Another natural remedy is MARMITE or VEGEMITE, do you have that in America? some cats like the taste others dont, but if its on their paws they will lick it off anyway, just do this every day, i have tried it, but i have not been consistent enough to know if it really works, i saw it on our television, it was recommended by a vet.
Its full of vitamins and so should do no harm to them at all, infact probably do them some good, and its quite cheap around 1.50 us for a jar, and last for ages.