Page 687 - The Veterinary Care of the Horse
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Figure 15.16 Lumps of mucus are commonly found on the ground outside the stable door
Once a horse has become sensitized, it may suffer acute attacks of the disease and develop
severe respiratory difficulties in a short period of time. The animal breathes with flared
nostrils and heaving flanks and has spells of continuous paroxysmal coughing. Wheezing
sounds may be heard at the nostrils.
The incidence of the disease increases with age.
Why does this develop?
The expiratory difficulty is caused by obstruction of airflow in both the large and small
airways. This is due to spasm of the smooth muscle (bronchospasm) in the larger airways and
inflammation and the accumulation of mucus in the bronchioles. Both lead to a reduction in
