apathy vs colt's tooth

apathy

noun
  • Lack of emotion or motivation; lack of interest or enthusiasm towards something; disinterest (in something). 

colt's tooth

noun
  • One of a horse's first set of teeth. 

  • Youthful desires, especially lust. 

How often have the words apathy and colt's tooth occurred in a corpus of books? (source: Google Ngram Viewer )