Cheryl S. Asa

Chemical scent constituents in urine of wolf (Canis lupus) and their dependence on reproductive hormones

The volatile components of castrated male and ovariectomized female wolf urine were investigated and correlated with the administration of testosterone or estradiol and progesterone. The results indicate that testosterone induces in the castrated male the formation of some compounds typically associated with the intact male, while reducing the levels of some compounds associated with castrated male and female. The production of some of the “male” compounds was also induced in the ovariectomized female, although at lower levels. Changes in hormone levels during treatment of females are reflected in the composition of the urinary volatiles. Consequently, many of these compounds could be used to communicate gender as well as reproductive status.

Chemical investigations of wolf (Canis lupus) anal-sac secretion in relation to breeding season.

The volatile constituents of wolf anal-sac secretions were examined via capillary gas chromatography and compared among intact males, females, castrate males, ovariectomized females, and anosmic and pinealectomized males and females. Some chemical compounds were deemed significantly different (t test, 95% confidence level) among the groups both during and outside of the mating season, implying that the volatile components of anal-sac secretion can be used to communicate information regarding gender or endocrine state. As a result of treating the anal sac with antibiotics, some of these compounds, including 1-octen-3-ol and indole, were implicated as being products of microbial action. In addition, short-chain carboxylic acids were investigated and essentially no significant variations were seen among the groups.

Deposition of Anal-Sac Secretions by Captive Wolves (Canis lupus)

Deposition of anal-sac secretions by captive wolves was investigated by a labelling technique using protein-bound iodine125 and food dye. Wolves deposited secretions on some but not all scats. Adult males, especially the alpha male, deposited anal-sac secretions more frequently while defecating than did females or juveniles. Secretions sometimes also were deposited independently of defecation, suggesting a dual role in communication by these substances.

Use it or lose it: Characterization, implications, and mitigation of female infertility in captive wildlife

Zoos and other ex situ wildlife institutions can play an important role in species conservation by maintaining populations for education and research, as sources for potential re-introduction or reinforcement, and as ambassadors for financial support of in situ conservation. However, many regional zoo associations are realizing that current captive populations are unsustainable, with many programs failing to meet demographic and genetic goals to ensure long-term viability. Constraints on population size due to limited space often mandate delayed and/or less frequent breeding, but for females of many species this can have profound effects on fertility. A retrospective analysis combined with published literature and reliable anecdotal reports reveals that, when females are housed in a non-breeding situation for extended periods of time, reproductive changes that negatively impact fertility have occurred in multiple species, including canids, elephants, white rhinoceros, Sebas bats, wildebeest, stingrays, and some felid species. Competing space needs and changing interest in taxa for exhibits over time compound the problem. Counter strategies to breed early and often have their own demographic and genetic consequences as well as logistical and political implications. Strategies to mitigate the sustainability crisis in these taxa might include a mixed strategy in which young, genetically valuable females are bred earlier and at more regular intervals to ensure reproductive success, in combination with the judicious use of available tools to manage the number of offspring produced, including contraception and culling. An understanding of the issues at stake is the first step towards developing management strategies for sustainable populations.

Estrous Cycles, Copulation, and Pregnancy in the Fennec Fox (Vulpes Zerda)

Abstract Characteristics of estrus, mating, and pregnancy were studied in captive fennec foxes. The monestrous cycles had mean intervals of 9.9 (±1.2) months, whether or not pups survived to weaning. Proestrus, judged by vulval swelling, began 6.5 (±0.7) days before estrus and was not accompanied by sanguineous discharge. Percentage cornified epithelial cells in vaginal smears increased at the time of estrus. In 8 of 10 estrous periods, a single mating followed by an extremely long copulatory lock (mean 1 h 58 min) was observed during continuous video monitoring. In the other two cycles, copulation occurred 2 and 3 times. Patterns of both fecal and serum estradiol and progesterone concentrations during estrous cycles were similar to those reported for other canids.

EVIDENCE FOR INDUCED ESTRUS OR OVULATION IN A CANID, THE ISLAND FOX (UROCYON LITTORALIS)

Abstract Our previous investigations of some of the lesser-known canids suggested that deviations from the patterns exhibited by the more extensively studied species such as wolves and coyotes might be found in other canids. We used fecal estrogen and progestin profiles from captive colonies to describe the basic reproductive pattern of island foxes (Urocyon littoralis). Based on sustained increases in levels of fecal progestin as indicative of ovulation, we determined that 11 of 13 females housed with males ovulated. In contrast, we detected no ovulations in 10 females housed alone and only 1 possible ovulation among 10 additional females housed in female–female pairs. Of the 2 females with males that failed to ovulate, 1 did ovulate the subsequent year while with the same male, and the other failed to ovulate when paired with a yearling male, perhaps due to his immaturity and inexperience. Significantly higher fecal estrogen levels in ovulating compared to non-ovulating females suggest that estrus was induced by the presence of a male. However, these results cannot distinguish whether male-induced estrus was followed by an induced or spontaneous ovulation, because estrogen levels indicative of estrus were always followed by ovulation. Fecal cortisol levels did not differ by ovulatory status, indicating that ovulation was not inhibited by stress mediated by glucocorticoids. Our results are the 1st to provide evidence of induced estrus, perhaps followed by induced ovulation, in a canid species, features that could have selective advantage for this less social, more secretive canid.

Effect of anosmia on reproduction in male and female wolves (Canis lupus)

Anosmia was produced in two female and three male wolves by transection of the olfactory peduncle and was confirmed by their inability to detect meat, urine, feces, anal-gland secretions, and fish emulsion. All operated animals continued to investigate the environment with their noses, to interact normally with other pack members, and to feed at levels which maintained presurgical body weights. No effect was found on reproductive physiology (females: estradiol or progesterone concentrations, ovulation, pregnancy or parturition; males: testosterone, testicular recrudescence or sperm numbers, motility or maturation). One anosmic female became dominant and although she urine-marked with a flexed leg, the rate was lower than typical for dominant females and perhaps contributed to her failure to pair-bond with the dominant male. One anosmic male raised-leg-urinated while competing for pack dominance and when kenneled away from other males. Precopulatory, copulatory, and maternal behavior were observed for one anosmic female and appeared normal. However, neither male that was sexually naive before surgery showed interest in proestrous or estrous females. The possibility that secondary degeneration of brain regions mediating sexual behavior was responsible for the failure of these males to respond was not supported. Not only was the lack of male sexual response the only serious deficit following transection, but the male which was sexually experienced prior to surgery did copulate successfully during his second postoperative breeding season despite continued anosmia. Chemosensory priming from female urine during the protracted proestrous phase, as well as urinary and vaginal odors during estrus, appear to be critical for induction of full sexual potency in sexually naive males. The importance of urine and vaginal secretions in the sexual response of experienced males is uncertain.

Vitrification of oocytes from endangered Mexican gray wolves (Canis lupus baileyi)

Careful genetic management, including cryopreservation of genetic material, is central to conservation of the endangered Mexican gray wolf. We tested a technique, previously used to vitrify human and domestic animal oocytes, on oocytes from domestic dogs as a model and from the endangered Mexican wolf. This method provided a way to conserve oocytes from genetically valuable older female Mexican wolves as an alternative to embryos for preserving female genes. Oocytes were aspirated from ovaries of 36 female dogs in December and March (0 to 65 oocytes per female) and from six female wolves (4 to 73 per female) during their physiologic breeding season, or following stimulation with the GnRH agonist deslorelin. Oocytes from dogs were pooled; half were immediately tested for viability and the remainder vitrified, then warmed and tested for viability. All oocytes were vitrified by being moved through media of increasing cryoprotectant concentration, placed on Cryotops, and plunged into liquid nitrogen. There was no difference in viability (propidium iodide staining) between fresh and vitrified, warmed dog oocytes (65.7 and 61.0%, respectively, P = 0.27). Oocyte viability after warming was similarly assessed in a subset of wolves (4 to 15 oocytes from each of three females; total 29 oocytes). Of these, 57.1% of the post-thaw intact oocytes were viable, which was 41.4% of all oocytes warmed. These were the first oocytes from a canid or an endangered species demonstrated to have maintained viability after vitrification and warming. Furthermore, our results demonstrated that vitrification of oocytes with the Cryotop technique was an option for preserving female gametes from Mexican wolves for future use in captive breeding programs, although in vitro embryo production techniques must first be developed in canids for this technique to be used.

THE EFFECT OF THE MALE BUSH DOG (SPEOTHOS VENATICUS) ON THE FEMALE REPRODUCTIVE CYCLE

Abstract In a 2-year study of the bush dog (Speothos venaticus), a small canid from Central and South America, we examined the reproductive physiology of mature females and the effect of male presence on the incidence and timing of ovulation. Fecal hormones, vulvar measurements, and mating behavior were used to characterize reproductive cycle dynamics. As described for all other canids, female bush dogs have an obligate pseudopregnancy after an infertile mating or ovulation without mating. However, the female cycle is not fixed to a single rigid breeding season each year, as in most canids. Unlike other canids, the presence of a male was associated with shortened interestrous intervals and increased number of estrous cycles. Examination of preliminary testosterone data from males showed a nonseasonal pattern suggesting that males have year-round, not seasonal, sperm production. The results from this study, including the validation of the noninvasive fecal hormone monitoring technique used, can provide managers of captive animals with tools for optimizing breeding potential of this species.

Production of Hybrids Between Western Gray Wolves and Western Coyotes

Using artificial insemination we attempted to produce hybrids between captive, male, western, gray wolves (Canis lupus) and female, western coyotes (Canis latrans) to determine whether their gametes would be compatible and the coyotes could produce and nurture offspring. The results contribute new information to an ongoing controversy over whether the eastern wolf (Canis lycaon) is a valid unique species that could be subject to the U. S. Endangered Species Act. Attempts with transcervically deposited wolf semen into nine coyotes over two breeding seasons yielded three coyote pregnancies. One coyote ate her pups, another produced a resorbed fetus and a dead fetus by C-section, and the third produced seven hybrids, six of which survived. These results show that, although it might be unlikely for male western wolves to successfully produce offspring with female western coyotes under natural conditions, western-gray-wolf sperm are compatible with western-coyote ova and that at least one coyote could produce and nurture hybrid offspring. This finding in turn demonstrates that gamete incompatibility would not have prevented western, gray wolves from inseminating western coyotes and thus producing hybrids with coyote mtDNA, a claim that counters the view that the eastern wolf is a separate species. However, some of the difficulties experienced by the other inseminated coyotes tend to temper that finding and suggest that more experimentation is needed, including determining the behavioral and physical compatibility of western gray wolves copulating with western coyotes. Thus although our study adds new information to the controversy, it does not settle it. Further study is needed to determine whether the putative Canis lycaon is indeed a unique species.