title: Determination of abomasal emptying rate in suckling calves by use of nuclear scintigraphy and acetaminophen absorption.
abstract: OBJECTIVE
  To develop nuclear scintigraphic and acetaminophen absorption methods for measuring abomasal emptying rate in suckling calves.
  
  
  METHODS
  9 male Holstein-Friesian calves < 30 days old.
  
  
  METHODS
  Calves were fed 2 L of milk replacer, fresh cow's milk, or an isoosmotic (150mM) solution of NaCl, NaHCO3, or sodium acetate containing technetium TC 99m-diethylenetriamine-pentaacetic acid (370 MBq) and acetaminophen (50 mg/kg). Right lateral scintigraphic images and venous blood samples were obtained periodically after feeding. Two power exponential equations were fitted to the scintigraphic data, and 3 pharmacokinetic models were fitted to the acetaminophen concentration-time data.
  
  
  RESULTS
  Data from 32 feedings were analyzed, with half emptying time for scintigraphic evaluation ranging from 29 to 202 minutes. Siegel's modified power exponential equation provided a better description of the scintigraphic data than did Elashoff's power exponential equation. The first derivative of Siegel's modified power exponential formula provided the best pharmacokinetic model for the acetaminophen absorption data. Time to maximal acetaminophen concentration (Tmax) provided the most accurate index of abomasal emptying rate from the acetaminophen concentration-time data.
  
  
  CONCLUSIONS
  Abomasal emptying rate is best determined in healthy suckling calves by use of Siegel's modified power exponential equation to model the scintigraphic data. Pharmacokinetic calculation of Tmax from the acetaminophen absorption curve provides an alternative method for determining abomasal emptying rate in healthy suckling calves that is accurate, inexpensive, practical, and safe. However, it is unclear whether diarrhea would alter the acetaminophen absorption curve in calves.
authors.affiliation: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802, USA.
authors.forename: Tessa S
authors.initials: TS
authors.lastname: Marshall
authors.forename: Peter D
authors.initials: PD
authors.lastname: Constable
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Crochik
authors.forename: Thomas
authors.initials: T
authors.lastname: Wittek
mesh_terms: D000018:Abomasum / Q000000981:diagnostic imaging / Q000502:physiology*; D000082:Acetaminophen / Q000097:blood / Q000493:pharmacokinetics*; D000818:Animals; D000833:Animals, Suckling / Q000502:physiology*; D002417:Cattle / Q000502:physiology*; D005746:Gastric Emptying / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007408:Intestinal Absorption / Q000502:physiology; D008297:Male; D008954:Models, Biological; D011877:Radionuclide Imaging / Q000379:methods / Q000662:veterinary*; D016284:Technetium Tc 99m Pentetate / Q000008:administration & dosage; D013997:Time Factors
chemical_list: D000082:Acetaminophen; D016284:Technetium Tc 99m Pentetate