Duration of sedation effects on the ACTH stimulation test in healthy dogs

Abstract

Background Sedation is frequently required in dogs for diagnostic workups and patient safety. Yet, sedation affects serum cortisol levels; butorphanol elevates cortisol, while dexmedetomidine reduces it dose dependently. Understanding the duration of sedation’s impact on cortisol concentration is important. Hypothesis/objectives To evaluate serum cortisol at time 0 and 6-hours post-administration of intravenous (IV) saline (0.5 mL), butorphanol (0.3 mg/kg) and combination of butorphanol and dexmedetomidine (0.3 mg/kg and 5 µg/kg, respectively). Additionally, to compare post-adrenocorticotrophic hormone (ACTH) cortisol concentration at 7 hours after these treatment protocols. Animals 12 healthy, castrated, colony beagles Methods Randomized, controlled, repeated-measure crossover design with a one-week washout between treatments. Serum cortisol was measured at time 0 (T0) and 6-hours (T6) post-IV administration of saline (0.5 mL), butorphanol (0.3 mg/kg), or combination butorphanol and dexmedetomidine (0.3 mg/kg and 5 µg/kg, respectively). An ACTH-stimulation test was performed at 6-hours post-treatments. Cortisol concentrations were compared with a mixed model analysis with treatment and time as fixed factors. Results Mean (± standard deviation) serum cortisol concentration was not significantly different at T0 and T6 following saline (T0 1.47 ± 1.12; T6 0.91 ± 0.29 µg/dL) butorphanol (0.9 ± 0.41; 0.95 ± 0.38 µg/dL) and combination butorphanol and dexmedetomidine (0.96 ± 0.43; 1.62 ± 0.9 µg/dL) (p = 0.29). There was no significant difference in post-ACTH cortisol for saline, butorphanol, or combination treatment (8 ± 2.25; 8.66 ± 2.26; 8.46 ± 1.83 µg/dL, respectively; p = 0.84) Conclusions and clinical importance In healthy dogs following treatment with the aforementioned protocols, cortisol concentration returns to baseline by 6 hours. An ACTH stimulation test started 6-hours post-treatment is not affected by these drug protocols. Additional studies are needed in dogs with adrenal dysfunction.