The Horse Who Went “Harumph”
Equine Tourette’s Syndrome
A good rider can hear his horse speak to him. A great rider can hear his horse whisper.
There’s a little joke we veterinarians like to tell: What do you call a vet who treats only a single species? Answer: a physician.
Yet we also like to say that we veterinarians treat people as much as we treat animals. Because, as much as my work is to fix animals, it’s an important part of any veterinarian’s job to give relief to owners who are worried about their pets.
Emily “Mimi” Edwards called me from Connecticut to discuss possible treatments for her Arabian stallion, Migdol, a valuable show horse who had won a number of prestigious competitions. Unfortunately, when away from the show ring, this beautiful horse suffered bouts of repetitive spinning and squealing. Most upsetting, he bit through the skin of his legs and flanks until they were raw. Mimi was upset by her horse’s distress.
I couldn’t diagnose the problem over the phone and, at this early stage of the discussion, bringing Migdol to Tufts was impractical. So my colleague Lou Shuster and I agreed to travel to Mimi’s stable in Connecticut.
As we drove, we wondered out loud about Migdol’s symptoms. Clearly, Migdol had some kind of repetitive behavior disorder. But was it a stereotypy, the kind of mindless “stall vices” we had encountered in our previous studies? Or did the behavior have a medical cause?
If it was a simple stereotypy, it was possible that the underlying mechanics were the same as cribbing. But that didn’t quite make sense, since the symptoms were so different. The behavior was repetitive and seemingly pointless, for sure, but it was also unlike any of the common stereotypies that I was aware of at the time. Fortunately, Lou and I had remembered to take along opioid antagonist medication, just in case Migdol’s behavior was, indeed, some type of stall vice.
When we arrived, Mimi led us to a dimly lit barn, where, in the farthest, darkest, dankest corner, stood Migdol. The extremely handsome light bay Arabian stallion wore a wire muzzle with a series of vertical metal bars to prevent him from biting himself. He resembled an equine Hannibal Lecter in The Silence of the Lambs. For added protection, in case the muzzle slipped off and he attempted to injure himself, a thick cover that looked like an oversized raincoat was draped across his back and secured under his belly with ties.
Mimi gently lifted up a corner of Migdol’s blanket to reveal his scars. They were an upsetting sight. Patches of hairless, exposed skin showed where he’d bitten himself. Healed and semi-healed teeth marks pockmarked his flank. As Mimi was showing us his injuries, Migdol became highly animated. He began prancing around the stall and kicking out with his hind legs, causing us all to retreat.
“He’s having an attack right now,” Mimi said.
Migdol started whirling around in tight circles, glancing and jabbing in frustrated attempts to reach his brisket and flank, kicking out with his rear legs. His hooves striking the wooden walls of the stall boomed like thunder. This whole fit was punctuated with snorts, head shaking, and occasional sniffing of the ground.
After a few minutes Migdol quieted down again. Lou and I had never seen such behavior and we hoped that one of the medications we’d brought with us could give him some relief.
Mimi led Migdol into a larger space, an indoor arena attached to the stable, which had an observation box for trainers and spectators. She gently held the stallion’s head while I gave him an injection of saline into the jugular vein. Lou and I then headed to the observation box, clipboard and score sheet in hand to count the minutes that elapsed before any change of behavior occurred.
At first, Migdol ran and pranced around the periphery of the indoor arena, seemingly enjoying his newfound freedom. After a few minutes, however, he displayed another bout of whirling and kicking. Almost midstride, Migdol started to buck and simultaneously kick out with his hind legs, squealing and pivoting all the while. That first attack was over in less than a minute.
Migdol resumed trotting around and exploring. After a while he slowed to a walk and started to sniff the sawdust-covered floor of the arena. A pile of horse manure attracted his interest and he spent a while investigating it. Then he suddenly exploded into another intense bout of spinning and trying to bite his own flank.
Our score sheet soon became covered with notations. The first two hours featured forty or so of these attacks, of various intensities and durations. Some bouts were perfunctory, while others were alarmingly severe.
At the two-hour mark, we had Mimi catch Migdol by his head halter. This time Lou held him while I injected an opioid antagonist called nalmefene. The drug has qualities similar to the naloxone that we’d used on cribbing horses, except that its effects last longer.
After we gave him the injection, we released Migdol back into the open arena. For the next two hours, as the nalmefene coursed through his blood and into his brain, Migdol showed no bizarre behavior at all. It seemed as though the nalmefene was effective on Migdol’s condition, just as it had helped stop other horses from cribbing. But though we had a successful treatment, we had no diagnosis. Since we still didn’t know what precisely Migdol was suffering from, Mimi agreed to bring him to Tufts, so that we could study him further.
The following week, when Migdol arrived at Tufts, we discovered something new about him: Migdol hated thresholds, doorways, or any transition from one environment to another. Getting him out of the trailer was our first challenge. Mimi finally managed it, even though Migdol reared, balked, squealed, and kicked throughout the whole process. Then, as she led Migdol through an arch leading to a large foyer, the stallion went crazy again, rearing and bucking and spinning around. This happened every time he went through a new doorway on his way toward his temporary stall.
Once Migdol was in his new quarters, he dashed back and forth, bucking and twisting, snorting and kicking. He then was calm for a few minutes, momentarily sniffed the ground, and began the whole upsetting display over again. During these attacks, he also attempted to bite himself, clacking his large incisor teeth close to his brisket, chest, or flank. Some of these attempts were accompanied by a strange harumphing sound. The cycle was continual. Although we did not observe him through the night, we assume this went on then, too, as horses don’t sleep through the night as some animals do.
As we watched him the first day, Mimi told us about Migdol’s heritage. Both sire and dam had similar problems, although Migdol’s sire settled down once he was castrated. Migdol’s half brother also displayed the same behavior. Sadly, that horse had to be euthanized after he kicked a wall and broke the pastern bone in his foot. The bloodline heritage was a pretty clear marker that Migdol’s condition had a genetic component.
Migdol had started striking out and trying to bite himself when he was eighteen months old. The problem fluctuated over the years. His attacks were less severe during seasons when he was extensively bred. They worsened when he was given a season’s rest from breeding. Being able to breed seemed to quench his fiery behaviors, while sexual frustration appeared to fan the flames.
In the stall, between Migdol’s attacks, we repeated the saline control and, after an appropriate amount of time, injected the nalmefene. After the drug injection, Migdol almost immediately settled down, wandering back and forth and picking up occasional pieces of hay to nibble. The calming effects of the medication lasted about four hours, after which Migdol gradually returned to his familiar distressing behaviors.
Now that we had replicated the results from our trip to Connecticut, we conducted a four-day “dose-ranging” study. We progressively increased doses of the medication to see how long each dose’s helpful effects would last. The doses ranging from 100 to 800 milligrams of nalmefene reduced Migdol’s flank-biting attempts linearly. In the control period, after the saline injection, he suffered eighty bouts per four-hour-observation period. The frequency of self-mutilation decreased with increasing doses of nalmefene, and was virtually abolished with the 800-milligram dose.
Virtually abolished, but not quite. The score at the 800-milligram dose might have been an actual zero if we hadn’t subjected Migdol to an ultimate challenge. Toward the end of the four-hour test period, we led a mare in heat past his stall. This mare “flyby” caused Migdol to attempt four desultory flank bites. As soon as the mare was gone he resumed his tranquil state.
Though Lou and I were not the first to observe flank biting in Arabian stallions, we were the first to uncover a suspected mechanism. A prior textbook report suggested that it was specific to stallions of this breed. The condition was either propagated by endorphin release or—as we later would come to believe—excessive glutamate activity in his brain. Probably the most important neurotransmitter for normal brain function, glutamate is a nerve cell messenger and it affects nearly every part of the central nervous systems. But when glutamate keeps stimulating nerve cells over a long period of time, it causes damage, as prolonged overstimulation is toxic to nerve cells. So a high level of stress is damaging to the neurological system as well as to psychological well-being!
In any case, we had discovered the rudiments of a treatment that might one day help afflicted horses. But opioid blockers were too short-acting and too expensive to use as a daily medication, so we needed to offer other ways to modify Migdol’s behavior. We advised Mimi to give Migdol as much freedom and exercise as possible. She should either castrate the stallion or use him more consistently at stud.
Castration was not viable, since Migdol was a valuable breeding stallion. The prospect that the horse’s distressing condition might be passed on via breeding did not deter Mimi, though, in fairness, the hereditary nature of the condition has not been conclusively proven. Once the stallion returned to Connecticut, the measures Mimi was able to implement did seem to help. Migdol still engaged in the distressing behavior, though at a slightly reduced frequency and intensity.
A few months after we’d worked with Migdol, a horse owner from Michigan, Jo Anne Normile, sent along a letter and a video that told the story of her American quarter horse, Dan the Man. This beloved horse had engaged in flank biting to such an extent that he became emaciated, failed to thrive, and ultimately had to be put down.
None of the equine experts Jo Anne had contacted had been able to give her a straight answer about what had caused Dan’s issues. Some said it was likely a result of a skin condition. Others suggested he had “sand colic,” which occurs when a horse ingests sand as he grazes. Still others argued that stallions who behaved this way were simply sexually frustrated. A detailed postmortem performed at a veterinary school ruled out a medical condition—at least one for which any tests existed.
The videotape Jo Anne sent me began with Dan being borne into her waiting arms. You could see the look of wonderment and love in the new owner’s eyes. She and the horse grew to be exceptionally close. Dan became like a son to her. Even after the poor horse died, Jo Anne still looked for answers to his torment. She had dedicated her life to finding a diagnosis and a cure for his condition, and she wanted to enlist our help at Tufts.
The video record displayed the wretchedness at its very beginning, when Dan was about nine months old, shortly after he was castrated. Initially, he was just bucking and kicking more frequently and at first Jo Anne thought he was trying to escape from biting flies. But the behavior quickly progressed to flank biting, head shaking, and snorting that Migdol also engaged in. When the video showed Dan twirling in circles, biting his brisket and flanks during a midwestern winter with snow falling, the biting-fly theory was effectively ruled out.
The local vet tried to help Dan but, though some of the treatments were temporarily successful, the problem always returned at full intensity. Finally, Dan’s constant misery and tremendous weight loss precipitated Jo Anne’s painful decision to have him euthanized.
Jo Anne, Lou, and I decided to create a survey reaching out to other horse owners who might have experienced similar issues with their own stock, in order to find out how widespread this condition was and learn more about it. The three of us sat down to sketch out a series of questions regarding the odd, repetitive, self-harming behaviors of Migdol and Dan the Man. Jo Anne sent the survey to horse owners across the country and, in a few months, received scores of responses.
When we collected the data, we found that, far from being limited to Arabians, the condition affects all breeds of horse. It strikes males more frequently than females, but can affect either sex. The attacks usually begin when horses are young, and the average age of onset was eighteen months. The survey also showed that some affected horses made bizarre noises while engaged in the behavior. Harumph was the description of the sound given by more than one owner. One outlier response reported a horse that first exhibited the behavior at thirty-two years of age, after an accident. The flank biting had started after the horse had reared up, flipped over, and concussed his head on a rock.
Castration had a palliative effect on some stallions. No other medical treatment was reported to be particularly effective.
Jo Anne, Lou, and I all read widely in the medical literature about self-mutilation and tic disorders in humans. Jo Anne was particularly intrigued by references to Tourette’s syndrome, a condition in which people sometimes shout inappropriately and make sudden motions or gestures. Samuel Johnson, the famous intellectual and author of the first English dictionary, had Tourette’s. Johnson would whoop and gesticulate on crossing thresholds. Only those who knew him took it in stride. She highlighted the many similarities between Tourette’s syndrome and flank biting in horses.
Symptoms of Tourette’s syndrome in humans and the parallels with the equine condition we found include:
• Occurs mostly in males, as does the equine syndrome;
• Responds to chemical castration, which is effectively the same as surgical castration of horses;
• Arises in children of around seven years of age, the equivalent of eighteen months in a horse;
• Causes about 10 percent of affected persons to vocalize inappropriately, similar to the harumphing sound we had noted;
• Can cause hemiballismus, a fancy name for large involuntary movements of the limbs, such as the sudden striking out with an arm or leg;
• May cause repetitive sniffing;
• May cause head and neck motor tics, consisting of sudden jerking movements.
The last three behaviors all occurred in our surveyed horses. Some Tourette’s sufferers also reportedly have trouble crossing thresholds, the same quirk displayed by Migdol. People with Tourette’s syndrome sometimes unintentionally act out aggressively. For instance, they may act as if they are going to punch someone before suddenly stopping short. Likewise, normally harmless affected horses can appear as though they’re going to attack. Afflicted people are often found to have above-average intelligence, and that was often how owners described their horses in the survey responses.
Signs of Tourette’s syndrome are exacerbated by stress, as well as sexual thoughts and connotations. Again, there were obvious equine parallels, this time to the stud activity (or lack thereof) and frustrated desire in horses such as Migdol. Clinical signs of the syndrome usually dissipate when affected people are engaged in an absorbing activity, just as horses tended to cease the behaviors while working or running.
With all these parallels, Lou, Jo Anne, and I were pretty sure we had found an animal equivalent of Tourette’s syndrome. People with Tourette’s frequently have coexistent obsessive compulsive disorders, so Lou and I thought that we might be able to treat horses like Migdol and Dan with the same drugs we’d used for treating compulsive behavior in other animals. We wanted to use a drug that damped down naturally occurring brain neurochemicals that we postulated were somehow being overproduced. The overproduction and release of naturally occurring neurochemicals in specific brain regions is also thought to be involved in propagating Tourette’s syndrome. Abnormal opiate receptor function has been demonstrated in people with Tourette’s, and some sufferers have shown at least a partial response to treatment with opioid antagonists.
It was time to reach across the species barrier. Lou and I sent the Tourette’s Syndrome Association (TSA) a video of affected horses. We described the common features of human and equine Tourette’s syndrome, though we didn’t know how our comparison might be received. The response might very well have been one of disgust and anger. People are not horses, sirs!
We were instead pleasantly surprised. The TSA agreed to fund a research project on the equine condition. Here was a chance to help horses and perhaps shed light on a human condition that bedeviled and distressed many people. At Tufts, Lou and I prepared our “laboratory,” a stall at the large animal hospital with an observation window. We affixed a camera to the wall that was connected to a television monitor and video recorder. We also cushioned the walls with two-inch-thick pads, in order to prevent injuries to the horses.
We tried several different medications on nine horses who we believed were suffering from the equine equivalent of Tourette’s syndrome and found the improvement with each one extremely compelling. It mirrored what we knew about the response of human Touretters. Even apart from the videos and notational data, by the end of the experiment we had a striking visual demonstration of the extremity of the problem. Our pads had been completely trashed. The stuffing had been literally kicked out of them. The nine horses with equine Tourette’s syndrome had hacked them to pieces in a matter of weeks.
One of our subjects actually kicked out the observation port while Lou and I were taking notes. The window had three-quarter-inch iron bars on the stall side and safety glass behind that, but it was no match for the power of a horse’s kick. Perhaps this was a particularly vigorous example of patient feedback, but it certainly had us cowering under the assault.
During the study, a crew working with a national magazine came to make a film about other experiments we were conducting. It happened that several of the TV crew members suffered from Tourette’s syndrome, including the director Scott Handler.
I told Scott that I’d noticed that when two Tourette’s syndrome horses passed each other in the stable, they would pause and touch noses. This greeting seemed to calm both animals. They expressed interest in each other for a while, almost as if they knew they had the same affliction.
Scott told me that there is often a moment of recognition when two people who have Tourette’s syndrome meet. So saying, he walked up to one of the study horses and put his face to the bars. The horse wandered over to him and breathed on him. For several long seconds, Scott and the horse both peacefully investigated each other, with not a tic or grunt to be seen or heard from either. It was a magical moment.
Migdol was one of the horses volunteered for our trial and it was good to see him again. He was still exhibiting symptoms, though their severity remained diminished. During the trial, Migdol responded well to three weeks of treatment with an antidepressant/anti-obsessional medication, showing a 50 percent decrease in his self-biting behavior.
Once back in Connecticut, Mimi kept Migdol on that medication for months, and his behavior continued to improve. Mimi removed his iron mask and took off his protective blanket. Migdol was free at last. He occasionally halfheartedly would glance at his flank, but that was the extent of it.
Unfortunately, the medication is very expensive. Eventually, Mimi stopped administering it and Migdol reverted to a modicum of flank biting, but he never did it as ferociously or repeatedly as when we had first met him. Perhaps this was because of the changes that Mimi had made to his lifestyle, or perhaps the long-term use of the antidepressant had caused some lasting changes in Migdol’s brain. Antidepressants can act as a sort of neurological Miracle-Gro, causing the development of new nerve cells in the memory center, the hippocampus, which is thought to explain at least some of the results in laboratory animals as well as people.
Jo Anne was gratified to have helped to discover the source of her beloved horse’s terrible affliction and to have aided in finding a treatment. As she had hoped, horses can now be treated for this disorder so that it doesn’t progress to the kind of grievous self-harm, physical decline, torment, and death to which Dan succumbed. For the love of one horse, many horses can now be saved.
And for the love of another horse, Pepper Belle, many people with Tourette’s have been helped. Tourette’s syndrome can be especially hard on children. Just at the time when they’re trying to be accepted in school and other social circles, along come tics and shouts and involuntary movements. So it was to our great good fortune when Willie Ferrero, the owner of Pepper Belle, a Standardbred mare, heard of our study through the equine community and volunteered to help us by enrolling “Pepper” in our study. (Pepper Belle hails from East Longmeadow, Massachusetts, so she was close enough to trailer into the veterinary school for study.) During her professional career, Pepper Belle had competed in harness races across the Northeast and was a well-established champion. Willie was devoted to Pepper Belle and not just because she was a winning horse. He had known Pepper’s mother, Cool Pat, and like Jo Anne and Dan, had been present for Pepper’s birth, after which he was completely smitten. He watched as the slippery, uncoordinated foal first tried to master the art of balancing on her spider-thin legs. He grew to become familiar with her likes, dislikes, and foibles and essentially raised the mare as though she were his own offspring.
Pepper Belle was trained as a harness racer, and she loved to run and to race. But as a young adult she started to show the troubling behavioral signs of flank biting and chasing her tail. Colic was ruled out by his regular vet, and Willie turned to me because Pepper Belle’s symptoms had become so severe that it was difficult to calm her so that she would accept the halter before races. Getting her into the starter’s stall on the track was a major project and she would sometimes refuse to enter the trailer—just as Migdol had been afraid of passing through entryways and portals.
For Pepper Belle, the antipsychotic medication Haldol and a couple of sedatives temporarily suppressed her symptoms. But none of these meds was compatible with her racing career, because they made her tired, sleepy, and disengaged. Sadly, Pepper Belle’s time as a competitor came to a sudden halt, after she fractured a sesamoid bone and bowed a tendon around the cannon bone during a race. “Bowing a tendon” means that the tendon fibers are torn and heal in a way that gives a bowed appearance to the back of the lower leg.
Since Pepper Belle was out of the racing game, Willie had the bright idea that she could help children better understand schoolmates who had disabilities and differences such as Tourette’s syndrome. If kids got the chance to spend time during school visits with a fantastic animal like Pepper, a proven winner who also happened to suffer from Tourette’s syndrome, the kids could learn to develop empathy and compassion. They might understand that a condition that makes people different doesn’t prevent them from finding something at which they can succeed. Reaching out to the Tourette’s Syndrome Association, Willie offered Pepper Belle as a mascot for their national movement.
It might have seemed an odd idea, using a horse to publicize a human condition, but to their credit, the TSA immediately saw the benefit and adopted Pepper Belle as a logo and mascot. In the effort to render Tourette’s syndrome less of a stigma, they were willing to think outside the box. The TSA established a program to use the horse in educational efforts in regional schools.
Pepper’s first appearance was at Birchland Park Middle School in East Longmeadow, Massachusetts. We all attended: Willie, his son and fellow jockey “Big John” Ferrero, Mark Levine (a representative of TSA), Lou, and I. Scores of children had gathered outside in the playground and watched as Pepper Belle paraded around, resplendent in full tack. Big John, dressed in colorful racing silks, rode behind her in a sulky, as the buggies used in harness racing are called. The two of them did a few circuits around the school’s running track and then the children were allowed to come forward to stroke Pepper Belle.
After they had spent some time with the horse, the children went into the school auditorium and Pepper Belle headed back into her trailer. Willie showed the children a video of Pepper thundering around the track, taking first place over and over again. The director of the TSA then gave a talk about how Tourette’s syndrome affects people. To complete the connection, I showed a video of Pepper Belle at our veterinary school, whirling and ticking away in one of her worst moments.
The children were impressed. This was the same horse? How could the horse attacking her own flank be the same impressive champion they had so recently seen racing and then befriended on the school’s track?
The message was intuitive and easy to grasp: Tourette’s syndrome is not to be feared or mocked. It is merely a quirk of impulse control. It is not a demonic possession that affects only the weak in spirit. Instead, it represents one aspect of the enormous diversity of expression that characterizes both human and animal behavior. The children at the East Longmeadow school didn’t need much convincing. They’d seen an animal who lived with Tourette’s syndrome and was also a successful race horse.
Pepper Belle made quite a name for herself as the mascot of the TSA. Driven by his love for Pepper and his almost religious calling to help her and other sufferers, Willie wrote a tale aimed at children, Pepper Belle. But around the time he finished his book, Willie told me that he was suffering from leukemia, a recurrence, and that the cancer had spread.
“It’s in my chest now,” he told me, matter-of-factly. Willie died shortly afterward, but his son Big John now runs his farm in East Longmeadow. And Pepper Belle is still alive and well there.
Since we first met Migdol at that stable in Connecticut, Lou and I had come a long way in our understanding of Tourette’s syndrome in horses. We also had a deeper appreciation of the trials and tribulations of people living with Tourette’s syndrome. When we first observed Migdol’s strange behavior, however, we never dreamed for a moment that we could uncover a behavior best described as Equine Tourette’s Syndrome. Although we still need final confirmation of the genetics involved before we declare it equivalent to the human condition, we think we know what to look for.
There is a known link between Tourette’s and OCD, with about 60 percent of Touretters also having OCD. A small slice of DNA in the human genome, specifically a gene called SLITRK1, plays a role in the development of nerve cells and also expresses itself in areas of the brain relevant to Tourette’s syndrome. Disruption of this gene was found in a small percentage of Tourette’s syndrome sufferers. Along with SLITRK1, we believe that the same gene we saw at work in dogs and people with obsessive-compulsive disorder (CDH2) might also be involved in Tourette’s syndrome.
Dr. Shuster and I would certainly like to examine these genes in horses afflicted with Tourette’s. With that in mind, we may well call on Pepper Belle to step up one more time and provide a DNA sample—to help her own kind as well as shed more light on the origins of the human condition.