The study investigated whether transdiaphragmatic pressure (Pdi) differs between dogs with cervical myelopathy (CM) and thoracolumbar myelopathy (TLM) under isoflurane anesthesia. In this prospective cohort study, ASA II dogs diagnosed with either CM or TLM and undergoing anesthesia for diagnostic or surgical procedures between September 2021 and July 2023 were enrolled. A uniform anesthetic protocol was applied. Transdiaphragmatic pressure was measured using balloon catheters placed in the stomach (Pgast) and mid-esophagus (Poes), with peak Pdi recorded at 10 (Pdimax10), 20 (Pdimax20), and 30 (Pdimax30) minutes. Fifty dogs were included, with 25 in each group. For the TLM group, Pdimax10 was 9.4 ± 6.1 mmHg, compared with 7.2 ± 4.6 mmHg in the CM group (p = 0.167). Pdimax20 values were 10.2 ± 5.8 mmHg in TLM and 8.0 ± 5.1 mmHg in CM (p = 0.155). At 30 minutes, Pdimax30 was 9.2 ± 5.5 mmHg for TLM and 8.1 ± 5.5 mmHg for CM (p = 0.479). The data indicate that diaphragmatic function under isoflurane anesthesia is similarly affected in dogs with cervical and thoracolumbar myelopathy, with no statistically significant differences between the two groups.
