Respiratory ailments are relatively common in animals. Many diseases are diagnosed by blood tests, radiographs (X-rays) or ultrasound, but some diseases escape diagnosis and need additional tests. Bronchoalveolar lavage (BAL) is a test in which fluid samples from the bronchus and alveoli (air sacs) are obtained. These fluid samples are then submitted for analysis to help determine the underlying cause of illness.

A BAL is indicated when the airways need further investigation. This test can be used to determine the cause of abnormal lung or airway function. Most often, BAL is used to help diagnose respiratory abnormalities caused by infections, inhaled foreign objects, cancer or inflammatory lung disease. A BAL allows for collection of a large volume of fluid obtained from the lower airway.

The BAL should be avoided in animals with respiratory disease so severe that anesthesia is too risky.

What Does a Bronchoalveolar Lavage Reveal?

A bronchoalveolar lavage helps determine if abnormal cells, fluid, fungi or bacteria are present within the airways and air sacs of the lung. The results of the bronchoalveolar lavage can help determine the best course of treatment.

How Is a Bronchoalveolar Lavage Done?

After being placed under general anesthesia, an endotracheal (breathing) tube is placed in the trachea. The BAL is generally preformed one of two ways. The first is by using a bronchoscope (rigid tube with a camera on the end), which is placed through the endotracheal tube and advanced into the large airways of the lung. In cats, it is often impossible to pass the bronchoscope very far past the largest airways due to their small anatomic size. If possible, the bronchoscope is then used to find an abnormal area within the airways and allow for directed specimen collection. About 20 to 30 milliliters of sterile saline solution is passed through the channel on the bronchoscope. This fluid is then retrieved and submitted for analysis. This method requires specialized equipment. The second method to perform a BAL is fluid collection obtained directly though the endotracheal tube.

Various analyses can be performed on the fluid. Bacteria can be detected and various cells can be examined microscopically. Though the test is completed in about 1 to 2 hours, test results may not be available for up to 3 to 5 days.

Is a Bronchoalveolar Lavage Painful?

Since the procedure is performed under anesthesia, there is no pain involved. There is no incision so there is no pain after the procedure. Some discomfort may occur due to the temporary placement of the breathing tube. This varies from individual to individual.

Is Sedation or Anesthesia Needed?

General anesthesia is necessary to perform a bronchoalveolar lavage. General anesthesia will induce unconsciousness, complete control of pain and muscle relaxation. The pet may receive a pre-anesthetic sedative-analgesic drug to help him relax, a brief intravenous anesthetic to allow placement of a breathing tube in the windpipe, and subsequently inhalation (gas) anesthesia in oxygen during the actual procedure.