Blood Pressure and Adrenocortical Hormone Profiles in 84 Ill Dogs with Normal Post-ACTH Cortisol Concentrations

Relationship between systolic blood pressure (SBP) and adrenocortical hormones in 10 normotensive (NT) control dogs and 84 ill dogs with clinical features of hypercortisolism but normal post-adrenocorticotropic hormone (ACTH) cortisol was studied. Doppler blood pressure classified dogs as NT (<140 mm Hg), prehypertensive (PHT; 140-159 mm Hg), or hypertensive (HT; ≥160 mm Hg). Serum cortisol, progesterone, 17-hydroxyprogesterone, androstenedione, and aldosterone were measured before and 1-hr after intramuscular (IM) ACTH (250 μg/dog). Ill dogs (40 NT, 29 PHT, and 15 HT) were significantly (P ≤ .04) older, smaller, and received higher ACTH dose/kg versus controls. ACTH dose/kg was not significantly associated with post-ACTH hormone concentrations. Compared to controls, baseline hormones were significantly (P ≤ .05) higher in ill dogs, except progesterone and 17-hydroxyprogesterone in HT and aldosterone in PHT dogs; significantly higher post-ACTH 17-hydroxyprogesterone and androstenedione (P ≤ .01) in NT and PHT dogs, and aldosterone (P = .03) in HT dogs occurred. No significant differences in baseline or post-ACTH hormones existed between SBP groups. Only 3/10 controls had all hormones within reference limits. Findings suggest risk for PHT and HT in ill dogs with increased noncortisol adrenocortical hormones, and show inexplicably increased adrenocortical sex hormones in NT healthy dogs.