hind leg vs hind limb

hind leg

noun
  • Either of the two legs towards the rear of a four-legged animal. 

hind limb

noun
  • A posterior limb on an animal. When referring to quadrupeds, the term hind leg is often instead used. 

How often have the words hind leg and hind limb occurred in a corpus of books? (source: Google Ngram Viewer )