Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Aging is a normal physiological process that need not be accompanied by illness and suffering. This idea is pointed out by veterinarian Bernard S. Hershorn in his book, Active Years for Your Dog, written especially for the concerned owner of an aged, middle-aged, or even a young dog.
"Book Review: Active Years for Your Aging Dog,"
Iowa State University Veterinarian: Vol. 41
, Article 10.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol41/iss2/10