ST. LOUIS • For at least the second time in two months, police are investigating how a dog was so badly burned that caregivers decided he needed to be euthanized.

Zeus, a three-year-old pitbull, was found between 1 and 2 p.m. Tuesday in the 5700 block of Amelia Avenue with third-degree burns over 75 percent of his head, officials said. The dog also had burns on one of his paws and across the left side of his body.

"This was an intentional act," Mike Perkins, director of the Humane Society of Missouri's animal cruelty task force, said of Zeus' injuries. "It's an unforgivable crime what someone did to this animal."

Workers with the Humane Society of Missouri euthanized Zeus on Tuesday afternoon because of the severity of his injuries, Perkins said. The dog appeared to have been well-fed and healthy before suffering the burns.

Zeus' owner told police the dog disappeared about 7 p.m. Monday. The next day, a neighbor called the owner to report seeing Zeus in a neighbor's back yard, suffering from burns.

The owner turned Zeus over to the humane society, which is offering a $2,500 reward for information leading to the arrest and conviction of Zeus' abuser or abusers.

Last month, a three-year-old terrier-shepherd mix named Brownie died of organ failure as a result of being burned. Brownie was found badly burned July 10 in the 4300 block of Cote Brilliante Avenue.

A woman was charged in that case. Adrienne Martin, 35, the sister-in-law of the dog's owner, admitted to police to burning Brownie, saying the dog had bitten her son the day before.

Anyone with information about the latest dog burning case is asked to call the humane society's animal cruelty hotline at 314-647-4400.