Propofol Requirements for Induction of Anaesthesia in Dogs with Cervical or Thoracolumbar Myelopathy Due to...

Background: The aim of the present retrospective observational study is to compare the required doses of propofol (PPF) for anaesthesia induction in dogs presented with intervertebral disc disease (IVDD)-related thoracolumbar or cervical myelopathy. Methods: The anaesthetic records of dogs with either cervical- or thoracolumbar-related myelopathy anaesthetised for diagnostic or surgical procedures from September 2021 to July 2023 were evaluated. Inclusion criteria were premedication with the same dose of dexmedetomidine (DEX) (180 μg m^-2), and induction with PPF. The sedation score (SS), Glasgow Composite Measure Pain Scale-Short Form (GCMPS-SF) results and the total PPF dose required for intubation were collected. Data were analysed with the Shapiro-Wilk test, independent samples t-test and Spearman's rho test. A value of p < 0.05 was considered statistically significant. Results: Fifty-five records were included in the study, 27 dogs with cervical and 28 with thoracolumbar myelopathy due to IVDD. Statistically significant higher doses of PPF were required in the dogs with cervical (mean 3.2 mg kg^-1, ±SD 1.25 mg kg^-1) than with thoracolumbar (mean 1.9 mg kg^-1, ±SD 0.65 mg kg^-1) myelopathy (t-test, p < 0.001). The SS in the dogs with cervical-cervicothoracic myelopathy (CCTM) (median 6, ±min 2 max 10) also differed from the SS of the dogs with thoracolumbar myelopathy (TLM) (median 7.5, min 2 max 12) (t-test, p = 0.02). Sedation score and the dose of PPF were significantly negatively correlated (Spearman's rho -0.311, p = 0.021). Sedation score and GCMPS-SF were also significantly negatively correlated (Spearman's rho -0.363, p = 0.007). However, no statistically significant negative correlation was found between PPF dose and GCMPS-SF score (Spearman's rho = 0.248, p = 0.068). Conclusions: Our findings should be considered when planning anaesthetic protocols in patients suffering from IVVD-related myelopathy in order to optimize safety in these patients.