Effects of buprenorphine on cardiovascular and pulmonary function in clinically normal horses and horses with chronic obstructive pulmonary disease

Abstract

Objectives - To evaluate the cardiovascular and respiratory effects of buprenorphine administered intravenously in clinically normal horses and horses with chronic obstructive pulmonary disease (COPD). Animals - 5 clinically normal horses and 5 horses with COPD that were in partial clinical remission (period A) of were having an acute attack of airway obstruction (period B). Procedures - Pulmonary function testing, arterial blood gas analysis, and arterial blood pressure measurements were performed before and after a single intravenous bolus of buprenorphine (3 μg/kg of body weight). Respiratory rate (f), tidal volume (V(T)), expiratory-to-inspiratory time ratio (T(E)/T(I)), minute expiratory ventilation (V̇(E)), maximal change in transpulmonary pressure (ΔP(L)), dynamic compliance (C(dyn)), and pulmonary resistance (R(L)) were calculated with a pulmonary function computer. Heart rate (HR) and systolic (SABP), diastolic (DABP), and mean arterial blood pressures (MABP) were measured. Results - At baseline, COPD horses in period A had decreased C(dyn) and increased f, V̇(E), P(L), and HR, whereas COPD horses in period B had decreased T(E)/T(I) and C(dyn), arterial blood pH, and PO2, and increased f, V(E), ΔP(L), and R(L), compared with clinically normal horses. After drug administration, SABP, DABP, and MABP increased in all horses, f and V̇(E) increased in clinically normal horses, and PaO2 decreased within 60 minutes in horses with COPD. Conclusion and Clinical Relevance - Buprenorphine can induce excitement in unsedated horses or horses that do not have signs of pain, but does not seem to induce severe respiratory depression or adverse cardiovascular effects in clinically normal horses or those with COPD.