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ABSTRACT: Wildlife, free-ranging and captive, poses and causes serious population problems not unlike those encountered with human overpopulation. Traditional lethal control programs, however, are not always legal, wise, safe, or publicly acceptable; thus, alternative approaches are necessary. Immunocontraception of free-ranging wildlife has reached the management level, with success across a large variety of species. Thus far, the immunocontraceptive research and management applications emphasis have been centered on porcine zona pellucida and gonadotropin-releasing hormone vaccines. Contraceptive success has been achieved in more than 85 different wildlife species, at the level of both the individual animal and the population. At the population management level with free-ranging species, the primary focus has been on wild horses, urban deer, bison, and African elephants. The challenges in the development and application of vaccine-based wildlife contraceptives are diverse and include differences in efficacy across species, safety of vaccines during pregnancy, the development of novel delivery systems for wild and wary free-ranging animals, and the constraints of certain non-contraceptive effects, such as effects on behavior. Beyond the constraints imposed by the public and a host of regulatory concerns, there exists a real limitation for funding of well-designed programs that apply this type of fertility control.
American Journal Of Reproductive Immunology 07/2011; 66(1):40-50. · 2.17 Impact Factor
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ABSTRACT: Urine-soaked snow from 13 uncaptured feral mares was collected and measured without extraction for estrone conjugates (E1C) and nonspecific immunoreactive pregnanediol-3-glucuronide (iPdG) by enzyme immunoassays. The hormone values were indexed to creatinine (Cr). Mares that produced foals had urinary E1C values of 7.30 ± 1.39 (SE) μg/mg Cr versus 0.096 ± 0.084 μg/mg Cr for mares that did not produce foals. The difference was significant (P < 0.001). Nonspecific iPdG concentrations for mares producing foals was 167 ± 80.33 ng/mg Cr versus 7.04 ± 1.69 ng/mg Cr for mares that did not produce foals. The difference was significant (P < 0.0025). Urine samples collected directly from the ground from 34 uncaptured feral mares were measured for E1C and nonspecific progesterone metabolites and compared with fecal total estrogen concentrations in matched fecal samples, measured by means of radioimmunoassay. Both E1C and iPdG concentrations differed significantly (P < 0.001) between mares producing foals and those that did not. Mean fecal total estrogen concentrations for mares producing foals was 3.18 ± 0.70 ng/g feces versus 0.552 ± 0.08 ng/g feces for those that did not produce foals. The difference was significant (P < 0.001). The correlation coefficient between urinary E1C and fecal total estrogens was 0.928. The results indicate that both urine-soaked snow and fecal samples can be used to reliably assess pregnancy in uncaptured free-roaming feral horses.
Canadian Journal of Zoology 02/2011; 68(12):2576-2579. · 1.21 Impact Factor
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ABSTRACT: A population of feral horses (Equus caballus) was studied from 1986 to 1991 to determine the demographic impact of predation by the mountain lion (Felis concolor). The population, inhabiting a 600-km2 area on the central California – Nevada border comprised approximately 162 individuals > 1 year old, with an average of 9 yearlings, 8 two-year-olds, and 144 adults. Numbers of horses varied by only 4–8% and showed no consistent trend. The parturition peak spanned May and June, when 80% of foaling occurred. One-third of the average annual cohort of 33 foals was missing by July and only half of the cohort remained by October. The mean first-year survival rate estimated from the differential incidence of foals and yearlings in successive years was 0.27, which was less than one-third of the foal survival rate reported for other feral horse populations. A minimum of four adult mountain lions used the study area each year between May and October. Of 28 foal carcasses located from May to mid-July, at least 82% were the result of mountain lion kills. No evidence of predation on older horses was observed, but mountain lions preyed on mule deer (Odocoileus hemionus) during winter. We conclude that the growth of this horse population is limited by predation.
Canadian Journal of Zoology 02/2011; 70(5):929-934. · 1.21 Impact Factor
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ABSTRACT: It was the goal of this study to develop a reliable behavioral endpoint for use in studying patterns of reproduction and methods for regulating reproduction in feral horses. Several characteristic stallion behavior patterns associated with harem activities were examined. The only behavior which occurred with high frequency and was readily observable and quantifiable was stallion elimination marking behavior in which stallions marked eliminations (urinations–defecations) of other horses with their own urine and feces. Elimination marking behavior was not exhibited by mares or immature animals and stallions rarely marked eliminations made by immatures. Stallion response to eliminations by mature mares varied markedly with time of year, averaging 93% and 89% in May and June, the peak of the breeding season, and 1% from November through February. Thus, seasonal changes in elimination marking behavior were well correlated with the breeding season. The completeness of the behavior pattern showed an annual pattern similar to that for frequency. The possible significance of this behavior in relation to feral horse social organization and its use as a behavioral correlate in studying reproductive patterns is discussed.
Canadian Journal of Zoology 02/2011; 59(8):1561-1566. · 1.21 Impact Factor
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ABSTRACT: ABSTRACT ABSTRACT Previous studies reported one year of contraception associated with a 1-injection porcine zona pellucida (PZP) vaccine. We have subsequently determined contraceptive effectiveness of a presumptive 1-injection, 2-year-duration PZP vaccine in free-roaming wild horses (Equus caballus) in Nevada, USA. In January 2000, we captured, freeze-branded, treated, and subsequently released 96 adult females that received 1) a primary dose of vaccine emulsion consisting of aqueous PZP and Freund's Complete Adjuvant, and 2) booster doses of PZP and adjuvant in controlled-release polymer pellets. We determined PZP release characteristics of pellets in vitro, prior to field use. We determined reproductive success in treated and untreated females through October 2004 via measurement of estrone sulfate and progesterone metabolites in fresh feces collected from the ground and by twice-annual foal counts. Among treated females, annual reproductive success from 2001 though 2004 sequentially was 5.9%, 14.0%, 32.0%, and 47.5%. Untreated females showed average reproductive success of 53.8 ± 1.3% across this period. This study revealed that: 1) PZP acted as an effective contraceptive for 2 years posttreatment; 2) some residual contraceptive effect remained in year 3; and 3) fertility returned to control levels by year 4 posttreatment. It appears that controlled-release technology can replace both the second(1-month) and annual booster injection of PZP vaccine, thereby decreasing cost and increasing efficiency of use of this vaccine in wild horse management.
Journal of Wildlife Management 12/2010; 71(2):662 - 667. · 1.52 Impact Factor
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ABSTRACT: Intensive population management by means of fertility control has been shown to change the age profile of a wild horse herd. The primary change has been an increase in the number and percent of older animals, as expected, but also the appearance of new and older age classes. An examination of direct effects of fertility control on two groups of treated animals shows a significant increase in longevity over non-treated animals that is associated with contraceptive treatment. The mean age at death (MAD) was calculated for 128 wild horses for which precise birth and death dates were known, including 56 stallions, 42 untreated mares, 11 mares treated with a porcine zona pellucida contraceptive vaccine for 1-2 years, and 19 mares treated with the same vaccine for >/=3 years. The MAD for stallions (10.3+/-0.84 [SEM] years), and mares treated for 1-2 years (10.2+/-0.56), was significantly greater (P<0.05) than for untreated mares (6.4+/-0.85), and significantly <19.9+/-1.66 for mares treated >/=3 years (19.9+/-1.66). Zoo Biol 26:237-244, 2007. (c) 2006 Wiley-Liss, Inc.
Zoo Biology 08/2007; 26(4):237-44. · 0.84 Impact Factor
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Jay F Kirkpatrick
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ABSTRACT: There are few wildlife populations existing today that can be supported without some form of management. Wildlife fertility control, as one option, has moved from the research stage to actual application with a number of species, including wild horses, urban deer, captive exotic species and even African elephants, but this approach remains controversial in many quarters. Strident debate has arisen over the possible effects of contraception on behaviour, genetics, stress and even management economics, among other parameters. Part of the debate arises from the fact that critics often fail to recognise that some form of alternative management will be applied, and a second problem arises when critics fail to identify and demand the same concern for the consequences of the alternative management approaches. Thus, any rational debate on the merits or possible effects of contraceptive management of wildlife must also recognise all alternative management approaches and apply the same concern and questions to these alternative approaches--including 'no management'--as are currently being applied to fertility control. Only then will the stewards of wildlife be in a position to make wise and informed decisions about management options.
Reproduction Fertility and Development 02/2007; 19(4):548-52. · 2.11 Impact Factor
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ABSTRACT: Fifteen captive wild mares (Equus caballus) were treated with porcine zona pellucida contraceptive vaccine and either Freund's Complete Adjuvant (n = 7) or Freund's Modified Adjuvant (n = 8). All mares received a booster inoculation of porcine zona pellucida plus Freund's Incomplete Adjuvant a month later. Anti-porcine zona pellucida antibodies were measured over 10 mo following the initial inoculation. There were no significant differences in antibody titers at any point during the 10 mo, and seven of the eight mares in the Freund's Modified Adjuvant group were above the 60% level at the end of the study, which is considered to be the contraceptive threshold for horses. There were no significant differences in titers between pregnant and nonpregnant horses, nor was there a significant correlation between age and titers. One local injection site reaction occurred after booster treatment with Freund's Incomplete Adjuvant, and 11 healthy foals were born during the course of the study. These data suggest that Freund's Modified Adjuvant is an acceptable substitute for Freund's Complete Adjuvant in certain free-ranging and captive wildlife species.
Journal of Zoo and Wildlife Medicine 01/2006; 36(4):610-6. · 0.38 Impact Factor
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ABSTRACT: The biological efficacy of porcine zona pellucida (PZP) immunocontraception and the timing of booster inoculations were determined in 24 species of ungulates and five species of non-ungulates across 10 years of treatment and for which no technical problems were identified. The collective contraceptive efficacy for 265 ungulates, 25 bears, and 11 sea lions, across 517 contraceptive intervals was 93.3%, and contraceptive efficacy ranged from a low of 60% in nyala (Taurotragus angasi) to 100% in 16 other species. The timing of annual booster inoculations was adjusted, between 6 months and 12 months, depending on the length of the breeding season and the species-specific immune responses. The high degree of efficacy in bears and sea lions suggests that the PZP vaccine has some application in certain non-ungulate species. Technical problems in the timing and delivery of the vaccine can cause non-biological failures and were identified in an additional 20 animals, not included above, and included inoculating pregnant animals, the use of needles too short for effective intramuscular injections, failure to complete the initial inoculation series, and failure to give booster inoculations at the prescribed time. Zoo Biol 0:1–10, 2005. © 2005 Wiley-Liss, Inc.
Zoo Biology 05/2005; 24(4):349 - 358. · 0.84 Impact Factor
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ABSTRACT: Methods of contraception are necessary for management of zoo felids; however, the most commonly used contraceptive (melengestrol acetate implant) is associated with serious adverse reactions with long-term use. Porcine zona pellucida (pZP) vaccines are promising as contraceptives, but their safety in zoo felids has not been tested. pZP vaccine was administered to 27 female felids representing 10 species, including African lion (Panthera leo), Asian leopard (P. pardus), jaguar (P. onca), tiger (P. tigris), snow leopard (P. uncia), cougar (Felis concolor), Siberian lynx (F. lynx), Canada lynx (F. canadensis), serval (F. serval), and bobcat (F. rufus), in 15 facilities. Over 6 wk, each animal received three i.m. injections of 65 microg pZP with Freund's complete adjuvant (FCA), Freund's incomplete adjuvant, or carbopol as the adjuvant. Behavioral signs of estrus were seen in 14 of the vaccinated felids. An unacceptably high incidence of adverse reactions was seen including injection site swelling, lameness, limb swelling, or abscessation (or all) in five felids after injection with FCA as the initial adjuvant. Adverse behavioral signs, including increased irritability and aggression, were seen in four felids. Six of the felids were assayed for antibodies against pZP during the 12 mo after vaccination; all showed antibody production. Antibody levels appeared to peak 1-4 mo after vaccination began, although elevated antibody levels persisted in two animals for > 12 mo after the first injection. All vaccinated felids were ovariohysterectomized 3-13 mo after vaccination. Folliculogenesis was present in all treated animals, and there was no histopathologic evidence of inflammatory damage to ovaries. Contraceptive efficacy was not specifically evaluated in this study; however, two of the three felids housed with an intact male became pregnant during the study, one of which gave birth to healthy cubs.
Journal of Zoo and Wildlife Medicine 09/2004; 35(3):271-9. · 0.38 Impact Factor
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ABSTRACT: Immunocontraception has become an increasingly valuable tool in the population management of captive exotic ungulates. Although porcine zona pellucida vaccine (PZP) was used successfully in other cervids, a previous study with fallow deer (Cervus dama) suggested that the vaccine did not work in this species. In the current study, PZP was tested in two captive herds of fallow deer. Antibody titers were monitored over a 3-year period to evaluate three different adjuvant protocols, and the vaccine was applied to an entire herd to determine the impact on fawning rates. In a semi-free-ranging herd, antibody titers rose from preimmunization levels of 2.6% of positive control serum to 56.5% 4 weeks after initial inoculations, to 65.1% at 1 year, and to 81.3% at 2 years, after a single annual booster was applied. Fawn production in this herd was reduced significantly over 3 years. The adjuvant protocol of Freund's Modified Adjuvant® (FMA) for the initial inoculation followed by a booster with Freund's Incomplete Adjuvant® (FIA), and the protocol of FMA for the initial inoculation followed in 3 weeks by a booster with FMA both produced significantly higher antibody titers than the 3× FIA (3 weeks apart) protocol after year 1. The FMA+FMA protocol produced significantly higher titers than the 3× FIA protocol at year 2, but was not different from the titers produced by the FMA+FIA protocol at year 2. Zoo Biol 22:261–268, 2003. © 2003 Wiley-Liss, Inc.
Zoo Biology 06/2003; 22(3):261 - 268. · 0.84 Impact Factor
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ABSTRACT: Despite a large body of safety data, concern exists that porcine zonae pellucidae (PZP) immunocontraception--used to manage wild horse populations--may cause out-of-season births with resulting foal mortality. Our study at Assateague, Maryland indicated the effects of immunocontraception on season of birth and foal survival between 1990 and 2002 on wild horses from Assateague Island. Among 91 mares never treated, 69 (75.8%) of foals were born in April, May, and June (in season). Among 77 treated mares, 50 (64.9%) were born in season. Of 29 mares foaling within 1 year after treatment (contraceptive failures), 20 (68.9%) were born in season. Of 48 mares treated for greater than 2 years then withdrawn from treatment, 30 (62.5%) of 48 foals were born in season. There were no significant differences (p <.05) between either treatment group or untreated mares. Survival did not differ significantly among foals born in or out of season or among foals born to treated or untreated mares. Data indicate a lack of effect of PZP contraception on season of birth or foal survival on barrier island habitats.
Journal of Applied Animal Welfare Science 01/2003; 6(4):301-8. · 0.73 Impact Factor
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Jay F. Kirkpatrick
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ABSTRACT: A unique application of immunocontraception is the wildlife populations. While there are limitations to this technology, the PZP vaccine can successfully manage certain wildlife populations, humanely, and without lethal controls
