These are dogs that have undergone major mutations from being exposed to the F.E.V Usually, they are seen accompanying super mutants. They may have been created in the FEV lab of the Institute, along with most of the super mutants that are seen throughout the Wasteland.

Biology

Mutant hounds are usually several times bigger than normal stray dogs and mongrels. The modification imposed on their bodies by the F.E.V is similar to the one the super mutants went through: increase of muscle mass, depigmentation of the skin to a greenish color and complete loss of body hair. They are approximately 3 feet tall at the shoulder, and 5 feet long. Their intelligence seems to be affected too in the same way that a super mutant's is from the FEV. Super mutants seem to understand mutant hounds like no other in the Commonwealth. Their vocal cords have evolved to create a very deep and low howl that they use to alert their nearby brethren.