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Horses used in a therapy program for war veterans showed no evidence of stress arising from their involvement, an American study has shown.
Horses are increasingly being used in a range of therapeutic programs.
“It is important to understand the impact of such interventions on the stress level and quality of life for the horses involved,” Karyn Malinowski and her colleagues wrote in the Journal of Equine Veterinary Science.
Researchers conducted a pilot study to find out if taking part in equine-assisted activities and therapies would acutely alter physiological markers of stress and well-being in horses.
Nine healthy geldings, of various breeds, aged 10–23, were selected to take part in the study. All were conditioned and experienced as therapeutic riding horses.
The horses were monitored over five one-hour sessions of therapy involving veterans previously diagnosed with post-traumatic stress disorder (PTSD).
Of these horses, seven were selected at random to wear electrocardiogram units, and all nine were used for blood sampling to measure plasma cortisol and oxytocin levels.
Cortisol is a hormone related to stress. Oxytocin is sometimes known as “cuddle hormone” or the “love hormone” because it is released when people snuggle up or bond socially.
Each horse was randomly assigned to partner with a veteran for the sessions.
The veterans themselves were also assessed to determine the effects of the therapy work.
Stress levels in the horses, as demonstrated by plasma cortisol concentrations and heart-rate variability, did not change in the horses involved in the therapy sessions.
The lack of change in plasma oxytocin concentrations after sessions meant there was also no evidence of increased levels of happiness or well-being among the horses.
However, symptoms of PTSD did change significantly in the veterans who participated in this study.
Post-therapy measures of PTSD symptoms were significantly reduced except for interpersonal sensitivity and phobic anxiety. They experienced a significant decrease in anxiety and depression along with other symptoms of psychological distress and PTSD.
“To our knowledge, this is the first report of the measurement of oxytocin in horses used in equine-assisted activities and therapies programs,” the researchers said.
“Oxytocin has anti-stress effects by reducing glucocorticoid stress hormones in humans and animals and is associated with increases in parasympathetic function.
“We found no changes in plasma oxytocin concentrations in horses involved in [therapy] with veterans.
“This lack of change possibly could have been due to the time of blood sampling which occurred at 10 and 30 minutes post-therapy. Because the half-life of oxytocin is short, it may have cleared the bloodstream by the time our samples were taken.”
The scientists noted previous research showing that oxytocin concentrations in dogs and their owners increased after three minutes of interaction, where the owner stroked, petted, and talked to their dogs, and oxytocin concentrations almost doubled in both humans and dogs after positive interaction whereas cortisol concentrations decreased in humans only.
“Horses may not respond in the same manner as dogs after interaction with humans. Further research investigating the impact of horse–human interactions on oxytocin is warranted,” the study team wrote.
The study team comprised Karyn Malinowski, Chi Yee, Jenni Tevlin, Eric Birks, Mary Durando, Hossein Pournajafi-Nazarloo, Alan Cavaiola and Kenneth McKeever, variously affiliated with New Jersey’s Rutgers University, the State University of New Jersey, Sports Medicine and Imaging in Delaware, Indiana University, and Monmouth University, New Jersey.
The Effects of Equine Assisted Therapy on Plasma Cortisol and Oxytocin Concentrations and Heart Rate Variability in Horses and Measures of Symptoms of Post-Traumatic Stress Disorder in Veterans
Karyn Malinowski, Chi Yee, Jenni M. Tevlin, Eric K. Birks, Mary M. Durando, Hossein Pournajafi-Nazarloo, Alan A. Cavaiola, Kenneth H. McKeever