Researchers find equine self-mutilation syndrome is equine equivalent of Tourette syndrome

EXTREMELY RARE and once thought confined to Arabian stallions, equine self-mutilation syndrome, or ESMS, has been evidenced in Thoroughbreds, Quarter Horses, Standardbreds, Paints, and Oldenburgs of both sexes and is considered to be the equine equivalent of Tourette syndrome, a human disorder frequently accompanied by obsessive and compulsive disorder.

"It's about as close as you can get to Tourette for an animal model," said Nicholas H. Dodman, B.V.M.S., of Tufts University School of Veterinary Medicine, who has had three studies published about equine self-mutilation syndrome, in 1988, '94, and 2004.

Mark Levine, the vice president for development of the Tourette Syndrome Association in Bayside, New York, agreed. "You can't say it's Tourette's, but it's the equine model of Tourette," Levine said.

The Tourette Syndrome Association funded Dodman's $25,000 study in 2004 of pharmacological treatment of equine self-mutilation syndrome with his longtime friend and colleague, Louis Shuster, Ph.D., a professor in the Tufts University School of Medicine.

"This is something Dr. Dodman has devoted a good amount of his life to," Levine said. "We funded the study because you never know what you're going to find. We felt there was something to gain."

They were right. One of the eight horses identified as flank-biters who participated in Dodman's 2004 study was a Standardbred mare named Pepper Belle, who won five of 15 races despite equine self-mutilation syndrome and has subsequently appeared at several schools with Dodman, Levine, and her owner and trainer, Willie J. Ferrero, and his son, John, to promote better understanding of Tourette syndrome.

"One of the nice things that came from the study was Pepper Belle," Levine said, "and Pepper Belle and the Ferreros are spreading awareness of Tourette's syndrome throughout New England." And elsewhere, thanks to Willie J. Ferrero's book, Pepper Belle, a fictionalized account of the now-13-year-old mare's life.

Global search

But there was very little literature or even data about equine self-mutilation syndrome before 1990. If there had been, Jo Anne Normile, who subsequently founded the Thoroughbred rescue organization CANTER, might have had some sense of what was wrong with her yearling Quarter Horse gelding when he began acting strangely on her farm in Plymouth, Michigan, in 1990.

"He'd grab his side [flank] with his teeth like a dog would grab a rag, shake it, fall down, and get up and do it again," said Normile. He would also pin his ears back and strike out with his back legs. After veterinarians ruled out the cause of the behavior was colic, Normile tried every thing she could.

"I checked for flies, parasites, a rash, but I found nothing," Normile said. "We had a parade of veterinarians. No one knew what was going on." The gelding's suffering weighed heavily on Normile, who decided to euthanize him on June 21, 1990. She did not forget his pain. "After he was put down, I had this feeling I had to do something," Normile said. "I had to make his life worthwhile. I became driven with the thought that his life made a difference. I needed to make his life have a deeper meaning."

Normile sent videotapes of the gelding to veterinarians around the world. A name she kept hearing from the veterinarians who responded was Dodman, who had established a reputation for dealing with cribbing, stall walking, and weaving in horses. A native of London, Dodman came to the United States in 1981. In 1984, he and Shuster were invited by a woman who owned an Arabian stallion in Connecticut to observe the horse's erratic behavior, which included spinning around and making unnatural noises.

Dodman, now 59, and Shuster, now 71, decided to investigate. "The two of us teamed up, an odd couple really," Dodman said. "He researches human medicine, and I was a veterinary anesthesiologist. We called ourselves 'The Crib Busters.'"

When they reached the woman's farm, they observed her horse's strange behavior. "He was running around, and, suddenly, he would stop, spin in a tight circle, and make a peculiar noise, wrrrrummmppphhh," Dodman said. "It was a strange noise. Then he would kick out with his back leg. I'd never seen anything like it."

Back at Tufts, Dodman discovered that self-abusive behavior in horses had been written about in a 1992 book by Katherine Houpt, V.M.D., Ph.D., titled Domestic Animal Behavior for Veterinarians and Animal Scientists. "She said it was very rare and thought to affect Arabian stallions only," Dodman said. "Our horse was an Arabian stallion. It looked like she was right. It was right after that that I got a call from Jo Anne Normile."

Dodman was immediately intrigued. Normile's horse was a different breed and was a gelding, not a stallion. "She sent me a videotape [of Dan The Man]," Dodman said. "I saw this sad scene of a pathetic horse who looked like he'd been stung by bees. He would spin in circles. He got thinner and thinner and kept getting more obsessed with the spinning. She made it her life's mission to get to the bottom of this. I realized I had tapped into this woman's amazing energy."

After sending Dodman a sample of her gelding's post-mortal tissue, Normile visited Dodman at Tufts. They decided to do a study and eventually advertised in 19 equine magazines with a combined circulation of more than 450,000 that they wanted to contact owners whose horses had demonstrated flank-biting or similar behavior that could be described as self-mutilation. Questionnaires were mailed to all owners who responded.

Fifty-two owners of 59 horses returned questionnaires documenting their horses' behavior. Two horses were omitted from the study because they had an organic cause for their behavior. Of the remaining 57 horses, 31 were geldings, 20 were stallions, and six were mares. Of the 57, there were 14 Arabians, nine Quarter Horses, eight Standardbreds, six of mixed breeding, and representatives of 11 other breeds.

Juvenile onset

The study showed that equine self-mutilation syndrome was most likely to arise in the first two years of a horse's life, with a median age of 18.5 months. Most horses exhibited their behavior on a daily basis, and some had numerous episodes daily. The episodes lasted from seconds to hours with the median being 70 seconds. The study concluded that episodes of self-mutilation "frequently were precipitated by environmental stresses, including anticipation of eating, interaction with other horses, particularly of the opposite sex, and inactivity."

Dodman's study of equine self-mutilation syndrome, which was published in the April 15, 1994, edition of the Journal of the American Veterinary Medical Association, noted several parallels between equine self-mutilation syndrome and Tourette syndrome and obsessive compulsive disorder in humans, stating "there is no doubt to the compulsive nature" of equine self-mutilation syndrome.

A 1988 study by Dodman on equine self-mutilation syndrome dealt specifically with the effectiveness of one narcotic antagonist (nalmefene) to suppress self-mutilation behavior in a single stallion.

A more compelling connection between Tourette syndrome and equine self-mutilation syndrome would be made after Dodman and Shuster's 1994 study that was funded by the Tourette Syndrome Association and published ten years later in the International Journal of Applied Research in Veterinary Medicine. "The people at the Tourette association were relieved to see it in another species," Dodman said.

This time, eight horses identified as flank-biters were admitted to the Large Animal Hospital of the Tufts University School of Veterinary Medicine. Three were Arabian stallions, one was a Thoroughbred mare, one a Standardbred mare (Pepper Belle), one a Quarter Horse gelding, one a Paint stallion, and one an Oldenburg gelding. Both the Thoroughbred and the Standardbred mare were two years old. The other six ranged in age from three to 15.

Future work

The horses were observed in a padded stall equipped with a wall-mounted video camera wired to a television and video camera recorder. The horses were there for four to five weeks and treated with various medications to determine any similarities between equine self-mutilation syndrome and Tourette syndrome.

"It looked like a Corvette; let's pop up the hood and look at the cylinders," Dodman said. "We gave them similar drugs used to treat Tourette."

Dodman concluded that equine self-mutilation syndrome mirrors Tourette, including its genetic origin. "It's about as close as you can get to Tourette for an animal model," Dodman said. "Horses have a predisposition to sniffing, which humans have, and with touching the borders of their periphery, a preoccupation with thresholds, and make a strange noise not normally heard. Not all of them do it, but not all humans do it."

Indeed, Levine said only 10% of people with Tourette utter out-of-context profanities. "When you first mention Tourette syndrome, people think it's cursing," Levine said. "People call it the cursing disease. But it affects only 10% of people with full-blown Tourette. And it's not a disease. It's a neurobiological disorder."

Apparently, equine self-mutilation syndrome is also neurobiological in origin, though more research obviously is needed on a topic that seldom has been addressed in the equine industry.

In the interim, Willie and John Ferrero have taken Pepper Belle to schools around New England to educate children--and occasionally their teachers and administrators--about Tourette syndrome. "They show tapes of Pepper Belle's tics first and then tapes of her races," Levine said. "And the beautiful thing is that kids love horses. They will remember Pepper Belle as a winner and figure out that you can overcome the disorder. As Willie likes to say, 'You can be a champion despite Tourette syndrome.'"

By sending that message, Pepper Belle has validated Normile's fervent wish that her own horse's life served a greater purpose. "I loved him so much," Normile said. "He was so beautiful, too. He was put on this earth for a reason, and it wasn't just to suffer with that disease."