Abstract
Pulmonary atelectasis is common following general anesthesia in dogs, often due to reduced functional residual capacity, oxygen absorption, and surfactant dysfunction. This study evaluated an ultrasound-guided alveolar recruitment maneuver (ARM) using incremental positive end-expiratory pressure (PEEP) in anesthetized client-owned dogs with ultrasound-confirmed atelectasis. Dogs were assigned to two groups: mechanically ventilated (MV) or spontaneously breathing (SB). Following anesthesia, lung ultrasound atelectasis scores (LUAS) were recorded post-procedure and during recruitment, which began at PEEP 5 cm H₂O, incrementally increasing by 3 cm H₂O every two minutes until atelectasis resolved. Hemodynamic and ventilatory parameters were recorded. Each group included 15 dogs. SB dogs were younger and had shorter anesthesia duration than MV dogs. Heart rate increased significantly at PEEP11 (SB) and PEEP14 (MV). Et’CO₂ rose in the SB group during early recruitment. Peak inspiratory pressure and compliance were significantly lower post-recruitment (p < 0.0001). Regional LUAS was significantly higher post-procedure than during recruitment, indicating effective atelectasis resolution. Total LUAS was higher in MV dogs than SB dogs. This study demonstrates that ultrasound-guided LUAS is a reliable, non-invasive tool for detecting and monitoring pulmonary atelectasis in dogs, and effectively guides individualized ARM protocols to improve perioperative respiratory care. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-35202-4.