Evidence to support the use of equine-related treatments for individuals with mental disorders is scant, a review published in a peer-reviewed journal has found.
The researchers from the University of Southern Mississippi and Emory University said equine-related treatments for mental disorders were becoming increasingly popular for a variety of diagnoses, despite limited investigation.
They concluded there was negligible evidence that horse therapies offered benefits to individuals with mental disorders or other psychological difficulties.
Michael Anestis, a professor of psychology at the University of Southern Mississippi, and his colleagues set about examining the quality and findings of peer-reviewed research into such treatments.
They examined 14 studies found in databases and article reference sections, finding that all of them were compromised by what they described as a substantial number of threats to validity.
This, they said, called into question the meaning and clinical significance of their findings.
They found that the studies – 10 of which used children and four used adults – failed to provide consistent evidence that equine-related treatments, which include equine-assisted psychotherapy and therapeutic horseback riding, were superior to the mere passage of time in the treatment of any mental disorder.
“The current evidence base does not justify the marketing and utilization of equine-related treatments for mental disorders,” they concluded in their review, published in the Journal of Clinical Psychology.
“Such services should not be offered to the public unless and until well-designed studies provide evidence that justify different conclusions,” they said.
The researchers said treatments must earn their position in the marketplace through a stepwise process whereby multiple independent research teams establish that the intervention yields consistent and clinically meaningful and cost-effective improvements.
Horse-based therapies had been subjected only to minimal empirical investigation
The horse, they said, was theorized to provide feedback on subtle mood changes, with some authors suggesting that the animal served as a “large biofeedback machine”.
Such therapies had even been promoted on celebrity mental health programs, such as Dr Phil and The Dr Oz Show. Some practitioners had built upon such coverage to make sweeping claims about their effectiveness, they said.
Anestis and his colleagues identified a range of issues across the studies which threatened the validity of the findings. These ranged from a lack of precision in measuring the results to flaws in the design of the study which made the results difficult to interpret.
They identified three violations which they said occurred in most of the studies.
“These violations are the result of an almost uniform lack of appropriate experimental controls, proper experimental procedures necessary to test treatment outcome, and independent, unbiased raters,” the research team said.
“Any one of these violations would typically disqualify studies in the psychotherapy outcome literature from serious scholarly consideration.”
The studies, they said, tended not to allow for the novelty effect – the elation and energy arising from a new and exciting experience.
“Equine approaches are especially vulnerable to novelty effects because interacting with a horse is probably an unusual and exciting experience for most individuals.”
The studies also tended to fall victim to what they called experimenter expectancies, noting: “Experimenters can convey their expectations about desirable responses to the participant, thereby influencing participant response.”
They also took issue with a lack of formal therapy structure in many of the studies.
“Although some of the studies mentioned following guidelines and manuals, none of the 14 studies reported having any evaluation of treatment fidelity in place.
“This combination of lack of therapy structure and lack of a system of checks to determine the faithful implementation of the treatment raises significant questions about the independent variable under study,” they wrote.
The researchers continued: “When considered in aggregate, findings from studies on equine-related treatment provide inconsistent and less than compelling support for its efficacy in the treatment of any mental disorder.
“Studies that lack control groups often yielded improvement from pre- to post-treatment; however, such findings cannot demonstrate an effect of treatment.
Studies with control groups neglected to use random assignment and several studies of research that used control groups were unable to show favorable results for equine-related treatments.
“… The results fall well short of the standards set forth for establishing empirical support for treatments.”
The researchers said the development of new, more effective treatments for mental disorders was a noble goal, as was the desire to provide promising treatments to those in need.
However, there were difficulties when the dissemination of a treatment extended beyond the evidence that supported it.
They continued: “The results [of the review] allow us to provide an unequivocal summary statement: The empirical literature on equine-related treatments for mental illness is limited in scope, the studies that exist are compromised by multiple methodological flaws, and there is no consistent evidence that the treatments afford benefits beyond those offered by the passage of time.
“Given the time and expense associated with equine-related treatments (and the dissemination of any new treatment), there appears to be scant justification at present for its use as a standalone or adjunctive treatment for any mental disorder.”
They said it was possible that, in coming years, randomized controlled trials with assessments conducted by independent observers might provide compelling evidence for the use of equine-related treatments for specific mental disorders.
“Such rigorous scientific standards are not yet close to being satisfied,” they said.
“Therefore, we have serious scientific and ethical concerns regarding the continued use and marketing of equine-assisted psychotherapy and therapeutic horseback riding for mental illness or psychological maladjustment more broadly.”
The research team raised questions around the issue of informed consent, which involves explaining to clients the evidence for and against available treatments.
Under the American Psychological Association’s guidelines for therapeutic situations for which generally recognized techniques and procedures had not been established, psychologists should tell clients of the developing nature of the treatment, the potential risks involved, alternative options, and the voluntary nature of their participation.
Given the lack of evidence for horse-related therapies and their continued promotion, it seemed unlikely full informed consent was routinely obtained, they suggested.
“We urge all practitioners of equine-related treatments to inform their clients of the extremely limited evidence base for their intervention, as well as to educate them regarding alternative and better supported treatment options.
“Belief in the healing potential of a specific treatment is understandable; however, in the absence of rigorous evidence, such beliefs can sometimes be dangerous for consumers, most of whom lack the scientific training to evaluate assertions regarding the treatment’s efficacy and effectiveness.”
They continued: “Consumers who come to believe in the effectiveness of an unsupported treatment run the risk of being directed away from effective care and towards an experimental approach less likely to yield beneficial results.
“Given the strong evidence base for many treatments for a wide variety of diagnoses … we recommend that, in view of the current evidence base, individuals in need of mental health services avoid seeking out equine-related treatments, and treatment centers avoid practicing this approach.”
Anestis was joined in conducting the review by Joye Anestis, Laci Zawilinski and Tiffany Hopkins, from the University of Southern Mississippi; and Scott Lillenfeld, from Emory University.
Anestis, M. D., Anestis, J. C., Zawilinski, L. L., Hopkins, T. A. and Lilienfeld, S. O. (2014), Equine-Related Treatments For Mental Disorders Lack Empirical Support: A Systematic Review of Empirical Investigations. J. Clin. Psychol., 70: 1115–1132. doi: 10.1002/jclp.22113
The abstract can be read here.