Lucky the explosives detection dog working in Afghanistan has been declared missing in action, and is probably dead.
The golden Labrador broke away from his handlers in the Australian Special Forces and Afghan National Police force during a fight on July 4.
Sergeant Todd Langley died during the same incident in the northern Helmand province.
The commanding officer of the special operations task group, Lieutenant Colonel G, said small arms and rocket-propelled grenade fire during the skirmish prevented soldiers from safely retrieving Lucky at the time.
He said they made repeated attempts to call the dog back but the animal was last seen near a concentrated group of insurgents.
Post-action analysis of the battle and subsequent monitoring of the region led Defence to conclude that Lucky was likely killed in the fighting.
"Our dogs are important to our operations and our handlers form extremely close bonds with their dog," Lieutenant Colonel G said.
Losing a dog was is particularly hard on handlers but it also affected the whole team who enjoy their company.
Defence delayed announcing Lucky's disappearance and likely death until it had exhausted all avenues of searching for him, including offering a reward in the local area.