Obtaining bacterial culture samples in pneumonia patients is important but can be difficult. Small size and lack of cooperation can make transtracheal washes particularly challenging in puppies. Transoral tracheal wash (TOTW) and bronchoalveolar lavage are the gold standards for diagnosis but require general anesthesia and may be risky in severely compromised patients. In children, bacterial culture and sensitivity (BC&S) samples can be collected using a deep oral swab (DOS) technique, in which physiotherapy (mechanical stimulation) is used to induce cough and obtain deep throat culture. DOS might be an appropriate alternative to TOTW for obtaining BC&S samples in dogs. Five puppies and 5 dogs with clinical signs and radiographic findings consistent with pneumonia were enrolled in the study. Cough was induced by physiotherapy in each patient; DOS was collected from around the larynx and epiglottis via direct visualization. A second anesthetized sample was collected via standard TOTW techniques. Cytology and BC&S were conducted on all paired samples. Results demonstrated good concordance between DOS and TOTW in adult dogs with either complete (n = 2/5) or partial agreement (n = 2/5) in BC&S results. However, there was a complete lack of concordance between paired samples in puppies. The poor agreement in puppies may result from oral contamination of the throat swab, failure to obtain a representative sample, incorrect throat swab technique, puppy facial conformation, or inadequate physiotherapy. The good agreement in adult dogs may be caused by easier sample collection in larger patients. The adult dogs in this study had aspiration pneumonia, and the bacterial population in the oral cavity might resemble that of the lungs. Use of DOS samples warrants further investigation in adult dogs.

Commentary
This interesting pilot study was attempting to identify a potential means for cost reduction of sample collection and to qualify the need for anesthesia in dogs with signs of pneumonia. Oral and tracheal bacterial populations were poorly associated in the puppy group and strongly associated in the adult group. These results suggest that endotracheal sampling is still recommended in puppies with signs of pneumonia. However, oropharyngeal swab sampling may be representative of endotracheal populations in adult dogs with pneumonia, particularly those with high anesthetic risk. Additional cases need to be evaluated to improve statistical power of the hypothesis. Viral infections were not evaluated in this population.—Elke Rudloff, DVM, DACVECC

Source
The use of deep oral swabs as a surrogate for transoral tracheal wash to obtain bacterial cultures in dogs with pneumonia. Sumner CM, Rozanski EA, Sharp CR, Shaw SP. J VET EMERG CRIT CAR 21:515-520, 2011.