During the '50s & '60s, veterinarians throughout the U.S. had more clients seeking their services than the profession could comfortably manage. The '70's brought about a trend of decreasing client visits that particularly influenced most small animal practitioners.
Lewis, Robert E.
"Profiles of Clients: The Morris Foundation Study,"
Iowa State University Veterinarian: Vol. 43
, Article 6.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol43/iss1/6