The Use of Hormone Antagonists to Inhibit Reproduction in the Lizard, Eublepharus macularius
J Herpe Med Surg 11[3]:4-7 Summer'01 Original Article 18 Refs

With the increase in popularity of reptiles as personal pets, there is an increasing desire to inhibit reproduction and the associated, and often times undesirable, effects. In an attempt to develop a therapeutic treatment to induce a temporary inhibition of reproduction, we implanted time-released pellets of tamoxifen, an estrogen binding inhibitor, or indomethacin, a prostaglandin synthesis inhibitor, intracoelomically into leopard geckos, Eublepharis macularius. All females treated with either tamoxifen or indomethacin (n = 6 for each group) at the onset of the reproductive season failed to show any follicular yolk deposition for the duration of the 60-day life span of the pellets, whereas 15 of 18 control females showed reproductive activity. Indomethacin treated females were completely inhibited for the entire reproductive season, but 50% of the females developed a generalized edema. Fifty percent of tamoxifen treated females showed some follicular vitellogenesis after the expiration of the pellet, but no female successfully laid a viable clutch. Treatment with tamoxifen during active vitellogenesis was ineffective at inhibiting further follicular growth or ovulation. Eight of nine tamoxifen females successfully reproduced in the year following treatment and their reproductive output (i.e., number of total clutches, number of fertile clutches) was similar to that of control females. These results suggest that tamoxifen may be a viable treatment to induce temporary reproductive inhibition in reptiles, and further study is warranted. [Abstract]