Sensitivity to Exogenous Gonadotropins for Ovulation Induction and Laparoscopic Artificial Insemination in the Cheetah and Clouded Leopard1

Abstract

Ovarian sensitivity to exogenous gonadotropins was assessed in the cheetah (Acinonyx jubatus) and clouded leopard (Neofelis nebulosa) to help optimize artificial insemination (AI). Eighteen female cheetahs were used on 29 occasions and were given i.m. injections of 100, 200, or 400 IU eCG and 100 or 250 IU hCG 80 h later. Twenty-three female clouded leopards were treated i.m. on 27 occasions with 25, 50, 75, 100, 200, or 400 IU eCG followed 80 h later with 75, 140, or 280 IU hCG. Ovaries were examined laparoscopically at 43-48 h after hCG in cheetahs and 39-50 h in clouded leopards. All gonadotropin dosages stimulated ovarian activity in both species, but ovulation success and corpus luteum (CL) morphology varied (p < 0.05) with treatment. For both species, the highest and intermediate eCG dosages resulted in ovulation in a high proportion (72-100%) of females. The lowest eCG dosage, although capable of stimulating follicular development, compromised ovulation and resulted in few (< 26%) postovulatory females. For each species, small CL (2-4-mm diameter) were observed with the highest and lowest eCG dosage, and large CL (5-8-mm diameter) were associated with intermediate eCG dosages. Aged CL (10-12 mm diameter) were observed in 4 of 23 (17.4%) clouded leopards with no prior male exposure, indicating occasional spontaneous ovulation. Nineteen laparoscopic intrauterine AI procedures were performed in eCG/hCG-treated postovulatory cheetahs. Eighteen AI procedures were conducted in eCG/hCG-treated postovulatory clouded leopards. Six of the 13 cheetahs (46%), all in the 200-IU eCG/100-IU hCG group, became pregnant, in contrast to none of the clouded leopards. This study has revealed differences in ovarian activity in two wild felid species as a result of changes in exogenous gonadotropin dosage. Because of this dose-effect response, this comparative approach is necessary to identify a gonadotropin regimen that can mimic "normalcy." Even then, the relatively high AI success in the cheetah compared to the clouded leopard suggests that factors other than ovarian response can dictate the efficiency of assisted reproduction in this taxon.

Approaches and efficacy of artificial insemination in felids and mustelids

“…In contrast, it is recognized that a cheetah can become pregnant after a single mating, despite the male ejaculating mostly malformed spermatozoa [34]. Furthermore, AI-derived pregnancies also have resulted in this species from inseminating comparative low sperm density inseminates comprised of >70% abnormally shaped cells (see below) [34,50]. Thus, the threshold for an adverse effect of teratospermia on conception is relatively high or perhaps the cheetah is comparatively reproductively 'efficient', requiring few total spermatozoa (even in the face of many malformed cells) to achieve successful fertilization.…”

“…Hormonal monitoring also has been essential for titrating eCG/hCG dosages to avoid ovarian hyperfollicular stimulation and excessive circulating estrogen production (e.g., cheetah and tiger) [23,24,34]. In most cases, the confidence in a specific eCG/hCG regimen can be determined by parallel (or historic) profiling of gonadal endocrine patterns in naturally estrual and/or copulating conspecifics.…”

“…The few attempts to produce pregnancies in the naturally mating Florida panther held in captivity met with failure [49]. In contrast, it is recognized that a cheetah can become pregnant after a single mating, despite the male ejaculating mostly malformed spermatozoa [34]. Furthermore, AI-derived pregnancies also have resulted in this species from inseminating comparative low sperm density inseminates comprised of >70% abnormally shaped cells (see below) [34,50].…”

“…Laparoscopy also has been used extensively for characterizing felid reproductive tract anatomy and ovarian events, including documenting follicular development, presence of fresh (corpora hemorrhagica, CH) and mature corpora lutea (CL) and the effectiveness of various gonadotropin therapies [9,10]. This laparoscopic AI technique was utilized initially in the domestic cat and then successfully extrapolated to the cheetah (Table 2) [34,63].…”

“…Similar results for cheetahs are depicted in Table 3. Three females failed to ovulate when anesthesia and insemination were conducted before ovulation, whereas pregnancies were established in females anesthetized and inseminated after ovulation (Table 3) [34,50].…”