I had a call from a client today with a great question - her horse had lots of little crusty bumps around his pasterns, and her farrier had told her it was probably "scratches". She called for more information about this condition, and what to do about it. "Scratches" is also called "mud fever", "dew poisoning", or more medically appropriate "pastern dermatitis". "Derm" means skin, and "itis" means inflammation, so "dermatitis" just translates to "inflammation of the skin" which, in pastern dermatitis, occurs at the pastern. The term is descriptive, but it doesn't tell us anything about what causes it.