OSTEOPOROSIS. 261 



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 investi- 

 gating this point post mortem, transverse sections should be made 

 through the vertebrae, so as to see if their calibre has become 

 narrowed by the inward swelling of the bone. 



In two or three cases which recovered, the resulting alteration 

 in the nasal passages made the horse a confirmed " roarer.'' 



APPEARANCE AFTER DEATH.— The enlarged bones are 

 abnormally vascular and extremely brittle. 



CAUSES. — Feeding on innutritious grass is probably one of 

 the chief causes of this disease, and in all the' cases I have seen, 

 which have amounted to many score, the sufferers had been 

 previously kept on this kind of fodder. This fact was well 

 exemplified in Hongkong, where the Happy Valley forms the 



Fig. 99. — Pear-shaped firing iron. 



only pasture-land. As this is a more or less flat piece of ground, 

 about \\ mile round, nearly on the level of the sea, and as it 

 receives almost all the water which drains oft' the sides of the 

 neighbouring hills; the grass on it, in that tropical climate, is, 

 naturally, very coarse and rank. OnC' gentleman had five ponies 

 that died from this disease, all had shown symptoms of it only 

 after having been turned out to graze in the Happy Valley. He 

 had no case of it among those ponies which had not been turned 

 out. While in the colony, I met other liorse owners whose 

 experience was similar to that of this gentleman. The effect of 

 a damp climate on the grass of districts in Hawaii is to render 

 such herbage innutritious. 



In India I had a lately-imported five-year-old Australian mare, 

 which was put on green grass, as she was in bad condition. After 

 being on this diet for about three weeks, she became listless, 

 slightly paralysed, and quickly developed the characteristic 

 swelling of osteoporosis on one side of the face. She was at 

 once fed on hay made from young oats ; the enlargement subsided, 

 and the mare got all right in a few days. 



I saw on one occasion at the Bahawulpore Stud Farm a great 



