title: Cardiovascular effects of N-butylscopolammonium bromide and xylazine in horses.
abstract: BACKGROUND
  N-butylscopolammonium bromide (NBB) and xylazine are commonly used medications for the treatment of spasmodic colic and other forms of abdominal pain in horses. Both NBB and xylazine exert significant effects on the cardiovascular system and other vital systems of horses.
  
  
  OBJECTIVE
  To evaluate the effects of i.v. administration of NBB, xylazine, and the combination of NBB and xylazine on heart rate, other commonly measured physiological parameters, cardiac rhythm and blood pressure.
  
  
  METHODS
  Six mature horses of mixed breed were used. In a random cross-over design, each horse was given 0.3 mg/kg bwt of NBB i.v., 0.25 mg/kg bwt xylazine i.v., and a combination of 0.3 mg/kg bwt NBB and 0.25 mg/kg bwt xylazine. Heart rate, physiological parameters, cardiac rhythm and indirect blood pressure were recorded at timed intervals before and 60 min following administration.
  
  
  RESULTS
  Heart rate and blood pressure were significantly elevated immediately following administration of NBB or NBB with xylazine. Administration of NBB with xylazine resulted in significantly greater initial and peak blood pressure values than with NBB alone. Administration of xylazine resulted in a decrease in heart rate, with an initial increase in blood pressure followed by a decrease in blood pressure. Sinus tachycardia was seen with NBB, and NBB and xylazine administration. First and second degree atrioventricular block was identified with xylazine administration. Ventricular tachycardia was identified in one horse following NBB and xylazine administration.
  
  
  CONCLUSIONS
  Results of this study suggest that the effects of administration of NBB alone or in combination with xylazine to horses with colic, especially to those with systemic cardiovascular compromise, should be considered carefully to assess condition and predict prognosis accurately, and to avoid potential adverse effects.
authors.affiliation: Island Whirl Equine Colic Research Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida College, Gainesville, FL, USA. mortona@ufl.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Morton
authors.forename: C R
authors.initials: CR
authors.lastname: Varney
authors.forename: A B
authors.initials: AB
authors.lastname: Ekiri
authors.forename: A
authors.initials: A
authors.lastname: Grosche
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced; D001794:Blood Pressure / Q000187:drug effects*; D002086:Butylscopolammonium Bromide / Q000009:adverse effects*; D018592:Cross-Over Studies; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006734:Horse Diseases / Q000139:chemically induced*; D006736:Horses; D006993:Hypnotics and Sedatives / Q000009:adverse effects; D010276:Parasympatholytics / Q000009:adverse effects; D013997:Time Factors; D014991:Xylazine / Q000009:adverse effects*
chemical_list: D006993:Hypnotics and Sedatives; D010276:Parasympatholytics; D014991:Xylazine; D002086:Butylscopolammonium Bromide