OSTERO-POROSIS. 
587 . 
one location to another, where the change seemed to arrest 
the progress of the disease, where the lameness subsided and 
the animals remained able to do their work for years after. A 
client of mine a few days ago, whose word can be relied upon, 
told me of a certain horse which I told him to dispose of 
some two years ago, having osteo-porosis so well marked that 
he himself noticed the enlargement of the facial bones first, and 
which had been sold to a farmer at that time. He had seen the 
horse recently, and the swelling of the bones of the head had 
disappeared, and the horse was doing good service for his 
present owner. 
As to the period of incubation and length of time it takes to 
render the animal useless if kept in the same stable and under 
the same conditions, I should say from three to twelve months. 
As to whether the disease can be transmitted from sire or 
dam to offspring, I am not prepared to say, as my practise is 
exclusively in the city, and the early history of the cases I 
have seen could not be traced. 
I do know of two cases, however, where mares suffering 
from osteo-porosis had good healthy colts last spring and 
both colts up to this time are apparently in perfect health, 
both mares being dead. 
According to Williams, Varnell was the first man to de¬ 
scribe this disease in i860 and it seems reasonable to suppose 
that it did not exist to any great extent prior to that in En¬ 
gland. I am satisfied that there was none of it in Percival’s 
time, for he was as careful an observer and as brilliant a writer 
as has ever contributed to veterinary literature. 
In this country I believe it to be of comparatively recent 
origin. The very fact that Dr. Hausman had never seen a 
case prior to 1879, would strongly point in this direction. 
As to causes : Considering the cases that have come under 
my observation, and more particularly the conditions and lo¬ 
cation of the stables in which these cases were found, I cannot 
help but conclude that a specific germ, vegetable or mineral, 
or perhaps a gas, the development or generation of which is 
favored by certain soils and certain conditions, are the most 
probable causes; and that this substance, whatever it may be, 
finds its way into the body of animals, acts specifically upon 
