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- Author or Editor: Bartolomé Garfia x
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Objective—To compare the adrenocortical response of healthy dogs to a commonly used dose of a nonadsorbed tetracosactide product (tetracosactide) with responses to 2 doses of a depot formulation of tetracosactide (depot tetracosactide).
Procedures—Dogs were randomly assigned to receive tetracosactide (5 mg/kg, IV) or depot tetracosactide (250 μg, IM, or 5 μg/kg, IM). Dogs received each treatment once with a 2-week interval between treatments. Blood samples were assayed for cortisol, progesterone, 17-hydroxyprogesterone, androstenedione, and estradiol concentrations.
Results—Serum cortisol concentrations were significantly higher than the preadministration (baseline) concentrations for all treatments 60 minutes after administration of ACTH. Peak cortisol concentration was detected 180 minutes after IM administration of 250 μg of the depot tetracosactide. Serum concentrations of progesterone, 17-hydroxyprogesterone, and androstenedione did not differ significantly from baseline concentrations after stimulation with the 5 μg/kg dose of depot tetracosactide. Adrenal gland progesterone response was significantly higher than baseline concentrations at 60 minutes after administration of the 250-μg dose of depot tetracosactide, and the 17-hydroxyprogesterone and androstenedione responses were significantly higher than baseline concentrations at 120 minutes. Compared with the response to tetracosactide, adrenocortical response was higher and more sustained following administration of the depot tetracosactide, except for androstenedione concentration, which had a nonsignificant response.
Conclusions and Clinical Relevance—Except for androstenedione concentrations, a high dose of the depot tetracosactide (250 μg, IM) induced an adrenocortical response similar to that after administration of tetracosactide. Thus, depot tetracosactide may represent an alternative to the nonadsorbed tetracosactide product.
Objective—To evaluate changes in plasma ionized calcium (Ca2+) and parathyroid hormone (PTH) concentrations in horses competing in endurance rides.
Design—Longitudinal clinical study.
Procedure—Venous blood samples were obtained from horses before and after racing 80 km. Plasma pH and concentrations of Ca2+, PTH, inorganic phosphorus, albumin, lactate, and magnesium were measured.
Results—Overall, a significant decrease in mean (± SD) plasma Ca2+ concentration (from 6.44 ± 0.42 to 5.64 ± 0.42 mg/dl) and a significant increase in plasma PTH concentration (from 49.9 ± 30.1 to 148.1 ± 183.0 pg/ml) were found after exercise. Exercise also resulted in significant increases in plasma inorganic phosphorus, albumin, and lactate concentrations. No changes in plasma magnesium concentration or pH were detected after exercise. Plasma PTH concentration was not increased after exercise in 8 horses; in these horses, plasma PTH concentration decreased from 58.2 ± 26.3 to 27.4 ± 22.4 pg/ml, although plasma Ca2+ concentration was also decreased.
Conclusions and Clinical Relevance—Plasma Ca2+ concentration was decreased after racing for 80 km, compared with values obtained before racing. In most horses, an increase in plasma PTH concentration that was commensurate with the decrease in plasma Ca2+ was detected; however, some horses had decreased plasma PTH concentrations. (J Am Vet Med Assoc 2001;219:488–490)