Perhaps if we get a warm day you could give her a really good wash - I'm not sure about hibiscrub but you could ask your vet or local horse shop if there's a medicated shampoo that might help. Regular grooming with soft clean brushes too should help bring out the dandruff.
My usually beautiful, gleaming DM looks like a cruelty case at the moment.
She has been developing bald patches & dry, flaky skin at an alarming rate. I had to call the vet out on Tuesday to a nasty cut & she diagnosed the hair loss to rain scald. She gave her an anti mite injection as a precaution (though no evidence of lice etc) & she is on antibiotics for the cut which will help any skin infection...but anything else I can do??
The vet just said once her summer coat comes through she will look like a different pony & it no way affects her welfare..but she looks AWFUL!!!