The Effect of Season and Breed on Hypothalamic-Pituitary-Adrenal Axis Hormones, Metabolic Hormones, and Oxidative Markers in Ponies and Horses.

Background: Endocrine function in ponies differs from horses, with seasonally increased concentrations of plasma adrenocorticotropic hormone (ACTH) and an increased risk of insulin dysregulation.

Hypothesis: (1) Season and breed differences exist in concentrations of hypothalamic-pituitary-adrenal axis and metabolic hormones; and (2) systemic oxidative status is significantly different between ponies and horses and correlates with endocrine hormones.

Animals: Thirty-four healthy Welsh ponies and 14 healthy Quarter horses.