The effect of diet and fasting on gallbladder opacification during oral cholecystography in dogs as measured by computed tomography. 
To determine the influence of diet and fasting on gallbladder opacification during oral cholecystography, 10 dogs were studied in a blind, random fashion, giving single or two consecutive doses of iopanoic acid, sodium tyropanoate, or sodium ipodate while the animals were fasting, on a normal diet, or on a low-fat diet.  Gallbladder density was determined by CT to eliminate the bias created by subjective interpretation of radiographs.  For maximum, first-dose gallbladder opacification during clinical cholecystography, iopanoic acid should be given with a meal and sodium ipodate while the patient is fasting; diet makes no difference with sodium tyropanoate.  For maximum opacification with two consecutive doses, iopanoic acid may be given with a meal or during fasting, while sodium ipodate and sodium tyropanoate should be administered during fasting.