Pudu, the smallest deer of the world: 10 years of endocrine studies of Southern pudu (Pudu puda) in Chile

The first ten years of research on pudu physiology and behavior concentrated on the investigation of hormone profiles in males. Basic and seasonal levels of LH, FSH, testosterone, prolactin, IGF-1, cortisol and triiodothyronine were determined. The seasonal fluctuations of reproductive and other hormones are related to the reproductive and the antler cycles and the social rank of individual males. In addition, basal and poststimulatory levels of cortisol, growth hormone (GH), LH, FSH and testosterone were reported after ACTH and GnRH challenge tests. Most blood levels of hormones in male pudu are in the low range often less than half of hormonal levels of another small cervid, the roe deer. Pudu responds quickly to simulated stress and GnRH elicits a vigorous increase of LH and T in the dominant males. The next phase of our research is now concentrated on the reproductive physiology of the female pudu, where a delayed implantation of the embryo is suspected.