Effects of anesthesia, surgery, and intravenous administration of fluids on plasma antidiuretic hormone concentrations in healthy dogs

Objective-To evaluate effects of anesthesia, surgery, and intravenous admin istration of fluids on plasma concentrations of antidiuretic hormone (ADH), concentration of total solids (TS), PCV, arterial blood pressure (BP), pla sma osmolality, and urine output in healthy dogs. Animals-22 healthy Beagles. Procedure-11 dogs did not receive fluids, and 11 received 20 mi of lactated Ringer's solution/kg of body weight/h. Plasma ADH adn TS concentrations, P CV, osmolality, and arterial BP were measured before anesthesia (T-0) and a fter administration of preanesthetic agents (T-1), induction of anesthesia (T-2), and 1 and 2 hours of surgery (T-3 and T-4, respectively). Urine outp ut was measured at T-3 and T-4. Results-ADH concentrations increased at T-1, T-3, and T-4, compared with co ncentrations at T-0. Concentration of TS and PCV decreased at all times aft er administration of preanesthetic drugs. Plasma ADH concentration was less at T3 in dogs that received fluids, compared with those that did not. Bloo d pressure did not differ between groups, and osmolality did not increase > 1% from To value at any time. At T-4, rate of urine production was less in dogs that did not receive fluids, compared with those that did. Conclusions and Clinical Relevance-Plasma ADH concentration increased and P CV and TS concentration decreased in response to anesthesia and surgery. In travenous administration of fluids resulted in increased urine output but h ad no effect on ADH concentration or arterial BP. The causes and effects of increased plasma ADH concentrations may affect efficacious administration of fluids during the perioperative period in dogs.