Cerebral palsy (CP) is a neurological disease that occurs in 2–3/1,000 newborns [1] and causes movement and postural disorders due to non-progressive damage that occurs in the immature fetal or infant brain [2], leading to chronic neurological abnormalities and developmental disorders that require lifelong movement therapy [3]. An early diagnosis and various treatments, such as therapeutic exercise, braces, and surgical treatment, should be applied for comprehensive rehabilitation therapy [4].

Hippotherapy is a field of rehabilitation therapy to achieve physical, social, and psychological well-being through horse riding, which is a whole-body exercise. Subjects ride horses under the prescription of a professional faculty. Hippotherapy provides a new stimulus related to gait and helps balance and postural control in children with CP because the pelvic movements of a horse rider are similar to that of the pelvis during gait [5]. Hippotherapy is a good strategy to increase functioning in children with CP who need continued, varied, and repetitive treatment [6]. The physical effects and functional improvements after hippotherapy improve spatiotemporal parameters, such as gait speed, rhythm, width, and bilateral symmetry [7], as well as improve gross motor function and balance parameters [8].

However, hippotherapy lacks a scientific basis regarding psychosocial effects. McGibbon et al. [9] reported that hippotherapy applied twice weekly for 8 weeks in children with CP increases social activities, enables hobbies, and reduces energy expenditure during walking. Casady et al. [10] reported that hippotherapy once weekly for 10 weeks improves self-esteem and motivation for activities and that this fun increases participation by children with CP. However, their study was not based on objective results but on the study subject's opinion that they were very interested in participating in more hippotherapy and the author's view that hippotherapy motivates these children to actively participate in social activities [9,10]. Most caregivers of children with CP have psychological and emotional difficulties, such as inferiority and guilt, and experience limitations in time use and their home, conflicts with nondisabled children, and are isolated from neighbors [11].

Thus, in this study, we examined not only functional and balance improvements but also increases in motivation, confidence, concentration, and the sense of accomplishment in children with CP after hippotherapy. We also examined the psychological and emotional effects on the caregivers of the children participating in hippotherapy.

Previous studies on the effects of hippotherapy targeting children with CP mostly focused on trunk balance, gait, and balancing ability [23]. Shurtleff and Engsberg [24] reported that six patients showed improved neck and trunk balance after 12 weeks of hippotherapy, and Kwon et al. [8] reported that not only gross motor functions including gait but balance ability improved after 8 weeks of hippotherapy conducted twice weekly in a controlled clinical trial of 32 children with CP. In our study, PBS, which measures balance, improved by an average of 4 points, and the GMFM score increased by an average of 2.4 points, suggesting significant improvements after hippotherapy. This result was particularly dramatic in the dimension (E) of walking, running, and jumping. However, this was a pilot study without a comparison group and we only targeted a few patients, so the results are limited for demonstrating the effect of hippotherapy on improvements on the PBS and GMFM. However, Kwon et al. [8] showed a similar result in a controlled clinical trial in which the PBS increased 4.1 points, and the GMFM increased 1.7 points. Improvements in balance and gross motor function can be expected to some degree after once weekly hippotherapy for 10 weeks but additional study is required.

The improvements in physical ability caused by hippotherapy are related to the sensory inputs from the soft and rhythmical movements of the horse that are conveyed to the rider [12]. Static and kinetic movements, changes in center of gravity, and rotational movements all occur between the trunk and pelvis of a rider when the horse walks slowly, which is a new stimulus for children with CP who have not experienced normal gait [3]. Furthermore, the temperature of a horse is 1℃ higher than that of humans, allowing the rider to relax [25]. Patients were expected to maintain upright posture only using the reins without handles between sessions 6 and 10 when the horse's gait was increased, which contributed to improve balance. The children learned the horse's reactions during trotting by sitting and standing rapidly, which improved lower extremity muscle strength, perception of their body center, and balance ability.

We found no significant improvement on the K-MBI, which assesses activities of daily living. A previous study of 29 children with CP who were assessed using the WeeFIM after 10 weeks of hippotherapy showed no significant improvements [3]. In addition, no improvements on the K-MBI were observed in a study that applied hippotherapy targeting patients with a chronic brain disorder [26]. In contrast, activities of daily living improved after hippotherapy in patients with multiple sclerosis [27]. Improvement of independence in activities of daily living after hippotherapy may depend on age, diseases of the subjects, and hippotherapy duration.

Until now, only improvements in gait and balance ability were confirmed after hippotherapy in children with CP but a scientific basis for other psychosocial effects is lacking. Snider et al. [28] and Sterba [29] pointed out the absence of participation field results on the International Classification of Functioning, Disability, and Health (ICF) among study results on the effects of hippotherapy. Since then, one case about self-esteem and participation after hippotherapy was reported. A 6-year-old patient with mild ataxic CP and GMFCS level 1 showed improved self-esteem and participation measured by the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children, as well as functional gross motor function after 8 weeks of twice weekly therapy [30].

We expected that hippotherapy would improve emotional stability through interactions between the horse and children, the special experience in a natural environment, fun during therapy, and participation in a sports activity. However, we found no significant improvement on the psychological parameters. It may be that 10 weeks of once-weekly hippotherapy was insufficient compare to that in a prior study [30]. If we increased the frequency and duration of therapy, children would be expected to achieve physical improvements and fun activities.

Parents of children with CP are in the center of children's lives and therapies [31]. Most parents of disabled children show depressive symptoms [32] and this is consistently shown in studies targeting children with CP [33,34]. In our study, the BDI score of the caregivers was 16.50±11.97, which was consistent with a prior study [31]. Usually mothers of children with CP have high rates of depression and a low quality of life, so understanding the psychological and emotional state of mothers during rehabilitation therapy and improving their psychological and emotional status by improving quality of life and self-esteem of the patients provides psychological support. However, we found no psychological or emotional improvements in mothers of children with CP. Future study targeting more children with CP with more intensive hippotherapy is required.

This study had the following limitations. First, it only targeted children who underwent hippotherapy and did not compare children who did not participate in hippotherapy. Second, reliability was low because we only enrolled a few patients. Third, the same researcher who was not blinded conducted the functional evaluations before and after hippotherapy children, so we cannot exclude bias.

In conclusion, this was a pilot study that compared motor function and psychosocial parameters of children with CP before and after hippotherapy. Hippotherapy showed a positive effect on gross motor function and improved balance but we could not verify improvement in psychosocial parameters, such as depression, anxiety, and quality of life, in children and their caregivers as a result of the therapy.