Validation of salivary oxytocin and vasopressin as biomarkers in domestic dogs

•We validated immunoassays for measuring oxytocin (OT) and vasopressin (AVP) in dog saliva.•OT and AVP were present in dog saliva and detectable by ELISA and HPLC–MS.•Assays yielded good parallelism and accuracy, both with and without extraction.•Dams exhibited an increase in both salivary and plasma OT when nursing their litters Oxytocin (OT) and Vasopressin (AVP) are phylogenetically conserved neuropeptides with effects on social behavior, cognition and stress responses. Although OT and AVP are most commonly measured in blood, urine and cerebrospinal fluid (CSF), these approaches present an array of challenges including concerns related to the invasiveness of sample collection, the potential for matrix interference in immunoassays, and whether samples can be collected at precise time points to assess event-linked endocrine responses. We validated enzyme-linked immunosorbent assays (ELISAs) for the measurement of salivary OT and AVP in domestic dogs. Both OT and AVP were present in dog saliva and detectable by ELISA and high performance liquid chromatography – mass spectrometry (HPLC–MS). OT concentrations in dog saliva were much higher than those typically detected in humans. OT concentrations in the same samples analyzed with and without sample extraction were highly correlated, but this was not true for AVP. ELISA validation studies revealed good accuracy and parallelism, both with and without solid phase extraction. Collection of salivary samples with different synthetic swabs, or following salivary stimulation or the consumption of food led to variance in results. However, samples collected from the same dogs using different techniques tended to be positively correlated. We detected concurrent elevations in salivary and plasma OT during nursing. There are currently no other validated methods for measuring OT/AVP in dog saliva. OT and AVP are present in dog saliva, and ELISAs for their detection are methodologically valid.