338 DISEASES OF THE HORSE’S FOOT 
probing is seen to lead direct to the position in which we 
know the cartilage to be, we know of no precise means by 
which the existence of this condition may be diagnosed. 
When free from other complications, the horse with his 
foot in this state may travel fairly sound. This is so when 
the necrosis is situate in the posterior half of the cartilage, 
in which case the irritation set up by the disease is confined 
to the comparatively non-sensitive tissues of the cartilage 
itself and the fibrous mass of the plantar cushion. When 
attacking the anterior half of the cartilage, the close con- 
tiguity of the joint renders the disease of a more serious 
nature. It is then that we have acute pain, and with it 
extreme lameness, for in this position it is more than likely 
that we have involved either the synovial membrane of the 
articulation or the tops of the sensitive lamine. It will be 
remembered that here the synovial membrane protrudes as 
a small sac between the antero- and postero-lateral liga- 
ments of the joint. More or less easily then it is bound to 
come into intimate contact with the septic matter attending 
the necrosis of the cartilage, and so share in the inflam- 
matory processes, afterwards communicating them to the 
interior of the articulation. 
With necrosis of the lateral cartilage is always swelling 
and thickening of the skin and subcutaneous structures of 
the coronet. This is the greater the longer the disease has 
been in existence. Upon the swelling is seen the mouth of 
the fistula, or it may be the mouths of several, and from 
them all a discharge of pus. 
The mouth of each fistula is generally filled with a 
mulberry-like granulation tissue, standing above the level 
of the skin, and bleeding easily if touched. The exuding 
pus is thin and pale gray in appearance, gritty to the 
touch, and generally free from pronounced smell. At 
other times its colour is reddened with contained blood, 
and floating in it are tiny particles of a pale-green sub- 
stance, which when picked up and rubbed between the 
fingers are seen to be small fragments of the diseased 
cartilage. 
