List of values accepted by a column
You can check the condition of the check constraint from all_constraints or user_constraints view. 

SQL&gt; create table animal(
SR_ID number, 
First_Name varchar2(20), 
Last_Name varchar2(20), 
PET varchar2(20) constraint ckpet check (PET in ('DOG', 'CAT', 'FISH'))
);

Table created.

SQL&gt; select constraint_name,search_condition 
from all_constraints
where table_name='ANIMAL'
and constraint_type='C'; 

CONSTRAINT_NAME     SEARCH_CONDITION
---------------     ---------------------------
CKPET                PET in ('DOG', 'CAT', 'FISH')