For many years, humans have benefited from horse-assisted therapy, reaping physical and psychological benefits. During hippotherapy, for example, a person with cerebral palsy or other neuromuscular disorders can benefit from trying to maintain balance in response to a horse's motion—riders tone, stretch, and strengthen the same muscle groups they would use in walking. Little scientific information, however, is available on how horse-assisted therapy impacts the horse.
"As equine-assisted therapy programs grow and grow, and we have more and more programs popping up throughout our country, I think it's incumbent on us as veterinarians to evaluate the impact of this type of activity on the horses, and to discover what are the short-term effects of this kind of work for horses and what are the long-term effects," said Dr. Marie Suthers-McCabe. She is an associate professor of human-companion animal interaction at the Virginia-Maryland Regional College of Veterinary Medicine.
To shed some light on the subject, Dr. Suthers-McCabe and Dr. Lynn Albano, a 2004 graduate of VMRCVM, launched a pilot study of 28 horses in four equine assisted-therapy programs. Five of the horses participated in two separate sessions, for a total of 33 samples. The horses involved 15 breeds, and each therapy program in the study focused on a different therapy discipline: equine-assisted mental health therapy, therapeutic horseback riding for children and for adults, and equine-facilitated psychotherapy.
The investigators took blood samples the morning prior to therapy sessions to determine baseline concentrations of cortisol. Additional blood samples were collected after therapy sessions for comparison. In addition, the researchers videotaped the horses before, during, and after their activities so that the veterinarians could look for behaviors thought to be indicators of stress, such as head weaving.
Dr. Suthers-McCabe, who gave a presentation at this year's AVMA Annual Convention, thought they would see a negative impact. "A therapy horse has to work hard," she said. If their riders have cerebral palsy, for example, they must really work to keep those riders in the saddle.
To their surprise, they discovered that cortisol concentrations decreased in 82 percent of the horses after a therapy session. Six of the horses had increased cortisol concentrations, but, in some of those cases, there were extenuating circumstances. One of the horses, for example, was new to the herd and had been involved in horse-to-horse contact. A second was seen on the videotape to be cribbing its stall doors, a sign of stress, before therapy sessions. And another was servicing an individual with extreme emotional problems.
In addition, the veterinarians found that cortisol concentrations actually decreased in some horses, which could indicate they were less stressed.
In the future, Dr. Suthers-McCabe hopes to launch a larger study. She also wants to compare concentrations of neurohormones such as oxytocin and prolactin in horses at rest carrying able-bodied riders with concentrations in horses performing therapeutic activities.
Such investigations may have important implications in identifying horses experiencing a level of stress that could lead to burnout and associated health and behavioral problems. They may also help identify which horses are not appropriate candidates to become therapy horses in the first place.
For more information on equine-assisted therapy, visit the American Hippotherapy Association at www.americanhippotherapyassociation.org or the North American Riding for the Handicapped Association at www.narha.org.