And Ms Sellers said that was the case for some of the riders.
"We have some riders who are just coming to watch because they are too scared to hop on a horse that isn't the one they usually ride."
The incident on Friday night involved a group of teens that jumped the fence on the corner of Purnell and London Street to enter the paddock of ten horses and cause havoc.
A video, taken by one of the offenders, recorded the horses being kicked and chased and tails being pulled.
The horses were used in an educational and therapeutic programme for people with disabilities, and had to be carefully trained before it was safe for them to ridden by the clients.
She said it was hard to say how long the horses would need to recover or even if they could be ridden again.
"We have two in the recovery paddock, one that was run over by another horse who had her tail pulled, and one that has a bad back. Then we have another one who had her tail swung on who is in the main stables doing a lot of lying down and sleeping."
Ms Sellars said another three horses had been to taken to another paddock for a break.
"One of our horses we can't even touch his back on because he's so scared, and he had only started to be ridden a week ago."
"All the horses have been doing a lot of sleep and it's fair to say that both the riders and horses are traumatised."
Facebook users have provided names for some of the people in the video, which have been passed on to police.
Police are investigating the matter.
