Long-Term Safety of Intraperitoneal Radio Transmitter Implants in Brown Bears (Ursus arctos)

Abstract

Intraperitoneal radio transmitters have been widely used in free-ranging wild mammals, but there are no long-term studies on their biocompatibility or technical stability within the abdominal cavity of animals. Possible negative health effects may bias results from ecological studies on instrumented animals and raise concerns over animal welfare issues. The aim of this study was to evaluate the long-term technical stability and pathological effects of Telonics intraperitoneal very high frequency (VHF) radio transmitters in brown bears (Ursus arctos). We instrumented 305 individual bears with intraperitoneal VHF radio transmitters during a 19-year period. We surgically removed devices that had been in bears for 1–9 years and collected transmitters from animals that died 1–13 years after implantation. We took biopsies for histopathology from tissue encapsulating implants in live bears. Retrieved transmitters underwent a technical inspection. Of the 125 transmitters removed from live bears, 66 were free-floating in the peritoneal cavity [a mean (SD) of 3.8 (1.5) years after implantation], whereas 59 were encapsulated in the greater omentum [4.0 (1.8) years after implantation]. Histopathology of biopsies of the 1–15 mm thick capsules in 33 individuals showed that it consisted of organized layers of connective tissue. In one third of the bears, the inner part of the capsule was characterized by a foreign body reaction. We inspected 68 implants that had been in bears for 3.9 (2.4) years. The batteries had short-circuited four (5.9%) of these devices. This resulted in the death of two animals 10 and 13 years after implantation. In two other bears that underwent surgery, we found the short-circuited devices to be fully encapsulated within the peritoneal cavity 5 and 6 years after implantation. A significant proportion of the other 64 inspected implants showed serious technical problems, such as corrosion of metal parts or the batteries (50%), detachment of the end cap (11.8%), and erosion (7.4%) or melting (5.9%) of the wax coating. We conclude that the wax coating of the transmitters was not biocompatible, that the technical quality of the devices was poor, and that these implants should not be used in brown bears.

Towards more compassionate wildlife research through the 3Rs principles: moving from invasive to non-invasive methods

“…Particularly problematic is the use of implanted transmitters as this involves additional trauma to the animal. The recent study by Arnemo et al (2018) showed that transmitters implanted into the abdominal cavities of brown bears Ursus arctos performed poorly and were not biocompatible, in several cases causing the animal's death. Several cases of mortality caused by implanted radio-transmitters have been reported also in European lynx Lynx lynx (Lechenne et al 2012), Harlequin ducks Histrionicus histrionicus (Mulcahy and Esler 1999) and American badgers Taxidea taxus (Quinn et al 2010).…”

Retention and Loss of PIT Tags and Implanted VHFs and Bio-Loggers in the Eurasian Beaver

“…Transmitter loss was also reported for birds and reptiles (47,48). In contrast, in a study implanting 305 brown bears with VHF transmitters reported no loss (11). These contrasting ndings indicate that species differences (physiology, immune system etc.)…”

“…Most studies have reported successful results without complications, whereas others document varying tissue responses. A study on brown bears (Ursus arctos) reported corrosion of parts of implanted devices and leakage from short-circuited batteries, which resulted in the death of two study animals (11). The same study found a varying degree of tissue foreign body reaction to the implanted devices, ranging from no reaction to light encapsulation to thick capsule formation.…”

“…peritoneal loggers (3,(10)(11)(12). Most studies have reported successful results without complications, whereas others document varying tissue responses.…”

The Dividing Line Between Wildlife Research and Management—Implications for Animal Welfare

“…The lack of expertise can unfortunately result in failing to ask the important questions to the investigators. Examples of such questions include asking how a transmitter is aerodynamically designed, rather than just asking how much the transmitter weighs in relation to the weight of the animal, or how the transmitter can affect movement and health of the animals ( 15 , 29 ), or the short- and long-term risks on health and welfare from capture and handling ( 4 ). The research procedures in traditional laboratory settings affect animals confined in a controlled environment.…”