Page 688 - The Veterinary Care of the Horse

airway diameter so breathing requires more effort. These changes occur within a few hours of

a susceptible horse being placed in a stable environment.
VetBooks.ir time. The chronic inflammation leads to thickening of the mucosal lining of the bronchiolar
If the disease is not controlled, structural changes occur in the lungs over a period of

walls and proliferation of the smooth muscle in the airway walls. In severe, long-term

disease, the alveoli become over-inflated and emphysema can develop. The horse is
colloquially described as ‘broken-winded’.

When to call the vet

Call the vet at the first sign of the disease. Early diagnosis, treatment and management
changes often prevent it from developing into a serious problem.

Diagnosis

The diagnosis is made on the history and the clinical signs. In mild cases the vet may not
hear any abnormal sounds with the stethoscope. In severe cases, a wide range of lung sounds

including crackles and wheezes may be heard.

If the upper respiratory tract is examined with an endoscope, a stream of mucopus may be
seen in the trachea (Figure 15.17). Examination of airway secretions taken by
bronchoalveolar lavage reveals large numbers of neutrophils when compared with secretions

obtained from an unaffected horse.