Endocrine and ultrasound evaluation of a non-cycling African elephant: Identification of an ovarian follicular cyst
Publication Type: |
Journal Article |
Year of Publication: |
1999 |
Authors: |
Janine L. Brown, Thomas B. Hildebrandt, William Theison, Donald L. Neiffer |
Publication/Journal: |
Zoo Biology |
Publisher: |
Inc., John Wiley & Sons |
Keywords: |
follicle, gonadotropin-releasing hormone, human chorionic gonadotropin, loxodonta africana, luteinizing-hormone, ovarian cyst, ovary, progesterone, ultrasonography |
ISBN: |
1098-2361 |
Abstract:
The reproductive rate of captive African elephants is low because of logistical difficulties associated with transporting animals for breeding, the danger of maintaining bulls and medical or physiological problems. There also is growing evidence that a significant number of mature female elephants are not experiencing normal estrous cycles. The case described in this report involves the diagnosis and attempted treatment of an ovarian follicular cyst in an African elephant at the Pittsburgh Zoo. On the basis of serum progesterone analysis, the female exhibited regular ovarian cycles from July 1993 through March 1994, but from November 1994 to the present has not shown any evidence of reproductive cyclicity. In April 1996, a large follicular structure was identified on the right ovary using transrectal ultrasound. In an attempt to luteinize the cyst, 500 μg gonadotropin-releasing hormone (GnRH) was administered intravenously in October 1996, which stimulated a modest increase in serum luteinizing hormone (LH) (approximately twofold over baseline), but no resumption of ovarian activity. The elephant was treated again 5 months later with a higher dose of GnRH (5 mg, i.v.) with the same results. An ultrasound evaluation in July 1997 indicated the structure was still present. In October 1997, the female was given human chorionic gonadotropin (hCG; 10,000 IU, i.m.), which induced estrus and breeding, but no ovulation or luteinization of the cyst, and she remains acyclic. These results suggest that conventional methods developed in other species for treating ovarian follicular cysts may not necessarily be effective in the elephant. It is also important that reproductive age females be monitored via continuous progesterone analysis and occasional reproductive tract ultrasound evaluations to understand better the etiology of ovarian dysfunction so that effective treatments can be developed to induce consistent ovarian activity.