Changes

On physical examination, thoracic auscultation typically reveals a prolonged expiratory phase of respiration and adventitious respiratory noises. Wheezes are most pronounced during expiration, and crackles are associated with the excessive mucus production^merck. However, the airways are so obstructed in some severely affected animals that there is insufficient air movement to generate audible breath sounds, and the lungs are very quiet on auscultation¹. In mildly affected horses, a rebreathing bag can be used to aid auscultation, but this should never be performed in dyspnoeic animals^{1, allen}. There may be an increased sensitivity of the cough reflex on tracheal compression.

On physical examination, thoracic auscultation typically reveals a prolonged expiratory phase of respiration and adventitious respiratory noises. Wheezes are most pronounced during expiration, and crackles are associated with the excessive mucus production^merck. However, the airways are so obstructed in some severely affected animals that there is insufficient air movement to generate audible breath sounds, and the lungs are very quiet on auscultation¹. In mildly affected horses, a rebreathing bag can be used to aid auscultation, but this should never be performed in dyspnoeic animals^{1, allen}. There may be an increased sensitivity of the cough reflex on tracheal compression.

===Diagnostis Imaging===

===Diagnostic Imaging===

Endoscopy reveals excessive mucopurulent secretions in the trachea. Thoracic radiographs may be useful in cases that are not typical in their presentation or response to treatment, as they may help rule out other differentials such as including interstitial pneumonia, pulmonary fibrosis, or bacterial pneumonia^{1, allen}.

are recommended in animals that do not respond to treatment

as anticipated, as they are useful to rule out other

types of lung disease and, in some cases, may show evi-dence of irreversible lung

of RAO.

merck Radiographic findings in horses with RAO are peribronchial infiltration and overexpanded pulmonary fields (flattening of the diaphragm). Thoracic radiographs are of little benefit in confirming the diagnosis of RAO and may not be necessary in horses with characteristic clinical signs, unless there is no response to standard treatment after 14 days of therapy. However, they may be helpful in identifying the most important differential diagnoses, including interstitial pneumonia, pulmonary fibrosis, or bacterial pneumonia.

merck Radiographic findings in horses with RAO are peribronchial infiltration and overexpanded pulmonary fields (flattening of the diaphragm). Thoracic radiographs are of little benefit in confirming the diagnosis of RAO and may not be necessary in horses with characteristic clinical signs, unless there is no response to standard treatment after 14 days of therapy. However, they may be helpful in identifying the most important differential diagnoses, i

===Laboratory Tests===

===Laboratory Tests===