Plasma ionized calcium and parathyroid hormone concentrations in horses after endurance rides.
OBJECTIVE
To evaluate changes in plasma ionized calcium (Ca2+) and parathyroid hormone (PTH) concentrations in horses competing in endurance rides.


METHODS
Longitudinal clinical study.


METHODS
28 horses.


METHODS
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
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.
Aguilera-Tejero
E
E
Department  Medicina y Cirugía Animal, Universitario de Rabanales, Córdoba, Spain.
Estepa
J C
JC
López
I
I
Bas
S
S
Garfia
B
B
Rodríguez
M
M
D000818:Animals; D002118:Calcium / Q000097:blood*; D006736:Horses / Q000097:blood* / Q000502:physiology; D008137:Longitudinal Studies; D010281:Parathyroid Hormone / Q000097:blood*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*
D010281:Parathyroid Hormone; D002118:Calcium