DEFECTS IN THE GAITS. 591 



the judicious remark of H. Bouley, the nodding of the head, characteristic of lame- 

 ness, takes place upon the side of the lame member in posterior lameness, while 

 in anterior lameness this is the reverse. 



The croup, like the head, also shows an unequal movement of equilibrium 

 under the influence of the unequal action of the lame member ; but, less marked 

 than that of the head, it furnishes a less certain index. It consists ordinarily of 

 an exaggerated lowering of this region at the moment when the healthy member, 

 upon which the body takes its principal point of support, touches the ground, 

 while it is almost imperceptible when the diseased member touches the ground. 



An error rather frequent among laymen consists in believing that the animal 

 is lame in the foot upon which he falls. This results from a false interpretation 

 of the objective phenomena, which are so well known to practitioners that it is 

 not necessary to give the proof of its illogical foundation ; we merely mention it 

 here because the veterinarian has frequently to argue this idea out of his client's 

 mind. 



3d. Lameness in Two Members. — There are cases in which the horse is lame 

 in two members at one time, — in the anterior, the posterior, the lateral, or the 

 diagonal biped. 



" The symptoms proper to a lameness of the anterior or the posterior biped 

 give rise to an irregularity or an impediment of action in general as intense in 

 the right as in the left member. The movements of the biped are modified to 

 the same degree on both sides, making thus a contrast with those of the other 

 biped, which acts normally. 



" As to lamenesses of the lateral bipeds they are characterized by the com- 

 bined symptoms of anterior and posterior lameness, but much more increased 

 on account of the greater difficulty of progression. 



" Let us suppose, for example, a horse lame in the right diagonal biped ; at 

 each step the nodding of the head and the lowering of the croup will be very 

 decided at the moment when the left diagonal pair touches the soil. 



" At first sight there is a want of harmony in the movements which is not 

 easily explained, but by directing one's attention exclusively to the anterior 

 biped on the one part and the posterior on the other, the double cause which 

 produces it is soon discerned. 



" The irregularity in the progressive movements is still more decided when 

 the animal is lame in a lateral biped. In this instance it is difl[icult for him to 

 move in a straight line ; if he limps on the left, for example, the centre of gravity 

 being displaced upon the right, the body of the animal will be carried in this 

 direction, and progression will be affected on that side.'" 



4th. Lameness in Four Members. — The irregularity of the locomotory func- 

 tion, here, is such that the lameness is very apparent to the eyes of the least 

 experienced persons. It is therefore useless to dwell further on this point. 



We must discuss two points more : the duration and the type of the 

 lameness. 



In relation to the first factor, a lameness is acute, recent, or chronic. 

 This can be established from the history of the lame animal, and a 



' H. Boulev, loc. cit. 



