DENTITION AND DENTAL DISEASES 237 



ally to a great extent ? If we take into consideration the disorder 

 and fever set up in some children during teething, and the nervous 

 exhaustion and complaints arising therefrom, need we be at all 

 surprised to notice at this period the commencement of several 

 nervous derangements in the horse ? 



350. Having had ample opportunities of inspecting animals, from 

 foals upwards, I find it very rare tjiat any sign or symptom of 

 chorea, shivering, string-halt, or clicking {par. 598) occurs 

 until the animal is rising three years old. From long observation 

 I am, therefore, inclined to think that in the irritation set up during 

 the extensive dental processes just referred to will be found the 

 cause and the commencement of these nervo-muscular derangements, 

 through a reflex nervous action that is set up, more particularly so 

 when there is a hereditary tendency thereto. The most critical 

 period, therefore, in the life of a horse is when it is rising three years 

 old, for not only are there associated with it at this period the above- 

 mentioned complaints, but also strangles ; though whether the 

 latter is partially due to extensive dentition, or to the change from 

 outdoor to indoor life, or to the two combined, I am scarcely able 

 to say ; yet I am inclined to think that teething, in certain instances, 

 has something to do with the cause. Again, at this period, if the 

 true process of dentition is not going on, there may be abscesses 

 formed at the root of the tooth, or in the sinuses, with disease of the 

 alveolar processes — more particularly in the upper jaw — and ending in 

 softening and degeneration of the bone, or bony tumours may form 

 on the tooth itself. Plate XXXI. , No. 3, represents a tumour on 

 the crown of the fourth upper or first permanent molar tooth, due 

 to extensive inflammation and degeneration of the bones of the face 

 of a three-year-old filly. 



351. Shortly after I commenced practice a three-year-old cart 

 colt was brought to me in a very emaciated condition for the pur- 

 pose of having its lampers burnt or cut. On looking into the 

 mouth, I saw the crowns of the first and second temporary pre- 

 molars sticking on the top of the permanent teeth, which were well 

 up above the gums. Here, then, was the cause of the poor condition 



