Stallion Showcase 2023: DNA may help diagnose Lyme disease in horses  |

Stallion Showcase 2023: DNA may help diagnose Lyme disease in horses 

Native to just about every state in the U.S., the all-too-common, always unwelcome tick finds its way into comfy places on both horses and humans. Even though a blood-sucking attachment is gross on its own, the disease-spreading component is the larger concern.  

With a wide variety of tick-borne diseases to be aware of, finding a tick is a bit concerning. While Lyme disease isn’t the most common in the Midwest, it’s arguably the most detrimental.  

“It’s not a common disease but that might be because it’s so hard to diagnose,” said Dr. Dallas Shaw a veterinarian at 88 Equine in Buffalo, Wyoming.  

Location, Location, Location  

According to the Center for Disease Control (CDC), incidences of Lyme Disease in both horses and humans is mostly concentrated in the northeastern region of the U.S. Perhaps that’s why Steven Schutzer, a professor of medicine at Rutgers New Jersey Medical School, helped devise a special DNA test to identify the disease. * 

“This new test might be easy to run and cheap, but collecting the sample of cerebrospinal fluid is neither of those things,” said Dr. Kyre Larrabee, who is a veterinarian in Gray County, Texas. “You can collect this sample from either an area near the poll or in the lumbar sacral region.”  

Collecting from the poll area requires laying the horse down and putting them under general anesthesia. While the second location can be done with the horse standing, they still need to be heavily sedated.  

“If a horse is already showing severe neurological signs, then they probably aren’t a good candidate for anesthesia,” Dr. Larrabee said. “Collecting cerebrospinal fluid is a risky procedure, both for the safety of the horse and veterinarians during collection as well as for secondary infection in an extremely vulnerable place.”  

Right now, standard procedures for diagnosing Lyme disease in horses begin with ruling everything else out first and usually ends with starting preventative antibiotics.  

“Even in human medicine, some doctors may begin treatment as a presumptive measure,” Dr. Larrabee said.  

The Deer Tick 

“The bacteria causing Lyme disease [Borrelia burgdorferi] is really smart and adapts quickly through the immune system, which is why it’s hard to detect,” Dr. Larrabee said. “Lyme disease can go under the radar for a very long time before it’s discovered.”  

Carried by the deer tick – Ixodes scapularis – Lyme disease is picked up by the tick during its life cycle when it attaches to various wild mammals, like small rodents and deer. 

“If a tick attaches itself to an infected wild animal, like deer, they may not show any signs of illness but for horses and humans, we are considered dead-end hosts,” Dr. Larrabee said. “Luckily, it takes about 24 hours of attachment for the tick to transmit the disease.”  

That is why doctors recommend checking yourself and horses for ticks daily. Prevention is the best medicine almost always, but especially in the case of Lyme disease.  

“There’s no vaccine for horses yet, but there is one being used for dogs that’s been effective at preventing the disease,” Dr. Shaw said. “Regular grooming and keeping your animals out of places where ticks like to live is the best advice for preventing this disease.”  

Mowing taller grass and trimming back trees is an efficient way to cut down on ticks. Dr. Larrabee also added that chickens can be helpful because they eat ticks.  

“Knowing how to remove a tick is also important,” Dr. Larrabee said. “You want to use tweezers and grasp as close to the attachment as possible. Don’t squeeze too hard though because you don’t want to leave any mouth parts behind in the skin.”  

Contrary to what we grew up doing to remove and kill ticks, the best option is to seal the tick inside a plastic bag with some form of liquid, like alcohol or a household chemical.  

“Dropping them in alcohol is a quick way to kill a tick and you’ll want to rub alcohol on the area where you just removed them,” Dr. Larrabee said. “You don’t want to crush them with your fingers or get any of the blood on you because it could be diseased.”  

Rutgers’s DNA Test 

“The unique part about the DNA test is they made a hybrid capture by isolating specific DNA from the bacteria,” Dr. Larrabee explained. “It’s a pretty neat study. And if you have a horse that’s showing a lot of neurological signs this test would potentially diagnose active Lyme disease as the culprit a lot faster than what we use now.”  

The practicality of collecting cerebrospinal fluid doesn’t outweigh the benefits of a fast diagnosis in the Midwest where Lyme disease isn’t at all common.  

According to the CDC, reported cases of Lyme disease in humans in 2019 was highest in Pennsylvania at 6,700 cases. The same year, South Dakota reported seven cases and Wyoming had two incidences.  

“Testing through DNA like Rutgers did is important because Lyme disease is zoonotic,” Dr. Larrabee said. “It’s something to always have in the back of your mind, no matter where you live, because it can happen anywhere at any time and early diagnosis can prevent a lot of headaches.”   

*To read the full article about this study on a novel DNA test for Lyme Disease created by Schutzer, visit: