I can't name the drug, our vet used it yesterday.

Draxxin, Zactran, Excede, NuFlor? Lotsa stuff will work on interdigital pododermatitis (fancy word for foot rot)

Old school remedy, but it works.....

Put the cow up in a dry lot and for 5-7 days, pour kerosene on the foot.

To prevent foot rot, add iodine to your feed. When I had cows, I mixed about 4-6 oz. of iodine powder with 50 lbs of salt. The blocks of salt with iodine, dont have enough in them to prevent the rot. Once I started doing this, I never had another cow with foot rot.