One cuddled Dulux tightly, singing him a song. "I was born and bred on a farm. We had our own dog," he said.
Inmates spoken to said pet therapy was the highlight of their week.
Unlike able-bodied inmates, these men don't get to work the garden or any other physical activity.
So, patting animals provides welcome relief from Scrabble and reading.
"I see a trust in their eyes," one inmate said.
"They trust you not to hurt them - not to do anything wrong."
He remembered fondly the time a lama was brought in.
Having contact with animals was a lesson in empathy, he said.
"They help us do things that we wouldn't be doing before we saw them. An example of that is the way we communicate with people. We treat them the same way as we treat the animals, with courtesy and respect," the inmate said.
Another inmate would like to see the unit get its own cat, although he worried about its safety.