CHAPTER XX. 
DISEASES OF THE BONES. 
1. Big Head (Osteo-Porosis). 
This disease is more common in some localities than in 
others. It is not prevalent in Canada or Great Britain, but 
is quite so in the United States and Mexico. It is a disease 
which attacks horses from one to four years old, rarely old 
horses. It develops gradually as the animal grows, without 
any signs of soreness, the bones of the head and legs becom- 
ing larger, lighter and very brittle, or easy to break — thus 
the term "big." It affects the bones of the head more fre- 
quently than those of any other part of the body. 
Causes. — It is difficult to say what is the real cause of 
this disease, but it is supposed to be caused by feeding on 
pasture land deficient in the salts of lime. Some believe it to 
be wholly caused by grazing on low-lying, swampy land, 
where the grass grows long and does not contain the full 
amount of nourishing substances. 
Symptoms. — In the earlier stages the symptoms are not 
well marked. There is dullness, loss of flesh and softening of 
the muscles. In from four to six months the true nature of 
the disease becomes evident. There is a stiffness when 
traveling and very gaunt appearance accompanied by an 
enlarging of the head, soon followed by enlargement of the 
bones of the legs. As the disease progresses these symptoms 
increase. The animal loses flesh until after a gradual decline 
he dies. In some cases the bones of the legs become so 
brittle that they break while traveling. 
Treatment. — The treatment of osteo porosis up to the 
present has not been attended with but little success, more 
especially if allowed to go for any length of time before tak- 
ing the matter in hand. In the earlier stages if he is on low 
pasture move him to high ground, and give a tcaspoonful of 
sulphate of iron in some oats twice a day to buiH tip the 
system and counteract the effect of the discMe. 
