46 Williams, Fisher, and Udall: The Spavin Group. 
limited they may not interfere greatly with the animal’s move- 
ments, but when extensive, render its movements stiff and inter- 
fere with lying down and getting up. 
Fractures may occur either in what we may term a spon- 
taneous manner, that is, in the course of ordinary movement, or 
function, or accidentally from some extra insult. 
We have already referred to the thirteen broken ribs shown 
in Fig. XVII, in which the fractures were scattered irregularly 
over both sides of the chest and had apparently occurred singly 
and without any violence. The spine is liable to become so 
fragile as to fracture spontaneously in getting up, and the 
pasterns and navicular bones occasionally give way in a similar 
manner without adequate violence; the admirably protected 
pedal bone may give way on its plantar surface, permitting the 
tendon of the flexor pedis to pull out, carrying a portion of the 
bone with it. While this may occur in any case, it is, especially 
prone to follow neurotomy with the. consequent weight put 
upon the pedal bone which in its pathologic state it is unable to 
bear. 
The “accidental” fractures occur variously, by falls or 
blows like other fractures, only more certainly induced usder 
slight provocation. 
Of greatest interest to us are the fractures from casting for 
operation. A large proportion of animals suffering from frac- 
tures during casting accompany confinement for some surgical 
operation for spavin, ringbone, navicular disease, or some other 
member of the group. The fact is significant and we habitually 
decline to cast a colt for castration except definitely at the owner’s 
risk when the presence of exostoses referable to this group are 
evident. We regard the casting of these animals as a constant 
danger quite out of proportion to ordinary casting risks and 
when necessary to confine such a patient for any reason, are 
careful to stipulate that it is done specifically at the owner’s risk 
after he has been fully advised of the dangers. 
PROGNOSIS. 
The prognosis of the disease has been largely covered inci- 
dentally in the preceding section. 
The probability of life is excellent, the fatalities occurring 
almost only in severe cases of the maladies or forms known as 
osteo-porosis and rickets. 
