ABSTRACT Background Serum copeptin (sCoP) is used as a surrogate for plasma arginine vasopressin (pAVP) measurement in humans. Objective To measure pAVP and sCoP at rest and after osmotic‐ and non‐osmotic stimulation testing in dogs. Animals Eight young castrated/spayed healthy research Beagles, eight young intact dogs, and eight old neutered healthy client‐owned dogs. Methods In this prospective longitudinal study, pAVP and sCoP were measured under iso‐(baseline), hypo‐(water load followed by intravenous administration of desmopressin WLT), and hyper‐(water deprivation test WDT) osmolar conditions assessed by measured plasma osmolality (pOsm (m) ), and after administration of arginine (AST), IV, and Bovril (BST), PO. The fraction of change ( F ) in a variable y (e.g., pAVP) between baseline ( T 0 ) and a timepoint X ( T X ) during testing was defined as Fy = y ( T X ) – y ( T 0 )/ y ( T 0 ). Results Baseline sCoP had wide inter‐individual variations. Mean range FpAVP and FsCoP at the end of WDT were +110% +80; +142 and +18% +0.4; +38 compared to baseline, respectively. Mean range FpAVP after water load and FsCoP after water load followed by desmopressin administration were −22% −48; −0.5 and −29% −39; −14 compared to baseline, respectively. Both FpAVP and FsCoP were strongly correlated to FpOsm (m) ( r = +0.76, p = 0.004; r = +0.78, p = 0.002; respectively). When sCoP was measured at T 4h instead of T 2h during WLT, to reflect its longer half‐life reported in humans, the correlation between FpAVP P800 and FsCoP became excellent ( r = +0.90, p < 0.001). No stimulation of sCoP secretion occurred during AST or BST. Conclusion and Clinical Importance Serum CoP could be used as a surrogate for pAVP measurement in healthy dogs.
Paulin et al. (Mon,) studied this question.
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