Figure 5.

Mean CV of cortisol immunoreactivity (bar, SE) according to the number of fecal samples collected per month compared with mean CV of cortisol immunoreactivity in hair collected once monthly from 7 dogs. To compare the CVs of different fecal sampling schemes, fecal cortisol data were subsampled from each dog corresponding to 1, 2, 4, 8, or 13 samples per month. For feces, the CV for each dog was calculated from cortisol immunoreactivity averaged within months (n = 3). For hair, CV for each dog were calculated from samples collected once per month (n = 3). The P values above the error bars are from paired comparisons of CVs for cortisol immunoreactivity in hair and feces. At least 4 fecal samples per month would need to be collected to obtain a CV less than or equal to that of hair with a Bonferroni correction factor of α = 0.01 to account for the number of comparisons (that is, 5).