The effects of anesthetic drug choice on heart rate variability in dogs

Abstract

Objective: The objective of this study was to assess the effects of anesthetic drugs on heart rate (HR) and heart rate variability (HRV) in dogs. Materials and Methods: Twelve healthy client-owned dogs of various breeds, including five females and seven males were used for elective surgery in this study. The dogs were pre-medicated with four protocols; (1) alfaxalone [at 3 mg/kg body weight (bwt)], (2) zolazepam + tiletamine (Zoletil) (at 5 mg/kg bwt), (3) diazepam (at 0.3 mg/kg bwt) + ketamine (at 5 mg/kg bwt), and (4) diazepam (at 0.3 mg/kg bwt) + propofol (at 5 mg/kg bwt). The HR and HRV of 12 dogs were recorded 20 min before and after the administration of the anesthetic drugs. Doppler was used to obtain systolic, diastolic, and mean blood pressures. Results: After anesthetic drug administration, the dogs pre-medicated and inducted with alfaxalone had the lowest HR values as compared with those of other protocols. The HRV low frequency and high frequency power ratio decreased in the dogs pre-medicated and intubated with alfaxalone. Conclusion: This study demonstrates that alfaxalone preserves the cardiovascular function; and hence, is considered as safe to use for the surgical applicability in dogs.

Clinical review of the pharmacological and anaesthetic effects of alfaxalone in dogs

“…In comparison with propofol, tiletamine-zolazepam and ketamine-diazepam, no significant differences in HR and ABP were found using alfaxalone (Maney et al 2013, Pattanapon et al 2018, Hampton et al 2019a). However, a further decrease in HR and ABP was described in the propofol group (Pattanapon et al 2018).…”

“…After alfaxalone administration, a positive chronotropic effect might represent a compensatory change to maintain Qt and ABP following a decrease of SVR (Morgaz Rodríguez et al 2012, Pinelas et al 2014, Seo et al 2015, Hampton et al 2019a). However, a negative chronotropic effect was recorded in one study assessing the HR variability of different anaesthetic agents; nevertheless, Qt was well maintained (Pattanapon et al 2018).…”

“…In non-sedated healthy dogs, the administration of clinical doses of alfaxalone had minimal cardiovascular effects: Qt was maintained or improved, arterial blood pressure (ABP) was maintained or decreased but remaining within normal limits, systemic vascular resistance (SVR) and afterload were maintained or decreased (Muir et al 2008, Morgaz Rodríguez et al 2012, Maney et al 2013, Seo et al 2015, Pattanapon et al 2018, Hampton et al 2019a). On the contrary, the administration of doses >6 mg/kg caused a dose-dependent decrease in Qt and ABP possibly related to a negative inotropic effect, while HR temporarily increased (Muir et al 2008).…”

“…However, a negative chronotropic effect was recorded in one study assessing the HR variability of different anaesthetic agents; nevertheless, Qt was well maintained (Pattanapon et al . 2018).…”

“…However, a further decrease in HR and ABP was described in the propofol group (Pattanapon et al . 2018).…”