on the hoof

from The Collaborative International Dictionary of English v.0.48

Hoof \Hoof\, v. i.
   1. To walk as cattle. [R.] --William Scott.
      [1913 Webster]

   2. To be on a tramp; to foot. [Slang, U.S.]
      [1913 Webster]

   {To hoof it}, to foot it.

   {On the hoof}, of cattle, standing (on the hoof); not
      slaughtered.

   {beef on the hoof}, live cattle.
      [Webster 1913 Suppl.]