It has been nearly two years since the first crop of Thoroughbred foals received microchips at the requirement of The Jockey Club as the group sought better, more reliable identification for horses on and after the track. But while next year's 2-year-olds will head to U.S. racetracks with a tiny chip implanted in the nuchal ligament on left side of their necks, some Canadian Thoroughbreds are getting theirs in a different place.
When discussions about the best way to microchip horses first began, Adrienne Herron listened with interest. A livestock extension specialist with research experience in animal behavior, Herron thought the neck location for a microchip less than ideal.
For one thing, it might require handlers to climb into stalls or trailers to reach the midline of the neck for a scan – something that may be intimidating to less experienced handlers or security personnel. It also seemed like a slightly uncomfortable option for the horses, who may be mistrustful of a long wand reader coming too close to the blind spot right behind their heads.
Then, in the early days of microchipping, it would require health officials to actually find the thing.
“My experience with nuchal ligament is they're often located anywhere from just behind their ears to all the way down by their withers,” said Herron, who has worked as a traceability expert for the government. “I've found them migrated all the way down to the base of their neck. I've had them on the off side. In a performance horse situation, I've come across horses that have three or four microchips implanted because of the depth of the implants — people with a smaller reader wouldn't be able to read them, so then a vet would assume they didn't have one and put another one in.”
Herron heard of one case where a chip had actually migrated down to the coronary band on a sport horse. It was discovered inadvertently by a veterinary tech just before another chip was about to be inserted.
Microchip placement hasn't been studied extensively in horses, but Herron cited one report which found 50 percent of horses with microchips did not have them placed in the nuchal ligament as originally intended, but in muscle or fat tissue, possibly because the nuchal ligament can be a little tricky to locate.
Of course, microchip technology has improved considerably in the past several years. Herron said more companies (including the one contracted by The Jockey Club) use biocompatible plastics, which the body recognizes as normal tissue. Muscle and other tissues tend to grow around these chips, anchoring them in place more completely than the glass chips of bygone days.
Still, Herron wondered if there wasn't another possible chip location – underneath the horse's upper lip.
“I'm a behaviorist and have grown up with horses my whole life,” she said. “Horses have that curiosity where they're nosy and constantly investigating novel objects with their nose. I had the idea it might be a more behaviorally-appropriate location for an implant.”
Four years ago, Herron started a pilot project to see whether microchips could be implanted into the nasal labial tissue of the horse. Some 6,000 horses later, she said she's confident this implantation site solves a few problems.
Based on Herron's work, the Canadian Thoroughbred Horse Society released guidelines in 2016 suggesting its members have their horses microchipped under the upper lip, around the midline of the lip. This is now the only location the CTHS suggests.
One of the first reactions Herron said she gets when she talks about implanting microchips under the upper lip is whether horses will tolerate the process. In the several thousand she's implanted herself, she hasn't encountered any serious problems, despite working with horses in various states of handling.
“The response from the vet community has been really interesting,” she said. “There's a lot of pushback until they see the procedure performed, and then there's a lot of lightbulb moments.
“The horse's behavioral response to having the upper lip lifted is they always step backwards. They don't come in to me, and they don't rear or strike.”
She's also gotten questions about post-implantation side effects. Unlike nuchal ligament chips, which she has found anecdotally may cause neck stiffness in some horses in the days after implantation, she has seen no ill effects in horses getting the chips under their lips. That includes implantation site infection. Herron said oral skin tissue in mammals is non-scarring, and saliva has anti-bacterial and anti-fungal properties which she believes keep infection away.
While some people may worry about attempts to remove a microchip from a lip, Herron said that's unlikely. Registered Thoroughbreds will still have DNA samples on file to verify identity, so attempting to remove a microchip (which would be difficult since they're so small) wouldn't do much to obscure a horse's identity permanently.
The other big concern for veterinarians seems to be the possibility of disease transfer. Herron said some veterinarians and health officials have better microchip readers than others. While a good chip reader doesn't need to touch the horse's nose to read the chip, it would need to get near it.
“Anything that's near their mouth is problematic from a respiratory infectious disease standpoint,” said Dr. Rob Holland, managing partner of Holland Management Services Consulting and veterinary medicine team lead outcomes researcher at Zoetis.
“One of the things we were worried about in the equine herpes outbreaks recently was the horse identifiers because they would flip the lip of every horse and take a rag to wipe off the lip to read the tattoo number. We actually thought that could be a real problem. We asked during the outbreaks that the groom flip the lips and the identifiers wear gloves or something like that. We thought a device that goes from horse to horse could be problematic.”
Holland said there's a lot we still don't know about disease transmission in horses, but we do know shared items, called fomites—hands, rub rags, halters, buckets—are a concern during an outbreak. Studies suggest equine influenza can live up to two days on contaminated surfaces and three days in water. EHV-1 is stable in water and can live there for up to three weeks. In one study, Streptococcus equi was found on a fence post three to five days after being placed there, and in water for up to a month.
Herron admitted the chip readers are one more potential surface for disease concern, but she isn't sure they're going to make the difference in an outbreak.
“When you watch the lip tattoo reading guy [at the racetrack], he doesn't wash his hands in between horses,” Herron pointed out. “My personal opinion is the majority of racetrack barns are one premises. If you have an infection in a barn, how often is it that the entire racetrack ends up with a respiratory infection? Between tack sharing and riders there are so many other factors.”
When reading chips at the track, Herron suggested identifiers disinfect readers between each training operation.
Holland remains concerned about sanitizing procedures because it's hard to get people to follow protocol until there's already a problem.
“The problem is, that's not what happens in the field,” said Holland. “We have many men and women that are great with horses but they use the same rag to wipe the nose and lips of the horse…and then they go right to the next horse and it's like, ‘Oh…that's not a good idea.'”
It doesn't appear The Jockey Club (which Herron said is fully aware of her research) is going to change its microchip location guidelines anytime soon, however.
“Microchips became a requirement of foal registration with the 2017 foal crop,” said Shannon Luce, spokeswoman and director of communications for The Jockey Club. “Based on consultation with international stud book colleagues, including Great Britain, France, and Australia, The Jockey Club recommends that microchips be implanted under veterinary supervision in the middle third of the neck in the nuchal ligament on the left side of the horse. For convenience, any reported deviation in the implantation site will be noted in the markings section of the registration certificate.”
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