AN ESSAY ON CHRONIC PODOTROCHOL1TIS. 
531 
sequently, to redouble their action from the moment that the 
power of any one extremity, and especially of a fore limb, has 
become diminished, or totally paralyzed, no matter what the cause 
be. The ** nodding of the head,” as this movement is vulgarly 
called, has no other signification than that of a displacement of the 
centre of gravity : according to the laws of mechanics, the lever 
throws the weight backwards, in order to exempt the sound leg 
from it, and render it fitted for progression. Animals instinctively 
spare the suffering organ. All this is lost sight of by those who 
regard nodding flexions of the head as indications of pain in the 
levator humeri muscle. 
But I should be diverging too widely from my subject were I to 
enter into a critical review of all the symptomatology of shoulder- 
lameness : they who will take the pains to compare together the 
various authors who have treated of it, will soon convince them- 
selves that this part of the pathology of this disease is a perfect 
chaos enveloped in thick darkness. The most flagrant contradic- 
tions occur at every step ; and these have become imperceptibly 
ranked, per fas et nefas, among the characteristic signs of the 
disorder ; and, on account of the value accorded to them, appear to 
have acquired a certain prescriptive right. The phrase “going wide,” 
generally applied to lamenesses of the shoulder, may have had a 
large share in producing this : different affections have been com- 
prised under one generic denomination; phenomena strange to them, 
or which they only have in common with other diseases, have been 
attributed to them as pathognomonical characteristics. The in- 
difference and carelessness with which the examination of these 
doubtful cases have too often been conducted must inevitably lead 
to similar errors. 
When a lame horse is brought to a veterinary surgeon, he does 
not, until he has made a manual examination, draw any conclusion 
from the positive symptoms furnished by the altered action of the 
animal ; he does not at once set down the lameness to the score of 
shoulder-shotten. If, after carefully examining the whole limb, he 
is unable elsewhere to detect any indications that will guide him 
to the seat of disease, he unites these negative symptoms, and they 
appear to him sufficient to diagnosticate a shoulder-lameness. He 
has the horse trotted once more, and cheats himself into the belief 
that the abnormal action of the limb leaves no doubt as to the 
existence of disease in the shoulder. He compresses and pinches 
the shoulder, and, unless the animal stands as motionless as a post, 
the verdict is pronounced : the unfortunate shoulder is condemned, 
notwithstanding its innocence, because no accusation can be brought 
against any other part. 
In such a mode of proceeding it cannot be wondered at that 
