Dogs still exist in the World After the Fall. They are varied between the old breeds, some new, and even some breeds mutated because of Ruin.
One of those different breeds — perhaps mutated — is the Mabari. A dog similar to Pitbulls, but with very high intelligence, versatility, and even more strength, speed and energy.
They are still a common sight beside humans, living with them and being their loyal friends. There are still more feral dogs that lives in the Zone, and will attack humans on sight.