38 
DISEASES OF THE TOOTH PROPER. 
described this condition in a thirty-year old horse as periodontitis. Only 
exceptionally in middle-aged horses are the molars worn down to the 
root and mastication impeded. Cases occurring in early life are usually 
serious. They clearly result from individual idiosyncrasy, consisting in 
defective hardness of the enamel and dentine. The only useful treat¬ 
ment consists in giving soft and crushed food to assist mastication and 
prolong the workable period. 
(f) the smooth mouth. 
Enamel and dentine being of unequal hardness, the latter wears away 
more rapidly and produces the roughened fold-like appearance on the 
grinding surface of the molar, requisite for effectively triturating the food. 
But when enamel and dentine wear at the same rate the surface becomes 
even and polished. In advanced age this normally occurs, because in 
the deeper portions of the tooth the enamel ceases. It also occasionally 
occurs in young animals on account of insufficient hardness and dura¬ 
bility of the enamel, and is more serious than in older horses. The 
smooth mouth during mastication resembles an uncut millstone during 
grinding. Mastication is of course less impeded when single teeth are 
affected than when the condition is general. 
Treatment is confined to palliatives, giving crushed or ground grain, 
gruel, or bran mashes, and allowing longer time for feeding. 
The opposite condition in horses is termed “ ruminant’s mouth.” The 
grinding faces become exceedingly uneven. This is normal, however, so 
long as the molars have not come into wear; but it rarely persists, and 
is seldom troublesome. 
(C) DISEASES OF THE TOOTH PBOPER. 
(a) dental caries (caries dentium). 
The term “ Caries ” is used to describe the process which results in the 
gradual destruction of the cement and dentine of the teeth, the enamel 
remaining comparatively intact. In veterinary surgery this term is often 
erroneously used to describe alveolar periostitis. At one time Moller 
was doubtful whether caries occurred in animals, but Kitt’s observations 
and his own later experience show that this opinion was not strictly 
conect, and he has lately reported some cases of undoubted caries in the 
molars of horses. Kitt has pointed out that in animals it takes the form 
of diy chiomc canes, and Baume has noted the same fact in connection 
with ruminants and dogs. He states that the process starts either in the 
cement of the enamel folds, or in the centre of an “ island ” of dentine. 
Stockfleth and Kitt believe that caries starts in the remains of the 
