(roaring).

_The common causes_ of heaves are pre-existing diseases of the respiratory
organs, severe exercise when the animal is not in condition and wrong
methods of feeding. Heaves is more common in horses that are fed heavily on
dusty timothy and clover hay and allowed to drink large quantities of water
after feeding, than in horses that are fed green feeds, graze on pastures
or receive prairie hay for roughage. Chronic indigestion seems to aggravate
the disease. Over-distention of the stomach and intestines due to feeding
too much roughage and grain interferes with respiration. Severe exercise
when in this condition may result in over-distention, dilation and rupture
of the air cells. This is the most common structural change met with in the
lungs of horses affected with heaves. It is termed emphysema.

_The common symptoms_ noted are the double contraction of the muscles of
the flank with each expiration, a short, dry cough and the dilated
nostrils. The frequent passage of gas is a prominent symptom in
well-established cases of heaves. Chronic indigestion is commonly present
in heavy horses that are not well cared for, or are given hard work. This
condition aggravates the distressed breathing.

Heaves is a permanent disorder, but it may be relieved by climatic changes
and careful attention to the animal's diet.

The following _preventive treatment_ is recommended: Dusty hay should not
be fed to horses. Clover hay is not a safe feed for horses that are worked
hard. When starting on a drive after feeding, the horse should not be
driven fast, but allowed to go slowly for a few miles.

The symptoms can be greatly relieved by careful attention to the diet. A