Ashleigh said: "I used to ride her. I never thrashed her or anything but I was always very careful about what I did. So the thought of people riding her, full-galloping down roads, it's just disgusting.
"She was a SPCA case from Waimarama and she had no trust in people when we first got her and she already had injuries.
"I couldn't ride her for two or more months, so those two months I just spent bonding with her. I'm just so thankful that she is alive because I was expecting the worst."
Mrs Steed said Stella was never going to be a show pony because of her injuries and would come up lame if ridden too hard: "The damage that was done to her is exactly what we were trying to avoid.
"Because of the impact that they were putting her through, [it] has caused the bone to start pushing through the hoof," she said. "There's not a lot of hoof left to really put shoes on."
Ashleigh said Facebook was used to appeal for any sightings of her pet and she was bombarded with photos and screenshots of possible leads.
"As a human being, you should be able to see and understand that this horse was in pain," Ashleigh said. "How could you not see?"
Mrs Steed said she had contacted police but was unsure what action they were taking, as she had not heard from them since Monday.
A police representative yesterday confirmed the case was being investigated.
Those wishing to donate to help cover Stella's vet bills can do so by going online to givealittle.co.nz/cause/helpstella