There was a study conducted and published in the Journal of the American Academy of Child & Adolescent Psychiatry that looked at the benefits of Therapeutic Horseback Riding on children and adolescents with autism spectrum disorder.

The study found that there was significant post-intervention improvements on those that were in the therapeutic horseback riding group (compared to the control group). It showed that therapeutic riding can effect positive changes in irritability, hyperactivity, social and communication behaviors in children and adolescents with ASD. There were improvements in social cognition and communication, along with significant improvements in the amount of words and different words spoken.

You can read the whole article here.