Antimicrobial discontinuation in dogs with acute aspiration pneumonia based on clinical improvement and normalization of C-reactive protein concentration.

Background: Evidence regarding optimal treatment duration in dogs with aspiration pneumonia (AP) and the role of thoracic radiographs (TXR) and lung ultrasonography (LUS) in the long-term follow-up of affected dogs is lacking. C-reactive protein (CRP) is a reliable acute phase protein to monitor bacterial pneumonia in dogs.

Hypothesis: Investigate the safety of antimicrobial discontinuation based on clinical improvement and serum CRP normalization, as well as the usefulness of TXR and LUS for follow-up.

Animals: Dogs diagnosed with AP and treated with antimicrobials.

Methods: Prospective observational study. Antimicrobials were discontinued based on clinical improvement and serum CRP normalization after 1, 3, or 5 weeks. At each consultation, a quality-of-life questionnaire, physical examination, serum CRP, TXR, and LUS were assessed. Short- (2 weeks) and long-term (>1 month) follow-ups after treatment discontinuation were performed to monitor for possible relapses.

Results: Seventeen dogs were included. Antimicrobials were discontinued after 1 week in 12 dogs (70.6%) and 3 weeks in the remaining 5 dogs (29.4%). Short-term relapse was not observed in any dog and long-term relapse was diagnosed in 3 dogs. Thoracic radiographs and LUS were useful for diagnosis, but did not add additional information during follow-up, because image normalization lagged behind clinical improvement and serum CRP normalization.

Conclusion And Clinical Importance: Dogs with AP can be safely and effectively treated using a short-term antimicrobial regimen discontinued after clinical improvement and serum CRP normalization. Imaging might still be useful for complicated cases with a less favorable response to treatment.