His owners' other two dogs didn't eat the meatballs tossed in the yard.
Oreo's owner, Jeannene Smith, says her dogs bark, but can't think why anyone would want to kill them.
"We've asked neighbors, are they bothering you, and they say no, they bark but they're doing their job," she said.
Friends are helping the owners cover Oreo's $10,000 vet bill.
Police are investigating and say five other dogs have been poisoned in the neighborhood in recent years.