Short-term storage conditions do not affect canine fecal cortisol and secretory immunoglobulin A concentrations

Fecal cortisol and secretory immunoglobulin A (sIgA) are frequently used biomarkers in animal welfare, wildlife conservation, and other fields. However, these research settings often lack immediate access to a -80 °C freezer or other ultra-low temperature storage equipment. This study aims to determine whether canine fecal cortisol and sIgA concentrations remain stable over 24 h at either ambient temperature or on wet ice. Fecal samples were collected from 10 adult dogs housed in two Philadelphia area animal shelters in May and June of 2024. After aliquoting, baseline samples were frozen on dry ice within 15 minutes of defecation. Remaining aliquots were stored at ambient temperature (15–21°C) or on wet ice (4°C) for 1, 2, 4, 8, 12, or 24 hours before freezing on dry ice. Cortisol and sIgA concentrations were quantified using ELISAs and analyzed with a linear mixed effects model. No significant differences were found between time points or storage conditions. These data show that concentrations of fecal canine cortisol and sIgA remain stable if stored unfrozen for 24 hours. Immediate freezing at -80°C does not appear to be necessary for accurate quantification of these analytes. This knowledge removes logistical and regulatory barriers to conducting quality noninvasive research in animal shelter, clinical, and field settings.