Effects of Equine Chorionic Gonadotropin, Human Chorionic Gonadotropin, and Laparoscopic Artificial Insemination on Embryo, Endocrine, and Luteal Characteristics in the Domestic Cat1

Abstract

The effects of gonadotropin treatment and laparoscopic artificial insemination (AI) on embryo quality, serum progesterone and estradiol concentrations, and luteal progesterone content were examined in the domestic cat. These data were compared to similar historical data reported for naturally estrual, mated queens. All queens in this study (n = 32) were treated with eCG followed by 1) natural breeding (eCG-NB), 2) NB and hCG (eCG-NB-hCG), 3) NB and a sham AI procedure (eCG-NB-sham AI), or 4) hCG and actual AI (eCG-hCG-AI). Queens ovulating in response to treatment were ovariohysterectomized, and oviducts and uteri were flushed to collect embryos. Ovarian structures were recorded, corpora lutea (CL) were excised and evaluated for progesterone content, and serum was analyzed for estradiol-17beta and progesterone. Follicle and CL numbers ranged from 0 to 28 and 2 to 42 per cat, respectively, and treatment means did not differ (p > or = 0.05) among groups. Embryos were recovered from oviducts and uterine horns in all treatment groups, and recovery ranged from 60-96%. Mean embryo number per queen ranged from 8.2 +/- 2.6 to 23.2 +/- 3.8 and did not differ (p > or = 0.05) among groups. However, the proportions of unfertilized oocytes were greater (p < 0.05) for groups treated with hCG and/or artificially inseminated, and the proportion of blastocysts produced (31 of 107, 29.0%) was lower (p < 0.05) in the eCG-hCG-AI group than for any other treatment (range, 59 of 116 [50.9%] to 67 of 116 [57.8%]). Not all queens in each group produced good-quality embryos (eCG-NB, 5 of 5; eCG-NB-hCG, 5 of 8; eCG-NB-sham AI, 2 of 5; and eCG-hCG-AI, 3 of 6). Serum progesterone and estradiol-17beta, and total luteal progesterone per ovary did not differ (p > or = 0.05) among treatments. Compared to historical controls (naturally estrual, mated queens), eCG-NB queens produced > 4 times as many good-quality embryos and blastocysts. Similarly, eCG-hCG-AI-treated queens produced > 4 times the number of oocytes and embryos, although a high proportion of these were poor quality and did not develop to blastocysts. Together, these results indicate that queens treated with eCG are capable of consistently producing many good-quality embryos, at least half of which develop to blastocysts in culture. These data support the use of eCG in felids and suggest that other factors are responsible for reduced pregnancy success and small litter sizes following assisted reproduction.

Wildlife Cats Reproductive Biotechnology

“…Studies on wild cats report the use of eCG/hCG in combination, mainly to avoid the stress associated with multiple injections of FSH (Roth et al, 1997). However, the use of porcine FSH/LH determined equivalent number of oocytes compared to the established protocol for eCG/hCG used in tigers (Panthera tigris) , ocelot (Leoparuds pardalis) and tigrinas (Leopardus tigrinus) (Paz et al, 2005, demonstrating that the stress caused by daily injections did not influence the ovarian response.…”

“…Species with similar size and weight may require varying dosages, possibly because www.intechopen.com they have different sensitivities to exogenous gonadotropins (Roth et al, 1997;Swanson et al, 1996b). The nutritional status of the animal also influences the fertilization success rate.…”

Induction of ovarian activity and ovulation in an induced ovulator, the maned wolf (Chrysocyon brachyurus), using GnRH agonist and recombinant LH

“…Although these ovulatory agents have not been tested in wild canids, the combination of eCG and hCG has been commonly used to stimulate ovarian activity and induce ovulation in wild felids [6]. However, evidence suggests that these protocols can cause hyperstimulation of follicles [16] and estrogen production [17], which can ultimately be detrimental to fertilization, embryogenesis, and implantation [6]. Continued use of eCG with hCG can also result in refractoriness [18,19] and can trigger an immune response [20].…”

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

“…Assisted reproduction technologies, such as in vitro fertilization (IVF), embryo transfer (ET), and artificial insemination (AI), have tremendous potential for the captive management and conservation of genetically valuable and/or biologically endangered cat populations [Wildt et al, 1992;Roth et al, 1997]. Assisted reproduction procedures in felids require the use of exogenous gonadotropin regimens that include the administration of equine chorionic gonadotropin (eCG) or porcine follicle stimulating hormone (pFSH) to stimulate ovarian follicular development, followed by human chorionic gonadotropin (hCG) or porcine luteinizing hormone (pLH) to induce final oocyte maturation and ovulation.…”

“…Previous attempts to manipulate ovarian activity in nondomestic cats used treatment protocols that were initially developed for domestic cats [Goodrowe and Wildt, 1987;Roth et al, 1997]. Chorionic hormones, such as eCG and hCG, are often used because they have long circulatory halflives (i.e., 24-48 hr) and produce the desired ovarian response with a single injection of each hormone.…”