Lime in gateways and around troughs is recommended by all the sheep foot experts - if you have a problem with footrot or scald within a flock, that is. As ditw says, it kills the bugs so reduces spread of infection. I haven't used it myself and I don't know if it is as effective on other foot bugs as it is supposed to be on footrot and scald - but I can't see why it wouldn't be.
I don't know if it actually kills active infection in an individual sheep, as well as killing bugs on the ground which could otherwise infect other sheep.
I have used Cheviot Foot Paste, on veterinary advice, in a tup that kept getting 'angleberries' (granulomas.) It did help. I feel sure it would help with active footrot or scald too - but blue spray is so very effective I think we all just use that for those infections, eh? From moprabbit's description there wasn't any active footrot or scald, just flaky hoof coming away from the foot, which could mean an old footrot infection from which the sheep has now recovered, or Anke thought it sounded like Shelley hoof.