Implantation of transponders at the bottom of the ear in equines

In the present work transponders of 2 identification systems have been implanted on an exactly defined site at the bottom of the ear on 28 horses. The Backhome system is easier to handle and less complicated than the trovan system since it is smaller and handier. The hemorrhages that had occurred after the injection were mild at 17 animals and moderate at 4 animals. Inflame changes at the injection site post application were limited to minor swellings (n = 3) and minor pain (n = 6). The interrogator's scope of the two transponder systems is different. The interrogator's scope of the trovan transponder was approximate 5 to 10 cm and of the Backhome transponder approximate 15 to 25 cm resulting in a higher benefit. All 14 slaughtered horses were examined pathologically in different periods and two transponders were found to have changed their sites considerably at approximately 8 to 10 cm compared with the initial injection site. The connective tissue surrounding the transponder was transparent and thin in cases where the transponder had been implanted 30 days ago or earlier, histopathologically the tissue thickness changed. Inflammatory changes appeared in 3 cases as a minor perivasculitis and in further 5 cases as a collection of single siderophages. In the remaining 5 cases no inflammation was determined. The minor changes and lack of inflammation reflect the high biocompatibility of transponders.