318 
A. A. HOLCOMBE. 
If the inflammation is long continued, and especially if the animal 
is made to work, the deeper layer of the periosteum may become in¬ 
volved; in this instance there is superficial inflammation of the bone 
substance, and the products of the inflammatory action is thrown out 
upon the surface of the bone, detaching the periosteum, and by cutting 
off nutrition, induces a limited caries. The consequent suppuration 
still further separates and destroys the periosteum until this membrane 
is ruptured, and the pus is discharged through the cleft in the horn. 
SYMPTOMS AND COURSE. 
Since quarter-crack is seen in all classes of horses, although it is 
perhaps most commonly met with in those used for fast work, the com¬ 
plication above spoken of may also be seen in all classes—but not so 
with toe-crack, for it is of rare occurrence, except in animals of the 
heavier breeds, and used for slow and heavy work. Again, while toe- 
crack will be seen on the hind feet as well as the fore ones, quarter- 
crack seldom or never occurs behind. The presence of periostitis 
where either toe or quarter crack exists, will be detected by the charac¬ 
ter of the lameness, the soreness evinced upon pressure to the parts, and 
by the suppuration. Where permanent lameness accompanies either of 
these injuries to the wall of the foot, I very much doubt if it is ever due 
to any cause other than periostitis. In quarter-crack with periostitis, 
the foot is rested at every opportunity, and e,very step is accompanied 
with lameness. There is more or less heat around the coronet upon the 
inner side, while pressure upon the edges of the wound causes flinching, 
and tapping the wall with a hammer causes extreme pain. 
Regarding the suppuration, it may exist to a very limited extent, 
even without any periostitis whatever; but in these cases the lameness 
is entirely absent, or at most shows itself slightly while the animal is 
working, and subsides with a little rest. Where the inflammation of the 
periosteum has ended in suppuration, the quantity discharged is more 
or less extensive and continued, while if caries exists the peculiar smell 
of diseased bone will indicate its presence. 
The tendency in the majority of these cases of periostitis, if left to 
themselves, is always to caries, and, as a consequence, demands the in¬ 
terference of the surgeon. If, on the other hand, the patient is given 
rest, and foreign substances prevented from entering the wound, the in¬ 
flammation will subside, the suppuration cease, and the wound heal, 
providing it is placed in a favorable condition. 
The caries accompanying these two diseased conditions is never ex¬ 
tensive, exists more often in toe-crack, and is very amenable to treatment. 
