Dogs of war
Countries have tried to train dogs to run to the enemy with bombs strapped to their bodies for as long as there's been bombs, and war. Dogs can sniff out the presence of danger a human could never sense. Their legacy of service is as much responsible for the freedom we enjoy as any hand grenade.
No country has ever perfected this suicide weapon. The Germans desperately tried to employ bomb strapped dogs on the Eastern front during the latter part of the war as a means to stop the Russian T-34.
No animal, except for humans, will, as a force, attack another human while a devastating volume of fire pours over them. Explosions, fire, bullets, do not stop them. Their youth prevents them from realizing their lives are expandable, and often sacrificial. Even the steam coming from the ripped up bodies of their friends will slow them.
But after. Even though they might laugh and smile like all the other animals, the cage they come home in will always be too small.