title: Hemodynamic effects in dogs after intramuscular administration of a combination of dexmedetomidine-butorphanol-tiletamine-zolazepam or dexmedetomidine-butorphanol-ketamine.
abstract: OBJECTIVE
  To evaluate hemodynamic effects in dogs after IM administration of dexmedetomidine (7.5 μg/kg, butorphanol (0.15 mg/kg), and tiletamine-zolazepam (3 mg/kg [DBTZ]) or dexmedetomidine (15 μg/kg), butorphanol (0.3 mg/kg), and ketamine (3 mg/kg [DBK]).
  
  
  METHODS
  5 healthy adult mixed-breed dogs.
  
  
  METHODS
  Each dog received DBTZ and DBK in a randomized crossover study with a 48-hour interval between treatments. Anesthesia was induced and maintained with sevoflurane in 100% oxygen while instrumentation with Swan-Ganz and arterial catheters was performed. Following instrumentation, hemodynamic measurements were recorded at 3.54% (1.5 times the minimum alveolar concentration) sevoflurane; then sevoflurane administration was discontinued, and dogs were allowed to recover. Six hours after cessation of sevoflurane administration, baseline hemodynamic measurements were recorded, each dog was given an IM injection of DBTZ or DBK, and hemodynamic measurements were obtained at predetermined intervals for 70 minutes.
  
  
  RESULTS
  DBTZ and DBK induced hypoventilation (Paco2, approx 60 to 70 mm Hg), respiratory acidosis (pH, approx 7.2), hypertension (mean arterial blood pressure, approx 115 to 174 mm Hg), increases in systemic vascular resistance, and reflex bradycardia. Cardiac output, oxygen delivery, and oxygen consumption following DBTZ or DBK administration were similar to those following sevoflurane administration to achieve a surgical plane of anesthesia. Blood l-lactate concentrations remained within the reference range at all times for all protocols.
  
  
  CONCLUSIONS
  In healthy dogs, both DBTZ and DBK maintained oxygen delivery and oxygen consumption to tissues and blood lactate concentrations within the reference range. However, ventilation should be carefully monitored and assisted when necessary to prevent hypoventilation.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Krimins
authors.forename: Jeff C
authors.initials: JC
authors.lastname: Ko
authors.forename: Ann B
authors.initials: AB
authors.lastname: Weil
authors.forename: Mark E
authors.initials: ME
authors.lastname: Payton
authors.forename: Peter D
authors.initials: PD
authors.lastname: Constable
mesh_terms: D000698:Analgesia / Q000379:methods / Q000662:veterinary*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001919:Bradycardia / Q000662:veterinary; D002077:Butorphanol / Q000008:administration & dosage*; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D020927:Dexmedetomidine / Q000008:administration & dosage*; D004285:Dogs / Q000502:physiology*; D004338:Drug Combinations; D005260:Female; D007273:Injections, Intramuscular / Q000662:veterinary; D007649:Ketamine / Q000008:administration & dosage*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D012119:Respiration / Q000187:drug effects; D013992:Tiletamine / Q000008:administration & dosage*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D015041:Zolazepam / Q000008:administration & dosage*
chemical_list: D004338:Drug Combinations; C006131:tiletamine, zolazepam drug combination; D013992:Tiletamine; D019344:Lactic Acid; D020927:Dexmedetomidine; D007649:Ketamine; D015041:Zolazepam; D002077:Butorphanol