mud puppy vs waterdog

mud puppy

waterdog

noun
  • The mature larva of an ambystomid salamander, particularly that of the tiger salamander (Ambystoma tigrinum). 

  • An axolotl (Ambystoma mexicanum). 

  • A small irregular floating cloud supposed to indicate rain. 

  • A mudpuppy. 

How often have the words mud puppy and waterdog occurred in a corpus of books? (source: Google Ngram Viewer )