member, if the hazard of an error is to be avoided. The mode of 

 action of the leg which is the seat of the lameness will vary greatly 

 from that which it exhibited when in a healthy condition, and the 

 sound leg will also offer important modifications in the same three 

 particulars before alluded to, to wit, that of resting on the ground, 

 that of its elevation and forward motion, and that of striking the 

 ground again when the full action of stepping is accomplished. Ina- 

 bility in the lame leg to sustain weight will imply excessive exertion 

 by the sound one, and lack of facility or disposition to rest the lame 

 member on the ground will necessitate a longer continuance of that 

 action on the sound side. Changes in the act of elevating the leg, or 

 of carrying it forward, or in both, will present entirely opposite con- 

 ditions between the two. The lame member will be elevated rapidly, 

 moved carefully forward, and returned to the ground with caution 

 and hesitancy, and the contact with the earth will be effected as 

 lightly as possible, while the sound limb will rest longer on the 

 ground, move boldly and rapidly forward, and strike the ground 

 promptly and forcibly. All this is due to the fact that the sound 

 member carries more than its normal, healthy share of the weight of 

 the body, a share which may be in excess from 1 to 250 pounds, and 

 thus bring its burden to a figure varying from 251 to 500 pounds, all 

 depending upon the degree of the existing lameness, whether it is 

 simply a slight tenderness or soreness, or whether the trouble has 

 reached a stage which compels the patient to the awkwardness of 

 traveling on three legs. 



That all this is not mere theory, but rests on a foundation of 

 fact may be established by observing the manifestations attending a 

 single alteration in the balancing of the body. In health the support 

 and equilibrium of that mass of the body which is borne by the fore 

 legs is equalized, and passes by regular alternations from the right to 

 the left side and vice versa. But if the left leg, becoming disabled, 

 relieves itself by leaning, as it were, on the right, the latter becomes, 

 consequently, practically heavier, and the mass of the body will in- 

 cline or settle upon that side. Lameness of the left side ; therefore, 



