The five words below can be changed into new ones according to a certain pattern. Can you determine what it is?

BUN
DOG
TOP
RAP
LENT

HINTS:
#1: Easter animal
#2: Two letters can be added to each clue word.

Answers:

Each word can be followed by the two letters of a U.S. state postal abbreviation to make a new word. 

BUNNY
DOGMA
TOPAZ
RAPID
LENTIL 

Credit:
NY Times Crossword
February 5, 2012
Charles M. Deber
STATE ANNEXATION

NOTE: See the first half of this puzzle - posted 2-16-17