An unidentified employee at the Pinal County facility was placed on administrative leave after euthanizing the female shepherd mix by mistake, county Animal Care and Control officials said Monday.
"When it comes to euthanizing an animal, there are some clear-cut procedures to follow," Ruth Stalter, the county animal control director, said in a statement. "Based on my preliminary investigation, our employee did not follow those procedures."
Sgt. Terry Young, the owner of the dog, told The Arizona Republic, "I just can't believe that something like this would happen to such a good dog."
Target frightened a suicide bomber inside a military base and potentially saved dozens of soldiers' lives, Young said.
He said the dog was treated like royalty from then on at the base at Dand Patan, near the Pakistan border.
Young brought Target to the San Tan Valley area southeast of Phoenix in August, when he returned home from his tour of duty.
The dog escaped from the family's back yard Friday. Young put out online notices and contacted TV stations that did reports on the missing hero dog.
A neighbor found Target wandering later Friday, put her in his back yard and called the pound. The dog did not have a microchip or tag.