There is no significant difference in the treatment of aspiration pneumonia in dogs with ampicillin-sulbactam versus ampicillin-sulbactam and enrofloxacin.

Objective: Describe outcomes for dogs with aspiration pneumonia (AP) initially treated with ampicillin-sulbactam (AS) alone (monotherapy [MT]), initially with AS and enrofloxacin (initial dual therapy [iDT]), or initially with AS and later escalating with enrofloxacin (escalated dual therapy [eDT]).

Methods: Retrospective review of dogs hospitalized at a teaching hospital for AP between 2010 and 2022. Inclusion criteria included consistent historical and thoracic radiographic findings and subsequent treatment with MT, iDT, or eDT. Exclusion criteria included radiographic findings suggesting other pulmonary pathologies, aspiration while hospitalized, antibiotic use in the prior month, or referral for comorbidities. Demographics, weight, vital signs, laboratory data, thoracic radiographs, lung lobes affected, antibiotic timing, and hospitalization details were recorded. Shock index, systemic inflammatory response syndrome criteria, and quick sequential organ failure assessment scores were calculated.

Results: 58 dogs met inclusion criteria. A total of 40 dogs were started on AS alone; 27 dogs were assigned to MT (46.6%). Thirteen dogs were later escalated (eDT; 22.4%). Eighteen dogs (31%) received iDT. The dogs that were escalated had significantly longer hospital stays. However, no significant differences were observed in lung lobes affected, survival to discharge, disease severity indices, and total leukocyte counts across the 3 groups. No differences were found between survivors and nonsurvivors.

Conclusions: Ampicillin-sulbactam alone is an effective treatment for a substantial proportion of dogs with AP.

Clinical relevance: Empirical treatment with MT is likely appropriate for dogs with AP lacking signs of critical illness. In dogs for which eDT was deemed clinically necessary, outcomes are not worse.