Four horses rescued from a ranch in Lantry, South Dakota are now being cared for in Colorado.

Colorado Horse Rescue posted on Facebook the horses were part of a group of more than 800 that were impounded from the International Society for the Protection of Mustangs & Burros.

According to their post, that ranch is under criminal investigation for starvation and neglect.

The horses did receive care before being transferred to Colorado, but they still need some medical care and training.

"We've had our vet take a look at them and right now kind of their most urgent medical needs is de-worming," Rachel Corbman said, the operations manager at Colorado Horse Rescue. "We need to get them all trained. That's kind of the top priority. They are not even halter trained so we can't handle them to do much of anything."

Corbman tells 9NEWS the horses appear to be well-adjusted to people, which is good news.

"These guys - I've been really impressed with. They are all very quiet, very curious, very thoughtful," Corbman said. "You can work in and around them, and be kind of in their space and their pen, and they are not fearful or anything."

She went on to say, "They are really more inquisitive and just trying to figure out what we're all about - which is great because that really kind of sets them ahead from a training standpoint. That should make it quicker for a trainer to work with and at least get them to a good point."

Even then, she said it could still be three to six months before the horses are trained and ready to be adopted.