From Command and Conquer Wiki

During the Great World War II, in order to guard their complexes from spies, the Soviets trained and kept attack dogs. In order to sustain their population, specialized structures called kennels were constructed. The kennel was the place where, when not on duty, dogs could rest and eat before their next assignment as well as where Soviet trainers could train their dogs.

With attack dogs no longer regular military units, the kennels were withdrawn from use.