The effect of 1 year of trilostane treatment on peripheral lymphocyte subsets in dogs with pituitary-dependent hyperadrenocorticism.

This study investigated the changes in lymphocyte subsets during the trilostane medication of Pituitary-dependent hyperadrenocorticism (PDH) dogs. The cortisol level and lymphocyte subsets of eight dogs with PDH were monitored 0, 1, 3, 6, 9 and 12 months after the initiation of trilostane treatment. White blood cells (WBC), lymphocytes, CD3(+) (T lymphocyte), CD4(+) (helper T lymphocyte), CD8(+) (cytotoxic T lymphocyte) and CD21(+) (B lymphocyte) cells were measured. Although the post-ACTH stimulation test cortisol level was significantly lower during trilostane treatment, changes in the CD3(+), CD4(+), CD8(+) and CD21(+) counts were not observed. Meanwhile, significant decrease was observed in WBC counts during trilostane treatment. These indicate that long-term trilostane treatment has little effect on the lymphocyte subsets in PDH dogs.