Excel 2007 : creating part #'s from words in drop down

I have a workbook with two sheets. one sheet has the contents of the drop downs, and in the second sheet I have the drop downs "I used data validation". I would like to have the words in my drop down be equal to numbers. like: say I have three choices in one of my drop downs
cat
dog
lion

cat being the first in the drop down would be equal to 001
dog being the second in the drop down would equal to 002
lion being the third in the drop down would be equal to 003
I have 6 dropdowns total for now so when I pick the six that I want I will get this:
00x-00x-00x-00x-00x-00x in a certain cell "x being whatever I the word corresponds to".
is this possible and if so how? thanks in advance