title: Effect of dantrolene premedication on various cardiovascular and biochemical variables and the recovery in healthy isoflurane-anesthetized horses.
abstract: OBJECTIVE
  To determine the effect of dantrolene premedication on various cardiovascular and biochemical variables and recovery in isoflurane-anesthetized horses.
  
  
  METHODS
  6 healthy horses.
  
  
  METHODS
  Each horse was anesthetized twice with a 21- to 28-day washout period between anesthetic sessions. Food was not withheld from horses before either session. During each session, dantrolene (6 mg/kg in 2 L of water) or water (2 L) was administered via a nasogastric tube 1 hour before anesthesia was induced. Anesthesia was maintained with isoflurane for 90 minutes, during which blood gas analyses and lithium-dilution cardiac output (CO) measurements were obtained every 10 minutes. Serum creatine kinase activity was measured before and at 4, 8, and 12 hours after anesthesia.
  
  
  RESULTS
  When horses were premedicated with dantrolene, CO at 25, 35, and 45 minutes after induction of anesthesia was significantly lower than that when horses were premedicated with water after which time difficulty in obtaining valid measurements suggested a continued decrease in CO; plasma potassium concentration progressively increased during anesthesia, whereas serum creatine kinase activity remained fairly stable and within reference limits through 12 hours after anesthesia; and 2 of 6 horses developed cardiac arrhythmias that required medical intervention. The quality of anesthetic recovery was slightly better when horses were premedicated with dantrolene versus water, although the time required for recovery did not differ significantly between treatments.
  
  
  CONCLUSIONS
  Results suggested that dantrolene premedication prevented muscle damage without affecting anesthetic recovery but impaired CO and precipitated hyperkalemia and cardiac arrhythmias in healthy isoflurane-anesthetized horses.
authors: Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.
authors: Erica C
authors: EC
authors: McKenzie
authors: Stefano
authors: S
authors: Di Concetto
authors: Mark E
authors: ME
authors: Payton
authors: Ronald E
authors: RE
authors: Mandsager
authors: Matevz
authors: M
authors: Arko
mesh_terms: D000284:Administration, Oral; D000762:Anesthesia Recovery Period; D000769:Anesthesia, Inhalation / Q000662:veterinary*; D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D018592:Cross-Over Studies; D003620:Dantrolene / Q000008:administration & dosage*; D005260:Female; D006736:Horses / Q000502:physiology*; D007530:Isoflurane / Q000008:administration & dosage; D008297:Male; D009125:Muscle Relaxants, Central / Q000008:administration & dosage*; D011292:Premedication
chemical_list: D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D009125:Muscle Relaxants, Central; D007530:Isoflurane; D003620:Dantrolene