FreeTDS/DBD::Sybase

I was looking for some advice....
I've successfully compiled FreeTDS, and recompiled my DBD::Sybase and
stuck it in a private library. 
Every thing is working great,  I was able to add an entry to my
freetds.conf file and create a script that queried my SQL Server and
Sybase server.

So now I was playing around.  I moved freetds to a new location and
found that it broke unless I set my LD_LIBRARY_PATH ( No big deal). 

Here is the big  question.   I accidentally removed my private copy of
DBD::Sybase, yet everything worked, so Do I really need to compile DBD
against FreeTDS or is it sufficient to simply ensure that my freetds
libraries are first in my search path.

Thanks 

Ian