Did they look like bred lab cats?
From the ASPCA web site:
“Each year, approximately 2.7 million animals are euthanized (1.2 million dogs and 1.4 million cats).”
“Of the cats entering shelters, approximately 37% are adopted, 41% are euthanized, and less than 5% of cats who came in as strays are returned to their owners.”
Some of those make their way to anatomy labs.