Antidiuretic hormone concentrations in dogs with heart disease and relationship to serum chloride

Non-osmotic antidiuretic hormone (ADH) release promotes electrolyte-free water retention in dogs with congestive heart failure (CHF), contributing to low electrolyte concentrations. We hypothesized that dogs with CHF would have higher ADH concentrations than healthy dogs and dogs with preclinical heart disease, and that ADH concentrations would positively correlate to the amount of chloride [Cl^-] correction but not serum osmolality.

The study population comprised 20 healthy, 20 preclinical, and 20 CHF dogs. Serum electrolytes, serum osmolality, and plasma ADH were measured and compared between groups using the Kruskal-Wallis test. Relationships between ADH and electrolytes, the amount of [Cl^-] correction, osmolality, and the use of amlodipine and renin-angiotensin-aldosterone system inhibitors were explored with multiple linear regression.

Preclinical (median 6.5 pg/mL; range 1.8 pg/mL-33.8 pg/mL) and CHF (6.7 pg/mL; range 2.0 pg/mL-28.1 pg/mL) dogs had higher ADH concentrations than healthy dogs (median 3.4 pg/mL; range 0.1 pg/mL-6.2 pg/mL) (P=0.004) but there was no difference between preclinical and CHF dogs. Serum ADH was inversely correlated with [Cl^-] (P=0.026, r_s = -0.287) and c[Cl^-] (P=0.008, r_s = -0.338). Amlodipine use and [Cl^-] predicted ADH after controlling for age, weight, use of renin-angiotensin aldosterone inhibitors, and osmolality. There was no significant relationship between ADH and the amount of [Cl^-] correction, osmolality, or serum sodium.

The inverse relationship between ADH and serum [Cl^-] and the positive relationship with amlodipine use suggests neurohormonal stimulation as a common mechanism. Uncoupling of ADH from osmolality and serum sodium is consistent with non-osmotic release, which was present even in dogs with preclinical heart disease.

Antidiuretic hormone was elevated in dogs with heart disease but was not a unique feature of advanced heart disease.