The dog and its owner were walking in an undeveloped area around the city of Richmond on New Year's Eve when two people riding four-wheel ATVs approached them.
The Fort Bend County Sheriff's Office says one of the suspects pulled out a silver gun and shot the dog. The second suspect then shot the animal one more time.
The dog's owner loaded his pet in his truck but the 4-year-old Labrador died on the way home.
Fort Bend County Crimes Stoppers is offering a reward of up to $5,000 for information leading to the arrest and conviction of the two suspects.