title: Readability and histological biocompatibility of microchip transponders in horses.
abstract: Identification of horses by microchip transponder is mandatory within the European Union with only a few exceptions. In this study, the readability of such microchips in 428 horses with three different scanners (A, B and C) and the histological changes at the implantation site in 16 animals were assessed. Identification of microchips differed between scanners (P<0.001), and with 'side of neck' (P<0.001). Scanners A, B and C identified 93.5%, 89.7% and 100% of microchips, respectively, on the 'chip-bearing' side of the neck. From the contralateral side, scanners A, B and C identified 21.5%, 26.9% and 89.5% of transponders, respectively. Microchip readability was affected by age (P<0.001), but not by breed of horse. At necropsy, transponders were found in the subcutaneous fat (n=3), inter- or peri-muscular connective tissue (n=8), or musculature (n=5), where they were surrounded by a fibrous capsule ranging in thickness from 12.7 to 289.5 μm in 15 animals. In two animals, immature granulation tissue with attendant granulomatous inflammation, and a granulomatous myositis, surrounding the microchip were identified, respectively. Severe (n=1), moderate (n=1), and mild (n=3) lymphohistiocytic inflammation was noted within the fibrous capsule. Microchip transponders were found to be a highly reliable and biocompatible method of horse identification.
authors.affiliation: Graf Lehndorff Institute for Equine Science, Vienna University of Veterinary Sciences, 16845 Neustadt (Dosse), Germany.
authors.forename: M
authors.initials: M
authors.lastname: Wulf
authors.forename: P
authors.initials: P
authors.lastname: Wohlsein
authors.forename: J E
authors.initials: JE
authors.lastname: Aurich
authors.forename: M
authors.initials: M
authors.lastname: Nees
authors.forename: W
authors.initials: W
authors.lastname: Baumgärtner
authors.forename: C
authors.initials: C
authors.lastname: Aurich
mesh_terms: D000823:Animal Identification Systems / Q000295:instrumentation / Q000379:methods* / Q000662:veterinary; D000818:Animals; D004867:Equipment Design / Q000662:veterinary; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology* / Q000276:immunology; D006736:Horses / Q000601:surgery; D007249:Inflammation / Q000453:epidemiology / Q000276:immunology / Q000662:veterinary*; D008297:Male
keywords: Biocompatibility; Histopathology; Horse; Identification; Microchip