The etymology of "vetting" a person or a fact

A reader of this blog used the term "vetting" -

"a process of examination and evaluation, generally referring to performing a background check on someone before offering him or her employment, conferring an award, etc. In addition, in intelligence gathering, assets are vetted to determine their usefulness"

- in a comment, and I wondered where the term comes from.  Here's the answer:

To vet was originally a horse-racing term, referring to the requirement that a horse be checked for health and soundness by a veterinarian before being allowed to race. Thus, it has taken the general meaning "to check."  It is a figurative contraction of veterinarian, which originated in the mid-17th century... By the early 1900s, vet had begun to be used as a synonym for evaluate, especially in the context of searching for flaws.