CLINICAL VETERINARY MEDICINE AND SURGERY. 



examination, was found to consist of four molar teeth ; the two lower 

 had developed from the region of the sella turcica, and compressed 

 portions of the brain, which in this situation, as is known, is very 

 intolerant of injury. Monsieur Barreau published the history of a 

 horse which, after long suffering from a temporal sinus, showed 

 difficulty in mastication, general wasting, and unmistakable signs of 

 some brain lesion. It was slaughtered. In the cranium was found a 

 kind of bony new formation, hemispherical in shape, developed from 

 the squamous temporal bone and the corresponding wing of the 

 sphenoid. 



The anatomico-pathological characters presented by even the 

 more benign of these lesions vary greatly. They may resemble 

 dermoid cysts, abscesses, or recent or old-standing fistulae. The cyst 

 generally contains only one tooth. Sometimes, however, there may be 

 two, three, or more, either distinct or fused together. They usually 

 present the appearance and characters of molars ; in other cases they 

 more closely resemble incisors. Their shape is either prismatic, 

 pyramidal, or rounded ; the majority, however, are very irregular. In 

 composition they do not essentially differ from normal teeth, dentine, 

 enamel, and cement being associated in varying proportions, the 

 dentine usually predominating. 



The firmness with which these teeth are fixed in position varies 

 greatly. In certain cases, as in that seen by you, extraction is 

 easy. In others it is difficult, and not without danger. In a two-year 

 colt Degive, after removing one tooth, discovered a more deeply 

 placed eburnated swelling, formed by several teeth incompletely fused 

 together. The removal of this growth opened the cranial cavity, its 

 lower portion being in direct contact with the dura mater. 



Provided the nature of these cysts and sinuses in the temporo- 

 auricular region is recognised, the operator is less likely to commit 

 indiscretions. Without doubt, in this as in other regions, ordinary 

 cystic swellings develop sinuses, and are kept discharging by the 

 presence of bony or cartilaginous necrosis ; but such accidents are 

 infinitely rarer than those consequent on dental irregularities. 



Several cases described as necrosis of the scutiform cartilage — 

 Martin's among others — and some referred by the writers to in- 

 flammatory changes of the temporal bone, can now safely be assigned 

 to the presence of supernumerary teeth. If, before intervention, one 

 hesitates between diagnosing a dental cyst or necrosis of bone, it 

 should be borne in mind that the former hypothesis is by far the more 

 probable. When the swelling embraces the base, and extends more 



