BOULDER, Colo. -- Police in Superior are trying to determine who left poison-laced hamburger patties on the lawn at a condo complex, according to the Boulder Daily Camera newspaper .

The newspaper is reporting that two puppies ate the meat.

One of the puppy owners discovered the burgers had been stuffed with bluish-green tablets when she went to throw them away.

Veterinarians told the puppy owners the hamburgers contained d-Con.

The puppies were given injections to induce vomiting, but they must keep taking medication for a month.

Read more about the case in the Boulder Daily Camera newspaper.