340 DISEASES OF THE HORSE’S FOOT 
of great importance to the surgeon. It enables him when 
operating to distinguish with some degree of certainty 
those portions of the cartilage which are healthy and those 
which are not. 
(b) Necrosis of Tendon and of Ligament.—This complica- 
tion of quittor is, as we have said before, treated by other 
writers as a distinct form of the disease, and described by 
them under the heading of Tendinous Quittor. 
This simply means, of course, that the diseased process 
has extended to either of the flexor tendons, to the tendon 
of the extensor pedis, or, perhaps, to the ligaments of the 
pedal articulation. 
Of the flexor tendons, the perforans is the one commonly 
attacked, by reason, of course, of its more superficial 
position. At times, however, especially when its aponeu- 
rotic expansion is diseased, the necrosis of the perforans 
spreads until the aponeurosis is eaten through and the 
phalangeal sheath penetrated. Septic materials gain 
entrance thereto, and commence to multiply. In this way 
the flexor perforatus is invaded, and comes to share in the 
diseased process. 
The extensor pedis is usually attacked by extension of 
the disease from a necrotic cartilage, or results from the 
infliction of a severe tread in a hind-foot. In this case the 
diseased structure has nothing between it and the articula- 
tion, the synovial membrane in one position actually lining 
its inner face. The result is that a condition of synovitis 
is easily set up, and the case aggravated by that and by 
arthritis. 
With the flexor tendons attacked pain is always very 
great, and lameness is exceseive. This, however, is not 
sufficiently characteristic to enable us to determine the 
precise seat of the necrotic changes. Later, however, a 
tender but hard enlargement made its appearance in the 
hollow of the heel, which enlargement, later still, became 
soft and fluctuating. At this stage there is also consider- 
able swelling along the whole course of the tendons, as 
high up as the knee or the hock. The foot is carried 
