medical doctor vs veterinary

medical doctor

noun
  • A physician; a person who holds a doctoral degree or first professional degree in medicine, and practices in that profession. 

veterinary

noun
  • A veterinary surgeon; a veterinarian. 

adj
  • Of or relating to the medical or surgical treatment of animals, especially domestic and farm animals. 

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