Effects of a combination of detomidine and butorphanol on respiratory function in horses with or without chronic obstructive pulmonary disease.
OBJECTIVE
To evaluate the effects of detomidine and butorphanol in combination on respiratory function in horses and to determine whether these effects are more severe in horses with pre-existing respiratory dysfunction,


METHODS
Pulmonary function testing and arterial blood gas analyses were performed before and after administration of a combination of detomidine (10 micrograms/kg of body weight, i.v.) and butorphanol (20 micrograms/kg, i.v.).


METHODS
5 horses with chronic obstructive pulmonary disease and 5 horses free of respiratory disease (controls).


METHODS
Flow rates were obtained from a pneumotachograph attached to a face mask, and esophageal pressure was measured with a catheter placed in the distal third of the esophagus. Respiratory rate, tidal volume (VT), minute ventilation (VE), maximal change in transpulmonary pressure, pulmonary resistance, and dynamic compliance were calculated by use of a pulmonary function computer. Arterial blood was collected from the transverse facial artery, and blood gas partial pressures were measured with an automated blood gas analyzer.


RESULTS
The combination of detomidine and butorphanol caused significant changes with time in respiratory rate, VT, VE, PaO2, and PaCO2. Changes with time in VT, VE, and maximal change in transpulmonary pressure were significantly different between groups.


CONCLUSIONS
The combination of detomidine and butorphanol affects respiratory function in horses, and the observed changes are affected by the presence of pre-existing respiratory dysfunction.


CONCLUSIONS
Changes in respiratory function after administration of a combination of detomidine and butorphanol are not necessarily more severe in horses with pre-existing respiratory dysfunction.
Lavoie
J P
JP
Départment de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Quebec, Canada.
Phan
S T
ST
Blais
D
D
D000403:Airway Resistance / Q000502:physiology; D000700:Analgesics / Q000494:pharmacology* / Q000627:therapeutic use; D000701:Analgesics, Opioid / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D001784:Blood Gas Analysis; D002077:Butorphanol / Q000494:pharmacology* / Q000627:therapeutic use; D002245:Carbon Dioxide / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D005260:Female; D006734:Horse Diseases / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology*; D006736:Horses / Q000097:blood / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology* / Q000627:therapeutic use; D008173:Lung Diseases, Obstructive / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D008297:Male; D010100:Oxygen / Q000032:analysis; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D012119:Respiration / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests; D013990:Tidal Volume / Q000502:physiology
D000700:Analgesics; D000701:Analgesics, Opioid; D007093:Imidazoles; D002245:Carbon Dioxide; C041255:detomidine; D002077:Butorphanol; D010100:Oxygen