Hair cortisol has been demonstrated to reflect hypothalamic-pituitary-adrenal axis activity (including Cushing's disease and stress) in several species. We hypothesized that hair cortisol concentrations are increased in horses with pituitary pars intermedia dysfunction (PPID) compared with healthy adult horses and that this difference is magnified in the fall, when circulating adrenocorticotropin (ACTH) is generally the highest. Cortisol from hair collected using clippers with a #40 blade from the neck was compared between PPID horses and control horses over several months in the fall (August-December) and 1 mo in spring (May). Cortisol from hair at several sampling sites (neck, jugular furrow, sternum, and submandibular) were compared between PPID (n = 6) and control (n = 8) horses in May. Relationships between hair cortisol and ACTH were assessed in the fall. Hair cortisol when measured by weight was higher in PPID vs control horses in October and November (P ≤ 0.01) but not December (P = 0.15), May (P > 0.7), or August-September (P = 0.18). When normalized for hair length, hair cortisol was higher in PPID vs control horses in November (P = 0.0006), but not October or December (P ≥ 0.06). Hair cortisol concentrations did not differ between PPID and control horses from any collection site in May (P > 0.7). There were no consistent relationships between ACTH and hair cortisol concentrations in October, November, or December (P ≥ 0.05). These findings suggest that PPID horses have increased hair cortisol accumulation in the fall compared with control horses. Additional work is needed to clarify whether assessing cortisol per weight or per hair length is most relevant in the horse.

头发皮质醇已被证明可以反映几种物种的下丘脑-垂体-肾上腺轴活动（包括库欣病和应激）。我们假设与健康的成年马相比，患有垂体中间部功能障碍（PPID）的马的毛发皮质醇浓度会增加，并且在秋季，当循环的肾上腺皮质激素（ACTH）通常最高时，这种差异会放大。在秋季（8月至12月）的数月内和春季（5月）的1个月内，比较了PPID马和对照马在颈部使用＃40刀片的推子从头发中收集的皮质醇。5月，在PPID（n = 6）和对照组（n = 8）的马匹中比较了几个采样点（颈部，颈沟，胸骨和下颌骨）的毛发皮质醇。秋季评估了毛发皮质醇与ACTH之间的关系。10月和11月，按重量计算的毛发皮质醇在PPID中比对照马更高（P ≤0.01），但不是月（P = 0.15），月（P > 0.7），或8 - 9月（P = 0.18）。当标准化为毛发长度，毛发皮质醇PPID较高VS在十一月控制马（P = 0.0006），但不十月或腊（P ≥0.06）。五月份来自任何采集点的PPID和对照马之间的毛发皮质醇浓度没有差异（P > 0.7）。在10月，11月或12月，ACTH与头发皮质醇浓度之间没有一致的关系（P≥0.05）。这些发现表明，与对照马相比，PPID马在秋季增加了毛发皮质醇的积累。需要做更多的工作来阐明评估马的体重或每根头发的皮质醇是否最相关。