SIERRA VISTA — Nine-year-old Joshua Harrington loves Tuesdays. From the time he started kindergarten, this fourth-grader has been visiting CANTER (Cochise Area Network of Therapeutic Equestrian Resources) every Tuesday where he’s enrolled in a therapeutic riding program. Harrington, who is autistic, is one of about 90 individuals that benefit from the program. The moment he settles onto the back of a horse, his entire demeanor changes. While riding around the arena on a horse named Hickory, Harrington goes from distracted to focused. “He’s on the lower end of the (autistic) spectrum, so his communication and social skills are affected,” said...