Abstract
A newly developed assay for hydroxyproline (Hyp) in physiological samples was used for determining the biological variations in serum total Hyp in the beagle dog. The results showed that dietary Hyp restriction in the beagle dog results in a significant decrease in serum total Hyp over the first 24 h and that there are no obvious circadian variations in serum total Hyp concentrations in beagle dogs on dietary Hyp restriction.