Why rats can't vomit, and why humans do
ratbehavior.org
ratbehavior.org
It's fascinating.
While I don't own a dog, from what I've read of Dave Barry, dogs excel at locating and responding to all unknown emetics, too.
"A broad, comprehensive survey of many different species is needed before the evolution of vomiting is fully understood."
_Needed_.
(Interesting read though)
Before you get disgusted: some humans will chew food in the month to feed to a baby. And pigeons can't chew.