Grandfather clause contributes to attack
From ANIMAL PEOPLE, November/December 2010:
DES LACS, N.D.–Grandfather clauses are a common feature of
animal control ordinances, included to ease the passage and initial
enforcement of provisions excluding poultry, livestock, exotic
pets, horses, or dogs of high-risk breed.
The underlying hope of a grandfather clause is that animals
who already live in a community when an ordinance is passed will be
minimally problematic if they are not replaced or augmented by others.