PLATTSBURGH, N.Y. — Sophie Macner knew Hazel wasn’t acting like herself.

For nearly three years, the teen from Plattsburgh, New York, and her horse had trained on a regular basis. The two had placed well during the 2014-15 4-H horse shows.

But then the 13-year-old American Paint pony had begun demonstrating a few odd behaviors. Hazel, a mild-mannered, good-natured mare, had begun shaking and flicking her head repeatedly during their rides.

“I didn’t know what was going on or why she was doing it,” Sophie said. “It wasn’t like her to behave like that.”

Hazel began to rub her forehead on whatever she could find — Sophie’s leg, a fence post, anything. The sporadic actions became distracting and difficult to manage.

By August 2015, Sophie stopped riding Hazel altogether.

Intense pain 

In January, Hazel was diagnosed with trigeminal nerve neuralgia, or TN. Studied extensively in humans, TN produces regular bouts of intense facial pain. 

Only within the last decade have veterinarians discovered the rare disorder affects animals, too.

Sophie’s mother, Sharon, said that getting Hazel properly diagnosed was a long, difficult and stressful process. For months, they struggled on their own to understand the mysterious symptoms.

Admittedly not a “horse person,” Sharon began to ask questions of those with more expertise in the matter. Initially, she was told that Hazel was being “bad” and that Sophie needed to correct the horse.

“The first instinct is to correct the (horse’s) behavior,” Sharon told the Plattsburgh, New York Press-Republican. “It was quickly apparent that you couldn’t correct this behavior. And when you tried to correct the behavior, it got worse.”

Symptoms persist

The Macners were referred to veterinarian Dr. Toby Pinn at the Vermont Large Animal Clinic and Equine Hospital, about 30 miles east of Plattsburgh.

The vet ran a series of tests on Hazel, followed by various treatments. A nose net was used to limit the amount of external stimulus the horse received and, when that didn’t work, Pinn prescribed medication.

The mare’s symptoms persisted.

“There became a suspicion that Hazel was demonstrating signs of trigeminal nerve neuralgia,” said Sharon.

When a “block” was placed on Hazel’s trigeminal nerve, her symptoms disappeared. The disorder diagnosed, they now needed a workable treatment.

“Without treatment, humans with this condition generally deteriorate,” Sharon said.

“They endure bouts of severe pain simply by swallowing, smiling or breathing. It’s a very difficult condition to treat.”

Electrodes

Pinn put the Macners in touch with Dr. Norm Ducharme at the Cornell College of Veterinary Medicine in Ithaca.

Ducharme had successfully implanted pacemakers in horses with recurrent laryngeal neuropathy, a condition that causes a progressive destruction of the nerve supply to the muscles of a horse’s larynx. 

The pacemaker, which is surgically implanted in a horse’s throat, uses electrical stimulation to mimic the work of damaged nerves.

“(Dr. Ducharme) proposed a highly experimental surgery on Hazel in which electrodes would be implanted directly in contact with her trigeminal nerves,” said Sharon. 

“This was a dream situation, having a horse with signs that were obvious, repeatable and constant,” Ducharme said. “And you have someone who knows these (electrical stimulation) units because of their background.”

Sharon had faith in the procedure, but there were still the risks.

“This was a hard conversation for our family about whether to proceed,” she said. “We told Sophie, ‘We don’t know if this is going to work, and this is a large investment.’ 

“Initially, we said no.”

One of a kind

In May 2016, Hazel became the first horse in the world to receive an electrical stimulation unit implant to reduce the symptoms of TN.

Hazel remained at Cornell’s equine hospital until she could be trailered to a stable near the Macners’ Plattsburgh home. Since the surgery was one-of-a-kind, the treatment by Sharon and Sophie would be by trial and error.

The nerve stimulation unit consisted of three quarter-sized electronic processors. One was implanted in a natural cavity in Hazel’s forehead. The remaining two are external and act as transmitters delivering various milliamps of electrical stimulation.

Sharon’s job is to adjust the electrode settings, place the magnetic-equipped processor squarely on Hazel’s forehead and take notes on the horse’s response. It is a tedious, “learn as you go” process.

“I have to be slow and steady to figure out the stimulation (level)” she said. “How frequently do you apply the stimulation? How often? It’s going to take time to get the right process.”

Ducharme agreed.

“It will take a few years and many, many more horses (to claim success),” he said. 

“We need to know a range of response. It will take us three or four years to figure out how long each treatment lasts or if there are any side effects.

Best friend

Sophie thinks back to the Hazel she knew before this all happened.

“I’ve always admired Hazel for the well-mannered and talented pony that she is,” she said. “I’ve never met a horse that I have loved as much as her. 

“The surgery was really important to me because I didn’t want to lose my best friend.”

Langlois writes for the Plattsburgh, New York Press-Republican.