Iohexol-based measurement of intestinal permeability in birds

Abstract

Background: Iohexol has been successfully used as a marker to assess intestinal permeability in humans and various other mammals. The objective of this study was to evaluate the use of oral iohexol as an intestinal permeability marker in four anatomically and nutritionally diverse bird species. Methods: Three dosages (1 ml/kg, 2 ml/kg, 4 ml/kg) of iohexol (755 mg/ml) were administered orally to each six clinically healthy pigeons and chickens at two-week intervals. Iohexol plasma concentration was determined 45, 90 and 180 minutes after administration. A comparative study was performed by administering iohexol twice to each six clinically healthy cockatiels and falcons, and determining iohexol plasma concentration at 45 or 90 minutes after administration. Results: The recommended iohexol dosage for permeability testing in birds was determined to be 1 ml/kg. Median plasma iohexol concentrations were 27.77 µg/ml in pigeons, 12.97 µg/ml in chickens, 14.24 µg/ml in cockatiels, and 47.81 µg/ml in falcons, 45 minutes after this dosage was administered. At 90 minutes after administration, median plasma iohexol concentrations were 40.68 µg/ml in pigeons, 21.59 µg/ml in chickens, 32.03 µg/ml in cockatiels, and 55.96 µg/ml in falcons. Conclusions and clinical relevance: Oral iohexol was a safe and feasible marker for intestinal permeability assessment in birds. Further investigations are warranted to establish species-specific reference intervals in larger numbers of healthy birds, and to examine the use of iohexol as a permeability marker in birds with disorders associated with altered intestinal permeability.