370 DISEASES OF THE HORSE’S FOOT 
saying that, some several years ago, the Council of the 
Royal College of Veterinary Surgeons, at the request of the 
Royal Commission on Horse Breeding, drew up a list of 
those diseases ‘which by heredity rendered stallions so 
affected unfit as breeding sires,’ and that in that list was 
included side-bone. 
Side-bones, therefore, are hereditary. We think, how- 
ever, the statement needs qualifying. It is in this way: 
side-bones occur only at a certain, usually well-defined, time 
after birth, and we might say are never congenital. They 
occur only after the animal has been put to work, and are 
more or less plainly due to mechanical causes—namely, the 
ill effects of shoeing and concussion. The cause of their 
appearance, in short, is more plainly extrinsic than intrinsic, 
and side-bone in the horse is, as Professor McCall puts it, 
about as much due to heredity as is corn on the human foot. 
Between these two opinions—that they are plainly 
hereditary, and that they just as plainly are not-—it is well 
to strike a middle course. They are, we will say, heredi- 
tary in this way: So long as a cart animal is bred, to put it 
vulgarly, ‘top-heavy’ (that is, with a body out of reason- 
able proportion to the feet that have it to support), so long 
will the foot be subjected to a greater concussion, and so 
long will side-bones in such animals commence to make 
their appearance at about middle life. 
In addition to the causes we have now mentioned, side- 
bones are often the result of other diseases of the foot. 
They thus occur as a sequel to sub-horny quittor, to sup- 
purating corn, to complicated quarter sand-crack, or to the 
inflammation of the parts occasioned bya prick. They also 
arise in many instances from the effect of a prick or injury to 
the coronet. Among the latter we may mention treads from 
other animals, and treads inflicted by the animal himself 
with the calkin of an opposite shoe, or the repeated injury 
occasioned by the shafts being carelessly allowed to drop on 
to the foot. In severe cases of laminitis, too, the cartilages 
are nearly always affected. In this instance the inflamma- 
tory phenomena in the os pedis no doubt give rise to an 
