262 DISEASES OF BONE. 



have seen, both sides of the face have been affected. In the 

 exceptional instances, which I saw only in their early stage, the 

 enlargement had appeared quite suddenly. I do not think there 

 is any definite rule as to the speed with which this growth 

 increases. I have known instances in which it appeared very 

 slightly; remained quiescent for some months; and then rapidly 

 increased until the animal shortly afterwards died from the 

 disease. In cases of recovery, the enlargement of the face persists, 

 unless the advance of the malady be checked in a veiy early stage, 

 when the swelling may disappear. When the enlargement is well 

 marked, it gives the face a flattened and swollen appearance. 

 The bones of the lower jaw are, also, generally swollen. In the 

 cases I have seen, the bones of the face, below the eyes, were the 

 only ones which Avere visibly affected. 



The mucous membrane of the mouth a^ppears swollen and pale, 

 and is covered with a copious supply of dirty-looking mucus. 

 With the advance of the disease in the bones of the lower jaw, 

 the teeth become loose. I have seen some good instances in young 

 horses, of dentition being retarded to a marked extent by this 

 complaint; that is to say, the mouth showed the animals to be 

 a year or more younger than they were. 



Soon after, and occasionally before, the swelling of the bones of 

 the face has become manifest, the animal may be observed to go 

 stiffly " all roimd " ; and the consequent lameness is generally 

 associated with well-marked loss of condition. In the usual 

 course, this stiffness will soon unmistakably assume the character 

 of general paralysis, Avhich, according to some authorities, is due 

 to the bones becoming so wanting in tenacity that they lose 

 their power of affording sufficiently firm attachment for the 

 various tendons and ligaments. Bland Sutton's theory of pressure 

 on the spinal cord being the cause of the paralysis of rickets (p. 

 266), may also be applicable to that of osteoporosis. When in- 

 vestigating this point post tnortem, Ave should make transveirse 

 sections through the A^ertebrse, so as to see if their calibre has 

 become narrowed by the inAvard sAvelling of the bone. 



I have found in two or three cases Avhich had recovered, that 

 the resulting alteration in the nasal passages made the horse a 

 confirmed " roarer," 



APPEARANCE AFTER DEATH.— The enlarged bones are ab- 

 normally vascular and extremely brittle. 



CAUSES. — I believe feeding on innutritious grass to be one 

 of the chief causes of this disease, and have observed in all the 

 cases I have seen, Avhich have amounted to many score, that the 



