Estimation of intestinal permeability in healthy dogs using the contrast medium iohexol.
BACKGROUND
Iohexol is a nonradioactive marker that has been used successfully to test intestinal permeability in humans with inflammatory bowel disease. There is evidence in dogs that iohexol shares a similar permeability pathway as (51)chromium-EDTA, the gold standard marker.


OBJECTIVE
The objective of this study was to determine an optimal oral iohexol dosage for an intestinal permeability serum test (IPST) and to use the test to estimate intestinal permeability in healthy dogs.


METHODS
Eight clinically healthy dogs free of gastrointestinal, liver, and pancreatic disease were used in the study. Dosages of 0.25, 0.5, 1.0, 2.0, and 4.0 mL/kg of Omnipaque-350 (iohexol) were administered to 2 dogs at weekly intervals. Iohexol concentration was determined in serum samples obtained hourly for 6 hours after administration by high-performance liquid chromatography. Using the optimal dosage, iohexol was administered to 8 dogs twice, 6-36 days (mean 10 days) apart, and coefficients of variation (CVs) for iohexol concentration were calculated.


RESULTS
A dosage of 2.0 mL/kg was chosen as optimal for the IPST, based on ease of iohexol detection in serum, intestinal contrast, and clinical effects of iohexol. Following administration of this dose to healthy dogs, mean (+/-SD) serum iohexol concentrations were 8.74+/-4.38, 11.89+/-5.67, 12.40+/-5.47, 9.23+/-5.54, 7.61+/-5.13, and 5.27+/-2.67 microg/mL at 1, 2, 3, 4, 5, and 6 hours after iohexol administration, respectively. CVs between the 2 test days were 28-45%.


CONCLUSIONS
Using the iohexol dosage established in this study, the iohexol IPST was easy to perform as a marker for intestinal permeability in dogs. Further studies to establish reference intervals and evaluate the diagnostic value of the iohexol IPST in dogs with gastrointestinal disease are warranted.
Klenner
Stefanie
S
Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine, Hannover, Germany. stefanie.klenner@vetmed.unigiessen.de
Frias
Rafael
R
Coenen
Manfred
M
Failing
Klaus
K
Hewicker-Trautwein
Marion
M
Ternes
Waldemar
W
Verspohl
Jutta
J
Spillmann
Thomas
T
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D007422:Intestines / Q000502:physiology*; D007472:Iohexol / Q000008:administration & dosage / Q000494:pharmacology*; D010539:Permeability
D003287:Contrast Media; D007472:Iohexol