510 DISEASES AND INJURIES OF THE FACIAL REGION. 



of secondary dentine, by the surface of the pnlp under the ex- 

 citement of caries in the contiguous tissue. 



Symptoms of caries of the teeth are those of pain. The horse 

 so suffering will, whilst eating, suddenly stop masticating his 

 food, perhaps drop it from his mouth, will rest his cheek on the 

 manger, holding his head to one side, and after a time, when the 

 pain subsides, will begin to feed again ; or he may " quid " his 

 food, throwing out large boluses mixed with much saliva. I 

 have seen instances where the mansjer would be half filled in 

 the morning with semi-masticated food and sour salivary 

 secretions. 



Caries of the fang will usually be denoted by an enlargement 

 on the bone which contains it, corresponding to its position; 

 this enlargement of the bone may be due to the formation of an 

 alveolar abscess, or to increased deposition of crusta-petrosa 

 (see Tumours). Thus in the lower jaw the submaxillary bone 

 will present a prominence external to the offending tooth. This 

 bulging portion of the bone, when caused by an alveolar abscess, 

 as well as the soft structures external to it, will ulcerate, thus 

 giving exit to the pus. 



Caries of the superior molars, when commencing at the 

 fang, is usually associated with a discharge of foetid purulent 

 matter from the nostril of the side affected; this symptom 

 may be present before those portions of the tooth outside the 

 gums present any signs of decay. When caries of the fang 

 attacks a first or second superior molar, the superior maxillary 

 bone will present an enlargement similar to that already noticed 

 in the inferior maxilla, with sometimes an ulcer of communi- 

 cation. 



The fang may be absorbed without suppuration ; if such be 

 the case, the tooth will sink below the level of its fellows ; but 

 there will be no external enlargement, no alveolar abscess, nor 

 ulceration of the bone. 



Mr. Varnell says that the irritation of the fangs may give rise 

 to fibro-osseous tumour, which may either project into the 

 antrum, and partially or wholly fill that cavity, or into the 

 mouth, interfering thereby with the process of mastication. 



Again, caries of the fangs may extend outwards to the 

 maxillary bones, causing immense gaps of ulceration in them, 

 as shown in Photo-lithograph, Plate I., Fig. 7 ; or the ulcera- 



