FLORENCE, Ariz. — When a suicide bomber entered an American military barracks in Afghanistan in February, it was not American soldiers but Afghan stray dogs that confronted him. Target and two other dogs snarled, barked and snapped at the man, who detonated his bomb at the entrance to the facility but did not kill anyone.

The dogs were from the Dand Aw Patan district, in the eastern Paktia Province near the Pakistani border. One died of wounds suffered in the blast, and months later, Target and the other dog, Rufus, were flown to the United States by a charity and adopted by families. Target — who received a hero’s welcome, including an appearance on “The Oprah Winfrey Show” — went to live with the family of Sgt. Terry Young, 37, an Army medic who witnessed the animals’ bravery that night and helped treat the dogs and several American soldiers who were wounded.

The glory, though, was short-lived. Target, after learning to get along with the Young family’s other dog in Arizona, becoming accustomed to dog food and to using a doggie door to relieve herself, escaped from her yard. She was captured last week and euthanized by mistake.

“My 4-year-old keeps saying: ‘Daddy, bring Target home. Daddy, get the poison out,’ ” Sergeant Young, a father of three, said in a telephone interview, his voice choking with emotion. “Obviously, at first there was extreme anger and horror. Now that a couple of days have passed, the anger has been replaced by sorrow.”