EFFECTS OF BUPRENORPHINE ON CARDIOVASCULAR AND PULMONARY-FUNCTION IN CLINICALLY NORMAL HORSES AND HORSES WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Objectives-To evaluate the cardiovascular and respiratory effects of b uprenorphine administered intravenously in clinically normal horses an d horses with chronic obstructive pulmonary disease (COPD). Animals-5 clinically normal horses and 5 horses with COPD that were in partial c linical remission (period A) or were having an acute attack of airway obstruction (period B). Procedures-Pulmonary function testing, arteria l blood gas analysis, and arterial blood pressure measurements were pe rformed before and after a single intravenous bolus of buprenorphine ( 3 mu g/kg of body weight). Respiratory rate (f), tidal volume (V-T), e xpiratory-to-inspiratory time ratio (T-E/T-I) minute expiratory ventil ation ((V)over dot(E)), maximal change in transpulmonary pressure (Del ta P-L), dynamic compliance (C-dyn) and pulmonary resistance (R-L) wer e calculated with a pulmonary function computer. Heart rate (HR) and s ystolic (SABP), diastolic (DABP), and mean arterial blood pressures (M ABP) were measured. Results-At baseline, COPD horses in period A had d ecreased C-dyn and increased f, (V)over dot(E), P-L, and HR, whereas C OPD horses in period B had decreased T-E/T-I and C-dyn, arterial blood pH, and PO2, and increased f, (V)over dot(E), Delta P-L, and R-L, com pared with clinically normal horses. After drug administration, SABP, DABP, and MABP increased in all horses, f and (V)over dot(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 w ith COPD.