castrate vs spay

castrate

verb
  • To remove the ovaries and/or uterus of an animal. 

  • To take something from; to render imperfect or ineffectual. 

  • To remove the testicles of a person or animal. 

noun
  • A castrated man; a eunuch. 

spay

verb
  • To remove or destroy the ovaries and/or uterus (of a female animal) so that she cannot become pregnant. 

noun
  • The act of spaying an animal. 

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