Abstract: Melengestrol acetate (MGA) is the most widely used contraceptive in zoo felids, but the mechanism of contraception and the pathologic effects have not been investigated. For this study, the effects of MGA on folliculogenesis were assessed, and the association of MGA with ovarian lesions was evaluated. Comparisons were made among the histopathologic findings in the ovaries from 88 captive wild felids (representing 15 species) divided into three groups: 37 currently contracepted with MGA, eight previously exposed to MGA, and 43 never contracepted. Ninety-one percent of the felids evaluated had tertiary follicles, and no differences were noted between contracepted and uncontracepted cats. Some MGA-contracepted cats also had corpora lutea indicating recent ovulation. These results indicate that folliculogenesis is not suppressed by current doses of MGA and ovulation occurred in some cats. Therefore, the contraceptive actions of MGA do not occur by suppressing folliculogenesis, and MGA-contracepted felids likely have endogenous estrogens that may confound progestin effects on the uterus. Cystic rete ovarii was the most common pathologic finding, but they were not more prevalent in MGA-contracepted cats. These findings indicate that MGA is not associated with ovarian disease, including ovarian cancer, in contrast to the uterine lesions noted in MGA-treated cats.

Abstract: The structure of the foramen ovale from 16 species representing 4 carnivore families, the Felidae, Canidae, Ursidae and Hyaenidae, was studied using the scanning electron microscope. The Felidae were represented by 9 domestic cat fetuses (Felis catus), 2 snow leopard neonates (Uncia uncia), an ocelot neonate (Leopardus pardalis), 2 lion neonates (Panthera leo), a panther neonate (Panthera pardus) and 3 tigers (Neofelis tigris), comprising 2 fetuses and a neonate. The Canidae were represented by a golden jackal neonate (Canis aureus), a newborn wolf (Canis lupus), 8 domestic dog fetuses (Canis familiaris), 3 red fox neonates (Vulpes vulpes) and a dhole neonate (Cuon alpinus). The Ursidae were represented by a brown bear neonate (Ursus arctos), a day-old grizzly bear cub (Ursus arctos horribilis), a polar bear neonate (Ursus maritimus), and 2 additional bear fetuses (species unknown). The Hyaenidae were represented by a striped hyaena neonate (Hyaena hyaena). In each species, the foramen ovale, when viewed from the terminal part of the caudal vena cava, had the appearance of a short tunnel. A thin fold of tissue, the developed remains of the embryonic septum primum, extended from the distal end of the caudal vena cava for a variable distance into the lumen of the left atrium and contributed towards the 'tunnel' appearance in all specimens. It constituted a large proportion of the tube, and its distal end was straight-edged. There was fibrous material underlying the endothelium of the flap, the apparent morphology of which suggested that it comprised cardiac muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract: The Ladakh urial (Ovis vignei vignei) is a highly endangered animal (IUCN Red List 2000) listed in the Appendix 1 of CITES and Schedule 1 of the Indian Wildlife Protection Act 1972. Its numbers had been reduced to a few hundred individuals in the 1960s and 70s through hunting for trophies and meat (Fox et al. 1991, Mallon 1983, Chundawat and Qureshi 1999, IUCN Red List 2000). However, with the protection bestowed by the IWPA 1972, and resultant decrease in hunting, the population seems to have shown a marginal increase to about 1000-1500 individuals in its range in Ladakh (Chundawat and Qureshi 1999, IUCN Red List 2000). Although the species had in the past, been able to coexist with the predominantly Buddhist society of Ladakh, the recent increase in the population of both humans and their livestock has placed immense pressures on its habitat (Shackleton 1997, Chundawat and Qureshi 1999, Raghavan and Bhatnagar 2003). This is especially important considering that the Ladakh urial habitat coincides with the areas of maximum human activity in terms of settlements, agriculture, pastoralism and development, in Ladakh (Fox et al. 1991, Chundawat and Qureshi 1999, Raghavan and Bhatnagar 2003). Increased developmental activities such as construction of roads, dams, and military bases in these areas have also increased the access to their habitat. This has consequently made the species more vulnerable to the threats of poaching and habitat destruction (Fox et al. 1991, Chundawat and Qureshi 1999, Raghavan and Bhatnagar 2002). Pressure from increased livestock grazing is one of the major threats faced by the species today (Shackleton 1997, Fox et al. 1991, Mallon 1983, IUCN Red List 2000 Chundawat and Qureshi 1999, Raghavan and Bhatnagar 2003). In the impoverished habitat provided by the Trans-Himalayas, there is great competition for the scarce resources between various animal species surviving here (Fox 1996, Mishra 2001). The presence of livestock intensifies this competition and can either force the species out of its niche (competitive exclusion) by displacing it from that area or resource, or lead to partitioning of resources between the species, spatially or temporally, for coexistence (Begon et al. 1986, Gause 1934).