Check for Lice
Lice can be serious skin parasites. If a goat scratches, it probably has lice. Some goats are more susceptible to lice than others. Often the single emaciated kid in a pen has a huge load of body lice.
Use a dairy insecticide powder to help keep lice under control. It is worthwhile clipping goats completely in warm weather. This will also help to get rid of lice.