Antimicrobials’ topical administration efficacy has not been assessed in dogs with upper respiratory tract disease. The aim was to compare the concentration of gentamicin in nasal lavage fluid (NALF) and in serum after three topical protocols. This was a prospective crossover study of ten healthy dogs. Gentamicin was nebulized for a duration of 1 week, twice a day, for 10 min in the first protocol (10-min protocol) and for 3 min in the second protocol (3-min protocol), while the third protocol consisted of the administration of 0.25 mL of gentamicin in each nostril (drop protocol). Median concentrations of gentamicin in NALF were 9.39 µg/mL (8.12–19.97 interquartile range), 4.96 µg/mL (4.60–6.43) and 137.00 µg/mL (110.5–162.00) in the 10-min protocol, 3-min protocol and drop protocol, respectively. The result for the drop protocol was significantly higher than those of both nebulization protocols in NALF (p = 0.039). In serum, the gentamicin concentration was 0.98 µg/mL (0.65–1.53) and 0.25 µg/mL (0.25–0.44) in the 10-min and 3-min protocols, respectively. Gentamicin was not detected in the serum of seven out of ten dogs in the drop protocol, and gentamicin was significantly higher in the 10-min protocol compared to the drop protocol (p = 0.001). This study found that the 10-min, 3-min and drop protocols achieved superior concentrations in NALF compared to the minimum inhibitory concentration for gentamicin-sensitive bacteria, while remaining below the toxic values in blood.

Background: Bronchoalveolar lavage fluid (BALF) analysis is a key diagnostic tool in veterinary respiratory medicine. The IDEXX ProCyte Dx analyzer was developed for blood formulation and cellular counting in various fluids, but its applicability for BALF analysis remains unexplored. Objectives: To assess the agreement between manual counting and automated counting using the IDEXX ProCyte Dx analyzer for total cell count (TCC) and differential cell count (DCC) in BALF samples from healthy and diseased dogs, under two pretreatment conditions: mucolytic treatment with dithiothreitol (DTT) or filtration. Methods: BALF from 10 healthy beagles and 14 diseased dogs were analyzed to compare TCC and DCC between manual and automated methods across pretreatment conditions. Results: In healthy dogs, Bland–Altman analysis on log‐transformed data demonstrated a mean ratio close to 1 and acceptable 95% limits of agreement between manual and automated methods and between pretreatment conditions. In diseased dogs, good agreement was observed between manual and automated methods for filtered samples only; the other comparisons showed poor agreement. In both healthy and diseased dogs, Passing‐Bablok regression analysis did not detect systematic or proportional bias between methods. Automated DCC was inconsistent compared with manual methods in both healthy and diseased dogs. Conclusions: The IDEXX ProCyte Dx analyzer can be used for TCC measurement of pre‐treated BALF samples in healthy dogs. In diseased dogs, filtration is preferred over DTT‐treatment for automated counting, and results should be interpreted with caution due to the unpredictable influence of pretreatment on cellular counts. For DCC, automated methods are unreliable.