DiazaCon reduces black-tailed prairie dog reproduction in Colorado

Abstract

Context. Black-tailed prairie dogs (Cynomus ludovicianus) often come into conflict with humans in urban natural areas adjacent to private property by destroying plants and denuding the landscape. There is a diversity of attitudes related to urban prairie dog management in Colorado and interest in non-lethal methods is increasing. Therefore, the development of non-lethal methods that allow the existence of prairie dogs and mitigate damage related to population density is needed.Aims. The efficacy of DiazaCon (20,25-diazacholesterol dihydrochloride, a cholesterol analogue) as an oral contraceptive bait for reducing reproduction in black-tailed prairie dogs was tested. Persistence of DiazaCon in black-tailed prairie dogs 11 months after initial application was also determined.Methods. Prairie dogs were baited with DiazaCon-coated rolled oats or control bait for 10 days over a 20-day period in November 2007 on one control and one treatment site. Sites were randomly assigned to a treatment group. Visual counts were used 8 months post-treatment (June/July 2008) to determine pup : adult ratios on both sites. Prairie dogs on both sites were trapped 11 months post-treatment (September/October 2008) to gather mass and age data to assess juvenile : adult ratios and to collect blood samples for determination of serum cholesterol and desmosterol concentrations.Key results. DiazaCon treatment reduced the number of pups per adult by 95.5% when compared with the control site in June/July 2008 (0.09 AE 0.02, n = 10, number of observation days) versus 2.0 AE 0.2 (n = 10). Free serum cholesterol levels in treated animals (370.7 mg mL -1 ) were lower than control animal levels (411.6 mg mL -1, P < 0.015), while treated desmosterol levels (14.5 mg mL -1 ) were higher than controls (0.35 mg mL -1 , P < 0.02) 11 months after ingestion of DiazaCon bait. However, these differences would likely not have been sufficient to prevent successful breeding in the upcoming breeding season.Conclusions. DiazaCon is an effective contraceptive in black-tailed prairie dogs. It is probably reversible and will likely affect breeding success for only one breeding season. DiazaCon may provide an additional tool to help manage urban populations of prairie dogs in locations where lethal control is unacceptable.Implications. The need for further research into secondary hazards to non-target animals, such as predators, is discussed. Recommendations for field application are also discussed.

Reference Intervals for Plasma Biochemical Variables by Point-of-Care Testing in Captive Black-tailed Prairie Dogs (Cynomys ludovicianus)

“…Total bilirubin was previously reported to be lower in older prairie dogs, but this trend was not observed in animals tested in our current study. 50,51 However, our older prairie dogs tended to show a decrease in albumin concentration and increases in the total protein and globulin concentrations compared with juvenile animals, and similar trends have been reported for guinea pigs, rats, and degus (Octodon degus). 27,29,46 Older mice and rats tend to show lower blood glucose concentrations.…”

“…Compared with adults in this study, juvenile prairie dogs tended to show higher ALP and ALT concentrations-similar to the findings from wild-caught prairie dogs tested with the same veterinary POS analyzer. 50,51 Similar observations have been reported for guinea pigs, rats, mice, degus, and giant rats (Cricetomys gambianus). 14,27,29,37 Increased serum or plasma ALT activity is a relatively specific indicator of hepatocellular damage in relevant species, but as with all biochemical analytes, abnormal results must be interpreted in light of other laboratory data and clinical signs.…”

“…28 Another study used the same veterinary POC analyzer as in the current study to evaluate a contraception vaccine and tested its effect on plasma biochemical analytes in wild-caught juvenile prairie dogs. 50,51 Some of the differences in RI between our current study and these previous studies likely reflect preanalytical factors; however, given the absence of published data regarding the analytical performance of the veterinary POC analyzer in prairie dogs, differences between analytical methods may contribute. These findings are recapitulated in the literature, given that results for this species that were obtained by using different commercial biochemical analyzers show great variability.…”

“…14,29 In our current study, older prairie dogs had significantly lower blood glucose than juvenile animals, and this was also previously described in wild-caught prairie dogs tested using the same veterinary POC analyzer. 50,51 In addition to showing age-associated effects, blood glucose concentrations in prairie dogs vary considerably depending on the animals' origin, diet, fasting time, stress, and the testing methodology. 22,28,51 When compared with juveniles, older prairie dogs in the current study tended to show lower BUN values and higher creatinine concentrations.…”

Treatment with the immunocontraceptive vaccine, GonaCon, induces temporary fertility control in free-ranging prairie dog populations in Colorado, USA

“…The two attractive benefits of an injectable are that it (1) greatly reduces the risk to non-target exposure to the fertility control product, and (2) immediate confirmation is gained that each target animal has been exposed to the target dosage. DiazaCon, like GonaCon, has been shown to be highly effective at reducing black-tailed prairie dogs in Colorado; however, DiazaCon must be fed to prairie dogs over multiple days prior to each breeding season to realise reduced annual fecundity (Yoder et al . 2016).…”