Ovarian and immunological responses to alternating exogenous gonadotropin regimens in the ocelot (Leopardus pardalis) and tigrina (Leopardus tigrinus)

Abstract

Exogenous gonadotropins frequently are used to stimulate ovarian follicular growth and ovulation in mammalian species, including felids. However, repeated exogenous gonadotropin treatment can result in decreased ovarian responsiveness due to antibody formation. In this study, our objectives were to assess the effectiveness of alternating gonadotropin regimens on ovarian responses in ocelots and tigrinas, and investigate the humoral immune responses to these gonadotropins in each species. Females were treated four to six times with alternating equine chorionic gonadotropin (eCG)/human chorionic gonadotropin (hCG) and porcine follicle stimulating hormone (pFSH)/luteinizing hormone (pLH) regimens at 4-month intervals. With each treatment, the females were evaluated laparoscopically to assess ovarian follicular development and recover oocytes from mature follicles. Blood was collected before each treatment and at laparoscopy. Overall, the ocelots averaged more (Po0.05) follicles and corpus luteum (CL) (6.870.8; mean7SEM) per stimulation than the tigrinas (2.370.4), but the percentage of mature oocytes (mean range ¼ 54-55%) did not differ (Po0.05). Within species, both gonadotropin regimens were equally effective (P40.05) in inducing follicular growth and oocyte maturation. The total number of ovarian structures and oocyte maturation percentages did not decrease (Po0.05) in either species with sequential stimulations. Although the percentage of blood samples containing anti-gonadotropin immunoglobulins increased (Po0.05) with sequential treatment, the presence of positive titers did not cause a decrease (Po0.05) in ovarian responsiveness. In summary, the female ocelots and tigrinas continued to respond to these alternating ovarian stimulation protocols after repeated use, despite the formation of anti-gonadotropin antibodies in some of the females. These findings suggest that the use of alternating gonadotropin regimens may permit more intensive reproductive management of these endangered cat species for conservation. Zoo Biol 24: 247-260, 2005.

The use of altrenogest to avoid hyperestrogenism after eCG-hCG ovulation induction in southern tigrina (Leopardus guttulus)

“…In the first trial, eCG (200 IU) and hCG (150 IU) were administered intramuscularly 80 to 84 hours (mean: 82 AE 2 hours) apart as suggested by previous studies [16]. The second trial was conducted 4 months later to avoid antigonadotropin immunocomplex formation [12] and involved oral administration of the progestin altrenogest (Regumate, Intervet) over a 14-day period before eCG-hCG treatment, which were administered intramuscularly 80 to 103 hours (females 1909 and 1707 received eCG-hCG 103 hours after eCG, whereas the other four females received hCG with a mean of 82 AE 2 hours) apart. Time between the last altrenogest dose and eCG-hCG treatment was between 48 and 72 hours.…”

“…Despite over 15 years of research on mechanisms involving wild felid ovarian activity [3,[8][9][10][11][12][13], there are still problems with inducing normal ovarian response using exogenous gonadotropins [14], with poor responses being attributed to low pregnancy rates [3,5,14]. The most common problem associated with gonadotropin ovulation induction is ovarian hyperstimulation, which leads to an overproduction of follicles, high levels of estrogen, premature or excessive progesterone release, and sometimes premature luteolysis [13,14].…”