They need to be checked regularly, to be trimmed and to ensure they don't have any infections like foot rot (nice). So we round them all up (which is another story - the next time we try to herd 15 sheep from a large field into a small pen using a sunny afternoon, five family members, a teenage lurcher, a sausage dog, one long rope and a lot of swearing we'll invite a paying audience), check them all, treat any that need it and let them all back out into the field, grumpier but lighter of foot! The marks you see on their faces is safe spray so we know which ones we've checked.
ps: sheep's feet or sheep feet? hmm... answers on a postcard please.