ObjectiveTo determine whether dogs with magnetic resonance imaging (MRI)-determined intracranial space occupying lesions (MRI-iSOLs) or intracranial hypertension (MRI-ICH) had greater sedation scores and quicker onset of recumbency following premedication with intravenous (IV) butorphanol in comparison with dogs which had normal MRI findings. Study designProspective, observational study. AnimalsA total of 53 dogs presenting for brain MRI were included. MethodsEach dog was sedated with 0.2 mg kg–1 butorphanol IV, and the quality of sedation and the onset of recumbency were scored before drug administration and every 5 minutes after IV butorphanol administration for 15 minutes using a modified sedation scale. The maximum sedation score was 18, and onset of recumbency was recorded when a dog lay down without the ability to stand. Each MRI was assessed for the presence or absence of MRI-iSOL and MRI-ICH using T2-weighted sequences. Data were analysed using the Wilcoxon rank sum test or the chi-square test. ResultsDogs with MRI-iSOL had significantly higher median sedation scores than dogs without MRI-iSOL (12 versus 5, respectively) 15 minutes after butorphanol administration (T15, p < 0.01). A greater number of dogs with MRI-ICH achieved recumbency (n = 9/10; 90%) than those without MRI-ICH (n = 20/43; 46.5%; p = 0.01). Conclusions and clinical relevanceWhen intracranial disease is suspected, the administration of butorphanol as a premedicant for anaesthesia could be used to predict the presence of MRI-iSOL and MRI-ICH. If a dog becomes recumbent or has a sedation score > 10 within 15 minutes of butorphanol administration, the animal should be treated with an anaesthesia protocol adapted to the presence of ICH.
Read full abstract