88 DISEASES OF THE TEETH. 



he was again placed under my care. On the 7th I cast him, 

 opened up the fistula, and found a broader tumour had de- 

 veloped beneath the seat of the first one. Its base was deep 

 and wide, and at every stroke of the mallet and chisel, the 

 horse indicated, from convulsive twitching and great struggles, 

 that the concussion was directly transmitted to the brain. 

 The tumour could only be partially removed, and the horse 

 thus proved incurable. It is evident, as Macrops has shown, 

 that several dental formations may succeed each other. 



Fortunately the incurable cases are few, but it is essential 

 to know the true nature of the disease, in order to direct our 

 remedies with effect. 



IRREGULARITIES IN THE Rows OF TEETH. There are 

 numerous irregularities in the direction of molar teeth. I 

 remember, during the period that I was a pupil at the 

 London Veterinary College, a colt was brought in, suffering 

 much from a molar tooth, which, instead of protruding on 

 the alveolar margin of the upper jaw, passed inwards through 

 the palate, and had grown a considerable length downwards 

 so as to press on the tongue. The animal could not eat, and 

 was destroyed for dissection. The head is still, I believe, 

 in the museum of the St Pancras College. 



The lower jaw is, as stated when on the subject of parrot- 

 mouth, sometimes shorter than the upper. This leads to an 

 imperfect apposition of the molars as well as of the incisors, 

 and the first molar on either side of the upper jaw is apt to 

 indicate excessive growth at the anterior part, and the same 

 happens with the back part of the last grinders on the lower 

 jaw. These projections may attain considerable length, and 

 inflict injury on the cheeks and tongue. 



By far the most common irregularity from imperfect wear 

 of the teeth depends on the breadth of the upper jaw as 

 compared with the lower. Frequently the outer margins of 



