A week before the AQHA World Championship Show, Buck Oak was the picture of health. • Photo by Chelsea Schneider

Lyme Disease: A Pinpoint Diagnosis

Chelsea Schneider was mad. After showing her 5-year-old buckskin gelding to two firsts and a second in a halter class earlier that day, the pair was called out of the class for lameness in the afternoon. The horse trotted fine on the concrete, and had not shown any signs of being sore after the three reining schooling runs completed that morning. 

Calming down, Schneider called her trainer and boyfriend, National Reining Horse Association professional Garrett Gentry, to relay the news. Gentry didn’t believe the horse could be that sore, that fast, and suggested Schneider get him back out to test him. 
“I trotted him on the arena dirt and he was sound, then on the concrete he was lame,” she recalls. “Back to the dirt and he was lame, then sound when on the concrete again. It was minutes apart that it was changing. I had never seen anything like it before—a horse is typically lame or it’s not. It didn’t make sense.
“The next morning, he trotted out sound, so I saddled him to ride. When I got on, he was three-legged lame. I loaded him up and took him home.” 
From there, Gentry said, it all went downhill. Shine Oak Shine, called “Buck Oak,” would be treated for a systemic infection before being diagnosed with Lyme disease. The course of treatment wreaked havoc on the horse, and created a worrisome situation for his owner and trainer. 
Though recovering today, Buck Oak is a classic case of a horse living with Lyme disease. And these cases are becoming more frequent. 


In 1970, Lyme disease was identified in Lyme, Connecticut, hence the name. It is a vector-borne disease, meaning it is transmitted from host to victim and cannot survive long outside the host. Most commonly identified with tick bites, the disease has been reported in the majority the United States. 
The 2015 map of USDA Centers for Disease Control-reported Lyme disease cases shows a heavy concentration of cases in New England and the northeast. Cases stretch as far south as Florida and into the eastern Midwest, with a heavy concentration in Wisconsin. In California and Washington states, there are also pockets of high reports. 
“The hotbed of infection is in the eastern states,” said Dr. Terry Hensley, DVM, assistant agency director at the Texas A&M Veterinary Medical Diagnostic Laboratory located in College Station, Texas. “The CDC considers Texas a low risk, and that is primarily the eastern third of the state.” 
Lyme disease is an infection caused by the bacterium Borrelia burgdorferi, and can be called Borreliosis. Hensley explains that the bacteria enters the bloodstream through an infected tick bite, and the blood stream carries the bacterial organism to different body organs. The immune system tries to attack the organism. 
“Some horses can be infected and never develop clinical disease; their immune system keeps it in check,” he said. “Some horses can be infected but only exhibit clinical signs when their immune system is suppressed by another infection.”
A suppressed immune system is how Schneider and Gentry became acquainted with Lyme disease. 


When Buck Oak had to be turned around to unload from the horse trailer, Gentry couldn’t believe his eyes. One pass down the barn alley would show lameness in a front leg, the next pass in a back leg. In addition to lameness, the gelding came home with a cough. 
“We called Dr. John McCarroll to see about the cough, and he agreed to do a lameness exam at the appointment,” Schneider recalls. “The appointment wasn’t until the next Friday, so he had us start the horse on treatment for the respiratory infection.”
The top photo of Buck Oak shows the gelding weighing 1,368 pounds. In less than a month, the gelding dropped 388 pounds to weigh 980. The weight loss was shocking for Gentry and Schneider. • Photos by Chelsea Schneider
That was early January 2017, and Buck Oak weighed roughly 1,370 pounds. Less than a month later, he dropped nearly 400 pounds and had lost all interest in eating. Though being treated for a systemic infection that saw McCarroll draining between 18 and 33 ccs of fluid off the gelding’s joints, he was not improving. Gentry said that when McCarroll said he wanted to try something else, they jumped at a possible solution. 
“He went to thinking outside the box and treating Buck Oak for Lyme disease,” Gentry said. “We did draw a blood sample and sent it to Cornell University for a tick screen. It came back negative. The one we did was a basic one. Throughout this journey our vet bill had grown significantly. There are more precise tests, but we were already seeing improvement treating him for Lyme, and we decided not to test and do something that answers our obvious question.” 
Soon, Buck Oak was on doxycycline and showed interest in his feed. The horse had developed abscesses in his windpipe, making it difficult to breath, so he was also being treated with a nebulizer, which administers care to the respiratory tract. 
For Schneider, it felt like her horse was coming back from certain death. 
“I’m not much of a Facebook poster when things go wrong with my animals, but in February, when things started to get better, I posted a picture of Buck Oak wearing a nebulizer,” she said. “My inbox blew up.”
Contacts around the country soon flooded Schneider’s inbox with their own tales of horses that had battled Lyme disease. Small changes in Buck Oak that Schneider and Gentry noticed in September of 2016 suddenly began to make sense. 


Described as a saint of a horse and friendly to a fault, Schneider’s gelding began to show signs of crankiness when being blanketed in September 2016. Gentry and Schneider were pointing the horse at the National Reining Breeders Classic and then had their sights set on the American Quarter Horse World Championship Show in November. 
“He started to turn away like he didn’t want us to put it on. It was not like him at all,” Schneider said. “We were riding him hard and just thought he was cranky. We gave him time off, but the crankiness never went away. Garrett had a job offer to go work for Tom McCutcheon, so after the world our horses had time off and he didn’t get ridden again until January 1.” 
Shortly after, the shifting lameness appeared at the horse show and Schneider’s nightmare began. Looking back, the horse displayed early clinical signs of Lyme disease by exhibiting hypersensitive skin. 
Hensley explained that is one of the most common clinical signs. 
“Lyme disease exhibits a lot of signs that can be attributed to other conditions. A lot of horses will exhibit stiffness or shifting leg lameness—in the right one day and the left another—and that is common; increased skin sensitivity to touch is a common sign, and some of them are lethargic,” he said. “People will note a letdown in the horse’s performance, and that may be one reason it is diagnosed in more sport-type horses because of the drop-off in their performance level.”
The disease can also mimic Equine Protozoal Myeloencephalitis, commonly referred to as EPM, and unless the horse displays clear clinical signs directly related to Lyme, can make for difficult diagnosis. 
Diagnostic laboratories like TVMDL and the Animal Diagnostic Center at Cornell University in New York offer serologic tests to measure the titer level of a disease, which can speak to the animal’s exposure. Titers measure antibodies, and the higher the titer the more antibodies found in the patient’s blood. 
“The antibodies can be a result of infection, exposure or vaccine. As of right now, there is not an equine vaccine for Lyme disease,” Hensley said. “[TVMDL] tests by immunofluorescent assay and Cornell offers a test to measure the different types of antibodies—outer surface proteins—to determine between chronic and newly infected animals.”
The close relationship between trainer Garrett Gentry and Shine Oak Shine deepened during the horse’s illness and recovery. • Photo by Chelsea Schneider
Cornell’s test is a multiplex test that looks at outer surface proteins (OSP) that are on the Borrelia burgdorferi bacteria. The test is able to distinguish between OSP-A, the type in the tick; when the tick is feeding, the organism changes to OSP-C, and then when it has been in the mammal several weeks or months, it changes to OSP-F. This test is not only used to diagnose the disease but can be used to gauge recovery. 
“Lyme seems to be only transmitted through a bite, at least that is what the studies show. There is not any scholarly evidence that shows direct infection as a result of mice droppings, though mice can harbor the bacteria and serve as a source of infection for feeding ticks. Only certain species of ticks are involved in the transmission of Lyme disease,” Hensley said. “The tick feeds on the mouse, gets infected, and passes the infection on to the dog, horse or human it bites. The only proven transmission method is a tick.”
However, neither Gentry nor Schneider ever found evidence of a tick biting Buck Oak. Both believe the gelding was exposed and infected at his previous training facility, in Grandview, Texas, in 2016. Gentry described the facility as being surrounded by farmland, which made it hard to control the field mice in the area.   
“Through our connections and our research, we think most horses in a stable environment are being infected by mouse feces,” Gentry said. “Chelsea and I are horse lovers and would go over every inch of that horse when we got him out. We never found a tick.”
Yet Buck Oak responded to the treatment of choice for Lyme, which is a long-term course of doxycycline or tetracycline. By early April, the horse had gained some weight back and was showing less obvious signs of infection. 


In late April, Buck Oak started back under saddle, with Gentry working him slowly and using the McCutcheon’s aqua tread swimmer to assist in building endurance and muscle. The horse was on a continued treatment of doxycycline and a nebulizer to help heal his throat. 
Buck Oak was treated with a course of antibiotics. Long term antibiotics led to stomach ulcers and throat abscesses, which the nebulizer aided in healing the gelding’s respiratory problems. • Photo by Chelsea Schneider
“One of the big things with Lyme is hypersensitivity to hot or cold water, and they will stamp like they are being attacked by flies when there are none,” Gentry said. “He will still stamp his feet while at his feeder.” 
In the long run, Schneider and Gentry both believe Buck Oak will be back in the show arena. 
“If he doesn’t ever show again, I own a pet for the next 20-something years, and that is what we will do,” Schneider said. “We are his owners and he looks to us to care for him.” 
However, the contacts that Gentry and Schneider have across the country are examples of horses living and competing in spite of battling Lyme disease. Hensley agrees, stating that it is not a death sentence.
“Horses can have chronic lameness and sensitivity problems from Lyme, but it can be treated,” Hensley explained. “The success rate revolves around a recent infection versus a chronic infection once treatment gets started.” 
For Buck Oak, his case was caught fairly close to when he showed the most common signs of infection. Even then, it was a trial for those closest to the horse, and one they passed with flying colors. 
“While I’m not glad we had to go through this, I am thankful we were able to broaden our education to make us better horse owners and better caretakers,” Schneider said of the ordeal. “The advice I would give to other horse owners is to educate yourself through research and ask questions any time you can. If you know deep down there is something wrong, pinpoint the cause of the problem. We were fortunate to have a veterinarian that thought out of the box to help the horse.”