Anti-tank dogs were dogs with explosives placed on their backs. These dogs were trained to run under enemy tanks. The explosives were then remotely detonated in order to destroy the target tank.
These dogs were trained by the Soviet Union during World War II to be used against German armored vehicles. They were trained on Russian tanks, which used diesel fuel. In battle, the dogs often ran toward the smell of diesel fuel from the Soviet tanks instead of the intended German targets.
The German Army soon learned about the dogs, so all Russian dogs were shot on sight by the Germans. Very few dogs remained in the Eastern Front as a result of this.
After the war better weapons against tanks were made. Therefore, it is unlikely that anti-tank dogs will ever be used again.