Unlike most wool fabric items, wool coats are not generally machine washable. This is due entirely to the materials used to provide the shape of the coats, which are not themselves machine washable. Doing so leads to a loss of shape for the coat.
The materials added to a wool coat that prevent washing provide the coat with strength and structure. They include the fabric linings of the coat along with padding material, which aid in stretch position. Many of these materials actually dissolve when machine washed. Though they cannot be machine washed, wool coats can be spot washed using home dry cleaning kits, or even pressed into shape at home.