n board ship, where no doubt pedal congestion takes place. And
perhaps some subjects start it in their marches in mobs down country
in Australia. Concussion may be the cause among older horses, but the
specimens photographed were taken from remounts, that had either done no
work or only very gentle work, in a deeply littered riding school.

[Illustration: FIG. 153.--EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]

'_Treatment_.--It is obvious from the position of this disease that
treatment will be of no avail in producing a cure. As already stated, the
disease is insidious and progressive, and it is hopeless to expect to
arrest the growths once they are started. Unnerving would no doubt remove
the symptom (lameness) of the disease, but an unnerved horse is not of much
good for army purposes. I therefore consider that once the disease becomes
firmly established it is an unfortunate and incurable one.

[Illustration: FIG. 154, 155--EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]

'Post-mortem reveals the small nodular growths on the inner surfaces of the
wings of the pedal bone, and if long established the ends of the navicular
bone are also involved. Exudation and gradual growth of false material
around the nodules takes place, which also serves to increase pressure.'[A]

[Footnote A: Captain L.M.Smith, A.V.D., _Veterinary Record_, vol. xi., p.
229.]

3. 'This case was brought for my opinion. The horse was lame, and walked
similar to one that had had laminitis, putting the heel down first upon
the ground. I ordered the patient to be destroyed. You will note the
ossification of the flexor pedis at its attachment to the pedal bone.
I enclose photos of the ground, also of the articular, surfaces of the
bone.'[A]

[Footnote A: F.B.Jones, M.R.C.V.S., _Veterinary Record_, vol. xi., p. 230.]

B. PYRAMIDAL DISEASE, BUTTRESS FOOT, OR LOW RINGBONE.

_Definition_.--A condition of periostitis and ostitis in the region of
the pyramidal process of the os pedis, usually preceded, but sometimes
followed, by fracture of the process, and characterized by deformity of the
hoof and an alteration in the normal angle of the joint.

_Causes_.--In the majority of cases buttress foot is brought about by
fracture of the pyramidal process. Thus, although distinct evidence of such
is nearly always wanting, we may assume that the original cause is violent
injury to the part in question. Properly, therefore, one would say that
this condition should be