Good morning. I am Dr. Loretta.
The treatment for Mud fever or Equine Pastern Dermatitis is as follows: Removing Sara for the area that is damp and keeping her in a very dry area. Then cleaning with a chlorhexidine scrub so that every scab is removed and the hair clipped away. Dry this area thoroughly and then apply a Creme containing Zinc as an anti inflammatory medication. If this is done daily, it will help. Check this LINK :
This will give you more tips to help Sara past this difficult disease.