The indigos and cribos harbor one of the most varied diets and voracious appetites in the reptile world, due much in part to their high metabolism and they are often likened to varanids without legs.
Drys will readily feed on most anything that will fit into their mouth and I recall speaking with an older gentleman in Homestead, FL who owned 10 acres, which backed up to a large bird sanctuary. He told me of an eastern indigo that would regularly eat leftover dry dog food from a bowl he set out in his yard. In the wild, they will feed on birds, rodents, fish, turtles, frogs, salamanders, other snakes (including venomous), a variety of road kill and, I suppose in at least one case, dry dog food.
In captivity, most will eat just about anything offered and I have a few that relish the occasional hot-dog!
Best regards,
Jeff

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Jeff Snodgres
University of Arkansas
snodgresjeffreys@uams.edu
501.603.1947