"A few years go by, and at one of the visits the bank trustees noticed that the cats were looking quite frisky," Walsh says. "So they did some checking. It seems that the butler was replacing some of the cats that died to keep the trust going."
To guard against future replacements, the trustees had the remaining original cats tattooed. "It was done in a humane way," Walsh says.
Observers say they see the trend of people providing for their pets in estate plans to only increase.
Lynnette Hart, a professor of behavior and human-animal interaction at the School of Veterinary Medicine at the University of California at Davis, says that for some people, pets are no different from other members of the family.
"People are living in smaller families and more people are living alone," she says. "We have more space available to build relationships with the animals that we have."