Neoplasia and Granulomas Surrounding Microchip Transponders in Damaraland Mole Rats (Cryptomys damarensis)

Abstract

Damaraland mole rats (Cryptomys damarensis) are among the longest-living rodents, with a maximum longevity of approximately 16 years. As one of the few mammals termed eusocial, these animals have been used in behavioral, genetic, metabolic, and physiologic research at the University of Connecticut since 1997. For individual identification at 3 to 4 months of age, mole rats were subcutaneously implanted with microchip transponders (11 mm in length) in the dorsal cervical region. In 2007, 2 of the 90 implanted adults, 10-year-old and 9-year-old females, developed subcutaneous masses at the site of the implant. Histopathological and immunohistochemical examinations revealed amelanotic melanoma and fibrosarcoma, respectively, with metastasis of the amelanotic melanoma. In 2008, a total of 3 adult males were castrated as part of a sex behavior study; 3 months later, all 3 castrated males developed subcutaneous masses around their implants, whereas none of the noncastrated males had masses. After an additional 9 months, these masses were found to be granulomas. To the authors' knowledge, this is the first report of neoplasia in this species. Both the tumors and the granulomas surrounded the microchip transponder.

Peritoneal Sarcomatosis Associated with Telemetry Implants in Sprague Dawley CD Rats

“…Similar tumors have been observed, albeit infrequently, at microchip implantation sites, and these tumors also are associated with chronic inflammation (Sura et al 2011; Tillmann et al 1997; Troyk 1999). Although the use of telemetry devices in rats and other species is not new, the development of malignant neoplasms in the peritoneal cavity following abdominal implantation of telemetry devices in rats has not been reported.…”

“…Several studies and some case reports that indicate that microchip–transponder implants have been associated with neoplasia in different animals including laboratory mice and rats, and pet dogs (Ball et al 1991; Blanchard et al 1999; Elcock et al 2001; Jansen et al 1999; Lambooij 1995; Mader et al 2002; Pessier et al 1999; Siegal-Willott et al 2007; Sura et al 2011; Tillmann et al 1997; Troyk 1999; Vascellari et al 2004; Vascellari et al 2006). The majority of transponder-associated tumors have been mesenchymal in origin, and the mechanism of carcinogenicity is thought to be foreign body–induced tumorigenesis (Brand et al 1976; Elcock et al 2001).…”

Social Status and Sex Effects on Neural Morphology in Damaraland Mole-Rats, <i>Fukomys damarensis</i>

“…They are among the longest-lived rodents, surviving over 15 years in captivity [Sura et al, 2010], and breeders remain reproductively active throughout their long lifespan. Table 1 provides the mean ages and body weights of all animals used in this study (n = 26).…”