History
The so called "Killer Beasts" were scientific abominations created by the Nazis during World War II. They were attack dogs specially bred and biologically engineered to have poison glands in their mouths, making their bites lethal. Their creation was commissioned by Oberst von Steibel to be used in the first phase of an invasion of the United States. A number of these dogs were smuggled into the US and used in an attack on Camp Lehigh that saw the death of several soldiers during tank maneuver practice.
One of these dogs was killed by Captain America who tossed his shield at the creature while protecting his young sidekick Bucky from attack. The rest of the dogs were slain when Captain America blew up the truck transporting them with a Nazi grenade.[1]
If anymore of these dogs existed or were used again is unrecorded. If such was the case, they were likely destroyed before the war's end.