You should have a supply of DOT exam forms and the medical certificate on hand at all times.  Often, motor carriers will have the drivers bring in their own modified forms.  You can download them all right here:

Here are the most common forms you’ll need for DOT exams:

– See more at: http://www.fmcsa.dot.gov/mission/forms#sthash.9Cv6EAHk.dpuf