Austrian researchers have tested the reliability of scanners in reading microchips implanted in horses, saying they can recommend only top-of-the-range scanners.
Traditional methods of marking larger farm animals have relied on branding with hot irons or on ear-tagging.
Until recently, horses were generally branded to be able to identify individual animals. Since this practice gives rise to longstanding wounds and brand marks cannot always be reliably read, there has been a gradual switch toward microchips.
With very few exceptions, it is now mandatory within the European Union to mark horses by means of transponders. Nevertheless, some sport-horse registries oppose the use of microchips because they believe that the rate of identification failure is unacceptably high.
To date, no systematic examinations to see whether chips are easy to decode have been conducted.
Manuela Wulf, in the team of Professor Christine Aurich at Vetmeduni Vienna – the University of Veterinary Medicine in the Austrian capital – examined the readability of microchips in more than 400 horses.
Wulf tested each of the chips with three different scanners. The scanners differed in diameter and field strength. The scientists tested both sides of the animals’ necks.
The results were intriguing.
The “best” scanner – equipped with a digital signal processing function that filters interfering signals – detected and read all chips correctly when it was placed on the side of the neck where the chip was implanted and located nearly 90 percent of the chips even when it was on the other side of the neck.
However, the other two scanners performed considerably less well, producing correct reads in around 90 per cent of the cases when on the same side of the neck.
On the opposite side of the neck, the success rate ranged between 20-25 percent.
“It is important that the scanners find and read the chips correctly in every case,” Wulf said.
“We can only recommend the top-of-the-range scanner, which should ideally be placed on the side of the horse’s neck where the chip was implanted.”
However, Aurich adds: “Even the lowest quality scanner we tested, performed much better than traditional branding methods of horse identification.”
The readability of traditional brands has been the subject of earlier research at the university.
The major objection to the use of branding relates to the pain and long-term damage it inflicts on the animals.
Wulf and her colleagues went on to investigate whether the use of microchip markers was any better.
She looked closely at the site of chip implantation in 16 horses of nine different breeds and of various ages that had been submitted to the university for post mortem examinations.
In the vast majority of cases, the chips seemed to have caused absolutely no ill effects: the two animals that were moderately affected had probably been chipped only recently and there had not yet been time for the wound to heal.
Aurich comments: “Not only is chipping a far more reliable method for marking horses than traditional methods of branding, we also found that it causes far less injury to the animals.”
The field work for the microchip research was carried at the Graf Lehndorff Institute for Equine Science, a joint research unit of the University of Veterinary Medicine in Vienna and the Brandenburg State Stud at Neustadt (Dosse), Germany.
The post mortems were performed at the Department of Pathology, University of Veterinary Medicine, in Hannover, Germany.
The paper Readability of microchip transponders and histopathological findings at the microchip implantation site in horses, by Manuela Wulf, Peter Wohlsein, Jörg E. Aurich, Marina Nees, Wolfgang Baumgärtner and Christine Aurich, has just been published online in The Veterinary Journal (http://dx.doi.org/10.1016/j.tvjl.2013.04.028).