Determining the cause of pulmonary disease can be a challenge for veterinarians. Clinicians are limited in that evaluation of thoracic radiographs does not always reveal lesions, diffuse radiographic changes are nonspecific, and radiographic lesions may represent old, clinically inactive lesions.1,2 Ancillary diagnostic tests are almost always warranted in patients with respiratory tract disease.1 Bronchoscopy allows visual examination of the bronchi, and BAL can be used to collect samples from the alveoli for cytologic, biochemical, and microbiological evaluation. These techniques are relatively safe, and they have been commonly used for evaluation of the bronchi and alveoli of dogs for > 20 years.1,3–6
Indications for bronchoscopy and BAL include chronic cough, unexplained changes evident on thoracic radiographs, and pulmonary masses.1,3,5 The basic technique for BAL consists of infusing sterile saline (0.9% NaCl) solution into the bronchi and alveoli, which is then followed by aspiration of the infusate1,5; however, the procedure varies3,4,7 and there are no standardized protocols for small animals. Responses of 28 Diplomates of the American College of Veterinary Internal Medicine to an email survey conducted in September 2011 revealed that anecdotally there was great variation for the type of endoscope used, fluid volume for BAL, and aspiration technique. Analysis of the available evidence has indicated that technical aspects of BAL, such as the interval from collection until sample processing and analysis, affect the quality of the sample.8,9 Sample quality is important to ensure meaningful cytologic analysis and diagnosis. One aspect of BAL, which has not been previously evaluated in dogs, is aspiration technique for fluid retrieval. Currently, there are 2 commonly used techniques for retrieval of BALF: MA and SPA.1,3 In human medicine, SPA with negative pressure of 25 to 100 mm Hg to collect BALF in a fluid trap is the most commonly used method.10–12 In contrast, MA with a syringe is the most commonly reported technique in veterinary medicine.3,5,7,9 There are variations in MA with regard to the size of syringe and use of sterile polyethylene tubing passed through the biopsy channel of a bronchoscope.1,3,5
The purpose of the study reported here was to compare MAPT and SPA via suction trap connection for collection of BALF in healthy dogs and the effect of these techniques on BALF sample quality. We hypothesized that the method of BALF aspiration would influence sample quality and therefore potentially influence the diagnostic utility of examination of BALF in dogs.
Bronchoalveolar lavage fluid
Manual aspiration via polyethylene tubing
Suction pump aspiration
Arnolds dog catheter with female Luer mount, 8F × 50 cm, Smith Medical International, Hythe, Kent, England.
Olympus BF type 1T160 video bronchoscope, Olympus Canada Inc, Richmond Hill, ON, Canada.
Olympus SSU-2 endoscopic aspiration pump, Olympus Canada Inc, Richmond Hill, ON, Canada.
Kendall Luki 20-mL (6.25-inch) disposable aspirating tube, Tyco Healthcare Group, Mansfield, Mass.
Intramedic Clay Adams polyethylene tubing (inner diameter, 0.034 inches; outer diameter, 0.060 inches; wall thickness, 0.013 inches), Becton Dickinson, Franklin Lakes, NJ.
Video bronchoscope cleaning and cold sterilization protocol, Olympus Canada Inc, Richmond Hill, ON, Canada.
Endozime, dual enzymatic cleaning, Ruhof Corp, Mineola, NY.
Glutacide, Pharmax Ltd, Etobicoke, ON, Canada.
Z2 Coulter counter, Beckman Coulter, Mississauga, ON, Canada.
Shandon Cytospin 4, Thermo Fisher Scientific Inc, Waltham, Mass.
Olympus BX53 system microscope, Olympus Canada Inc, Richmond Hill, ON, Canada.
SAS, version 9.1, SAS Institute Inc, Cary, NC.
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Criteria used for microscopic assessment of quality of cytocentrifuge preparations of BALF collected from healthy Beagles.
|Cellularity (No. of cells/slide)||0||< 10|
|1||10 to 100|
|2||101 to 200|
|3||201 to 500|
|Cell preservation (% of well-preserved cells/slide)||0||< 10|
|1||10 to 25|
|2||26 to 50|
|3||51 to 80|
|Epithelial cells (No. of cells/slide)||0||Absent|
|2||51 to 100|
|3||101 to 200|
|RBCs (% of cells/slide)||0||≤ 1|
|1||2 or 3|
|2||4 or 5|
|Bacteria (No. of cells/slide)||0||Absent|
|2||6 to 10|
|3||11 to 20|