As microchipping becomes more prevalent in horses—and even obligatory in some countries—researchers are looking into the effects and usefulness of these foreign objects implanted into horses’ bodies.

Microchip implantation appears to cause relatively little physical or physiological damage to horses, said Manuela Wulf, BSc, researcher at the Graf Lehndorff Institute for Equine Science in Neustadt, Germany. And for the most part, they’re a reliable source of identification, even if readability isn’t always 100%.

“Readability of the chip has a lot to do with the kind of scanner that’s used for reading, as well as how the chip was actually placed into the horse,” Wulf said.

In small animals such as cats and dogs, microchips are placed under the skin via injection. In horses, however, it’s critical that the microchip is placed into the neck muscle itself, said Wulf. “Even in small animals, microchips set under the skin can migrate,” she explained. “I know of a dog that was microchipped over the shoulder; six years later, that chip is now under his belly.

“With horses, you really need to have the microchip embedded into the muscle or the nuchal ligament where it’s far less likely to roam more than a few centimeters,” Wulf said. The nuchal ligament is a thick ligament located along the top of the neck, spanning from the poll to the withers.

Even so, muscle growth can cause the chip to end up deeper below the skin surface as the horse grows, and this can cause readability issues with certain kinds of scanners.

Basic scanners usually have a c