Horse with thin coat after Ragwort Poisoning?

One of the wild ponies that live on Dartmoor came to our Animal Sanctuary in the Spring.

He had severe Ragwort poisoning and the vet said he should be euthanised.

We treated him with Milk Thistle over the following 4 months and he has pulled through and is doing well. He is lively frisky and happy, but he is clearly lonely for his herd.

The problem is that during the early stages of the ragwort poisoning most of his coat fell out, leaving huge sores all over his body. The sores have healed completely using a spray solution of Calendula tincture, but the coat still refuses to grow back properly in these areas, which cover about 40% of his body.

Unless we can find something that will encourage his coat to grow back to full thickness before the winter, he will not be able to be re-released back on to the moors to rejoin his herd as his coat will not be thick enough to endure the winter months.

If anyone has experience of ragwort poisoning and what might help his coat to regrow, I would be very grateful.

There is nothing in conventional veterinary therapy that can help, so I am looking for any alternative suggestions if possible.