Small Animal Rotating Intern University of Florida College of Veterinary Medicine Gainesville, FL, United States
Background: Antidiuretic hormone (ADH) is upregulated in dogs with cardiac disease, which might indicate renin-angiotensin-aldosterone system (RAAS) activation and predispose to electrolyte-free water retention. However, measurement of ADH is impractical in a clinical setting. Copeptin is co-secreted with ADH, making it a potentially clinically applicable biomarker of ADH secretion in dogs with heart disease. Hypothesis/Objectives: We hypothesized that dogs with heart disease would have higher copeptin concentrations than healthy dogs and that copeptin concentrations would positively correlate with ADH. Animals: The study population comprised 19 healthy, 20 preclinical, and 20 dogs with congestive heart failure (CHF). Methods: Prospective study. Serum chloride concentration ([Cl-]), plasma ADH, and serum copeptin were measured and compared between groups using the Kruskal-Wallis test. Agreement between ADH and copeptin was assessed with Bland-Altman analysis. Relationships between copeptin, age, ADH, serum sodium concentration, [Cl-], osmolality, and use of renin-angiotensin-aldosterone system inhibitors were explored using multivariable linear regression. Results: There were no significant differences in copeptin concentrations between healthy (median 54.9 pg/mL; range 0.5–196.1), preclinical (median 43.6 pg/mL; range 0.5–131.4), and CHF (median 60.5 pg/mL; range 0.5–997.8) dogs. Relative to ADH, copeptin showed a negative proportional bias of –87.8 pg/mL with wide limits of agreement (–421.8–246.2). Linear regression showed significant influence of age and [Cl-] on copeptin concentrations. Conclusions and Clinical Importance: Copeptin measured by ELISA does not agree with ADH concentrations in healthy dogs and dogs with cardiac disease, and should not be used as a surrogate marker. Copeptin concentrations are associated with age and [Cl-].
