ANIMAL DENTISTRY. 157 



bulum in the inferior arcades frequently points to the 

 surface of the jaw and constitutes the well known dental 

 fistula of the inferior maxilla. (See Fig. io8.) 



The incisor and canine teeth are not susceptible to the 

 condition. 



Diagnosis: — The molar tooth of the horse reaches the 

 advanced stage of decay unobserved in most instances, as 

 the incipient stages progress without clinical signs or 

 apparent discomfort to the animal. The fetid breath, fistula 

 or tumefaction of jaws or mouth usually create the first sus- 

 picion of decayed teeth. In the absence of these outward 

 signs they are only encountered accidentally in palpations 

 of the mouth during dental operations. The earliest diag- 

 nosis of a decayed molar is made when the infective inflam- 

 mation extends rapidly into the respiratory mucous mem- 

 brane, before any gross changes occur in the tooth. In 

 these cases the unilateral fetid nasal discharge leads to an 

 examination for abnormal (open) infundibula in one of the 

 superior molars. Anorexia, rejection of partially masti-. 

 cated food, dislike for cold water or turning the head to one 

 side while masticating, are occasional signs of decay in the 

 incipient stage, but the diagnosis must be confirmed by 

 better evidence. 



The relative decay of the teeth of horses will assist ma- 

 terially in locating the offending member. The fourth su- 

 perior molar, owing to its position in the center of the arcade 

 and its unstable neighbors during the second year of colt- 

 hood, is the most common seat of the disease. Out of a total 

 of two hundred decayed teeth observed, one hundred and 

 nineteen were fourth superior molars. The fifth superior, 

 the third superior and fourth inferior were next in order, 

 while the remainder were divided quite evenly among the 

 first superiors, the sixth superior and the remaining inferior 

 molars. The second superior was not found decayed until 



