Can we reduce pay for exempt employee who will miss work for intermittent FMLA leave?

Q. One of our salaried supervisors has informed us that he needs to take two hours off work each week for the next two months to undergo medical treatment. His physician has certified his illness as a “serious health condition” under the FMLA. May we reduce his pay for the time he will miss work, or are we required to continue to pay his full salary to retain his exempt status under the Fair Labor Standards Act?