He "understands to a certain degree" that his horse is gone.
"He's not crying about it but with Tyler it's constantly on his mind. I can occasionally distract him but the conversation will always come back to his horse.
"Every day he comes home from school and asks 'have we found Halo?'
"She's a companion."
Research shows equine therapy is effective for treating adolescents experiencing depression, anxiety, trauma-related symptoms, ADHD, autism, and other mental health conditions.
Spending time with horses reduces the stress hormone cortisol, and lowers blood pressure.
Bay of Islands Riding for the Disabled volunteer Glenys Rossell said horses help improve children's self-esteem, confidence, communication and trust.
"A lot of autistic kids have an empathy with the horses and the horses will respond to them and drop down to their level."
Mokaraka said he has reported Halo's disappearance to police, but "what's more important to us is that we get her back. We're not going to press charges."
Anyone with information is urged to call Mokaraka on 021 631641.