Long-Term Evaluation of Telonics® Intraperitoneal Radiotransmitters in Free-Ranging Brown Bears (Ursus arctos)
Intraperitoneal radiotransmitters (Telonics, Inc., Mesa, AZ, USA) were surgically implanted into 155 free-ranging, brown bears (Ursus arctos) from 1997 through 2006. The bears were anesthetized with medetomidine-tiletamine-zolazepam, and surgeries were carried out using a standardized protocol.1 Based on recommendations from the manufacturer, implants were disinfected by soaking in benzalkonium chloride prior to implantation.2-4
Implants were removed surgically from 28 bears after 3–9 years. In 14 bears [mean 5.5 (range 3–9) years after implantation], the implants were found free-floating. In 14 bears [5.7 (3–8) years], the implants were encapsulated in the omentum and surrounded by 1–4 mm of connective tissue. In seven of these animals [6.0 (5–8) years], the implants were encapsulated in and required amputation from an umbilicated and twisted loop of the omentum. Bacterial culture from the capsules and surface of the implants yielded no growth. Technical inspection (n=26) showed signs of wear or discoloring of the wax on nine implants. Relative humidity inside the waterproof plexiglass cylinder was 5–20% and corrosion of the battery was seen in 18 implants.
Most biopsies from the capsules showed a moderate inflammatory reaction. However, a granulomatous inflammation in some capsules indicated a delayed-type hypersensitivity reaction. Aggregates of foamy macrophages filled with yellowish material may indicate that these cells phagocytose the wax covering the transmitters. Multiple hemorrhages in the capsules may have been caused by minor trauma from pendulous movements of the transmitter.
Contrary to advice from the manufacturer,4 we recommend that Telonics® intraperitoneal implants should be removed surgically prior to expiry of the batteries.
1. Arnemo, J.M., and Å. Fahlman (eds.). 2007. Biomedical protocols for free-ranging brown bears, gray wolves, wolverines, and lynx. Norwegian School of Veterinary Science, Tromsø, Norway.
2. Technical note # 830727-1 Implantable biotelemetry. 1983. Telonics, Inc., Mesa, Arizona, USA.
3. Burger, B., D. DeYoung, and D. Hunter. 1994. Sterilization of implantable transmitters. Telonics Quarterly™ 7(3):3–4.
4. Telonics Inc., Mesa, Arizona, USA. www.telonics.com/products/vhfImplants (7 April 2007).