Abstract
Veterinary care and intervention have played and continue to play a prominent role in the recovery and reintroduction of the black-footed ferret. From the last 18 ferrets (7 founder animals) salvaged from plague and distemper outbreaks in Wyoming, we now have over 500 captive individuals. Approximately 240 of these are breeding adults. The United States Fish and Wildlife Service oversees the re-introduction of ferrets and coordinates with the six AZA breeding facilities to allocate appropriate animals for release. Over 500 individuals have been re-introduced to parts of their former range. With the current average success rate of approximately 30%, there are at least 50 free-ranging ferrets in Montana, South Dakota, Arizona and Wyoming. The primary threat to initial survival is predation from coyotes and raptors. All released ferrets have passive transponders and most are fitted with radio-collars. Post-release monitoring includes radio telemetry and spotlighting from all-terrain vehicles. Once a ferret is located, the passive transponders can be read remotely from burrows to identify individuals. Juvenile kits of the year are trapped, serologically evaluated for exposure to plague and distemper and implanted with a transponder.
Veterinarians such as Tom Thorne, Beth Williams and JoGayle Howard have played integral roles in the success of the black-footed ferret program. Veterinary involvement is still just as critical today. In addition to loss of its habitat and primary prey base from prairie dog eradication, disease continues to have a significant effect on the ferret’s endangered status. Although there have been no documented deaths in released ferrets attributable to disease, sylvatic plague and canine distemper are two of the most serious diseases that the ferrets will likely face upon reintroduction. Preliminary studies are pending with regard to ways to prevent plague in reintroduced black-footed ferrets and their offspring. Possibilities include the use of an insect growth regulator, pyriproxyfen for use in prairie dogs and/or developing an oral plague vaccine for use in ferrets.
Canine distemper has long been known to be a fatal disease of black-footed ferrets. Work is currently underway by Dr. Beth Williams, Dr. Dick Montali, Dr. Werner Heuschle and others to re-develop a killed virus or a recombinant canine distemper vaccine for use with all black-footed ferrets. At present, Dr. Max Appel has come out of retirement to once again provide his killed virus vaccine until a safe and effective replacement can be manufactured and distributed in the United States.
Dr. JoGayle Howard continues to use her successful artificial insemination technique on black-footed ferrets to help maximize their existing genetic diversity by circumventing behavioral problems with genetically optimal pairings and by inseminating females that come into estrus after the male has gone out of breeding condition. She is also creating a genome resource bank for the black-footed ferret.
As more ferrets are released and reproduce in the wild, there is an increased need to capture, anesthetize, transponder, collar and serologically evaluate the free-ranging animals. New techniques are developing for practical and safe methods of field anesthesia. Dr. Terry Kreeger is investigating the use of ketamine/medetomidine and atipamezole. The Montana and South Dakota release sites also have been using portable isoflurane anesthetic machines to achieve the brief immobilization needed for processing free-ranging black-footed ferrets.