584 THE EXTERIOR OF THE HORSE. 



makiog them narrower, or even in applying a tip. Bourgelat, from 

 purely theoretical considerations, had advised a method of shoeing 

 different from that in question. H. Bouley opposed them, and demon- 

 strated that they are not in accord with the facts of practice.^ 



D. — Defects existing Separately or Simultaneously in the 

 Anterior or the Posterior Members. 



1st. Rocking. — Rocking consists in a lateral balancing of the 

 body, comparable to the to-and-fro movements of a cradle, which is 

 apparent particularly in the trot or the walk. 



The horse can rock in front, behind, or in both extremities at the 

 same time. These lateral oscillations always consume a portion of the 

 force destined for propulsion, and, as Lecoq has said, the more ap- 

 parent they are the less the animal machine becomes adapted to the fast 

 gaits. 



This defect, sometimes due to weakness and exhaustion, is seen pref- 

 erably in horses having an excessive width of the chest, of the croup, 

 and of the base of support. It is observed, besides, in horses with 

 crooked legs and bovine knees. Finally, let us add that, according to 

 our observation, horses, at first very regular in their gait, will rock 

 themselves when their obesity becomes excessive ; conversely, we have 

 seen the defect disappear under the influence of emaciation. 



It can be understood, from the causes mentioned, that slow and 

 weakened animals may be affected with this balancing only temporarily, 

 for with age, moderate work, and sufficient nourishment they may 

 acquire the energy and strength which they lack. As to those whose 

 rocking is due to irregularities in the axes of the limbs, they can never 

 be corrected, and there exist no means of palliation. 



It is to be observed that certain trotters rock in the walk or the 

 slow trot, but show nothing abnormal when their gait acquires a greater 

 velocity. 



Rocking never takes place in the gallop, on account of the great 

 speed employed, the feebleness of the transverse displacements of the 

 centre of gravity, and the narrowness of the base of support. We 

 know that, in such cases, the imprints of the left members tend to 

 approach those of the opposite side, and we have even seen that the 

 trail in race-horses is represented only by a single line of imprints. 



This defect is therefore more or less grave according to the nature 

 of the work. 



1 For more details, see the excellent article by H. Bouley upon Jorging, in Nouveau Diction- 

 naire de m6decine, de chirurgie et d'hygi6ne v^t6riuaires, t. vii. p. 214. 



