Cardiac troponin I concentrations following medetomidine-butorphanol sedation in dogs.

OBJECTIVE

To evaluate the effect of medetomidine-butorphanol sedation on serum cardiac troponin I (cTnI) concentration, a marker of myocardial ischemia and injury, in healthy dogs undergoing pre-surgical radiographs for orthopedic procedures.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Twenty client-owned dogs with no history of cardiac disease.

METHODS

Dogs were evaluated for pre-existing cardiac disease with electrocardiogram (ECG), noninvasive blood pressure and echocardiogram. Sedation was achieved using a combination of medetomidine (10 microg kg(-1)) and butorphanol (0.2 mg kg(-1)) intravenously. Blood pressure, heart rate and ECG were serially recorded throughout the duration of sedation. Serum cTnI concentration was measured at baseline and 6, 18, and 24-hours post-sedation.

RESULTS

Following administration of medetomidine and butorphanol, all dogs were adequately sedated for radiographs and had a decreased heart rate and increased diastolic blood pressure. Arrhythmias associated with increased parasympathetic tone occurred, including a sinus arrhythmia further characterized as a sinus bigeminy in 17 of the dogs. Serum cTnI was undetectable at all time points in all but three dogs. Two of the three dogs had a detectable concentration of cTnI at all time points measured, including prior to sedation. Only one of the two dogs had a cTnI concentration above the normal reference interval. The dogs that exhibited detectable cTnI had no significant difference in signalment, heart rate, blood pressure, or lactate concentration as compared to those with undetectable cTnI.

CONCLUSIONS AND CLINICAL RELEVANCE

Sedation with medetomidine and butorphanol had predictable cardiovascular effects including bradycardia, an increase in arterial blood pressure, and arrhythmias in apparently healthy dogs requiring radiographs for orthopedic injuries, but did not induce significant increases in serum cTnI concentration following the drug doses used in this study.