Fair warning. If you're a dog lover this one will make you mad, if not for its inhumanity but its ridiculousness. Taking down tanks is a difficult task and during WW2 the Soviet Russian Army thought that maybe man's best friend might be up to the task. Since 1924 the Soviet Union had been training dogs for rescue, first aid delivery, communications, tracking, and transport. But in the period between 1941 and 1942 the Soviet Army had its dog training schools shift their focus to training anti-tank dogs.
The idea was to use dogs as kamikaze, loading them with a payload of explosive that they would then run under a tank and detonate, destroying the tank (and killing the dog in the process).
But the dogs weren't so willing to go along with the idea. The noise of the tanks in battle often frightened them, making them easy targets or meaning they would run back to their own trenches, killing Soviet soldiers instead. The Soviets also made a serious error in training the dogs. The dogs were trained using Soviet tanks rather than German ones and because of their acute sense of smell this had the unforeseen consequence of having the dogs recognize the diesel engines of the Soviet tanks rather than the gasoline engines of the German tanks. Once deployed on the field the dogs would then seek out friendly tanks instead of the enemy.
There was an outcry against the use of anti-tank dogs with critics of the program saying that the army had grown so desperate it was willing to sacrifice animals. Starting in 1942 use of anti-tank dogs declined and military dogs were shifted to more suitable and humane tasks like sniffing out landmines and delivering supplies. Still, the training of anti-tank dogs continued until 1996.
(Image source: http://dogs-in-history.blogspot.com/2016/07/anti-tank-dogs-sent-on-suicide-missions.html)