Merck Manual

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Diagnosing Lung and Airway Disorders in Horses

Diagnosing Lung and Airway Disorders in Horses

Type of Test

How Used

Endoscopic examination

Allows the veterinarian to directly view the upper respiratory tract, guttural pouches, trachea, and upper airways of the lungs. Reasons for endoscopic examination include upper airway noise, difficulty inhaling, poor exercise performance, and 1- or 2-sided nasal discharge.

X-rays of the skull

Used to investigate facial deformity, abnormalities of the sinuses, guttural pouch, and tissues at the back of the mouth and throat.

X-rays of the neck

Used to investigate possible airway obstruction.

Transtracheal wash

Used to obtain secretions for bacterial and fungal culture.

Bronchoalveolar lavage

Used to obtain respiratory secretions for microscopic examination.

Nasal swab culture

Used to obtain samples for bacterial culture.

X-rays of the chest

Detects abnormalities of the lungs, heart, and diaphragm.

Chest ultrasonography

Used to identify the volume, location, and character of fluid or air within the chest cavity.


Sampling of fluid from the chest cavity; guided by ultrasonography.

Lung biopsy and fine needle aspirate

Used to obtain tissue samples for final diagnosis of lung tumors, lung fibrosis, and other disease.