Welcome to Pet Talk. You'll find a great source of support and love here. Although I have not experience with this, Nomilynn can provide you with alot of info. She did post these links awhile back that explains the disease.

http://www.sniksnak.com/cathealth/chylothorax.html

http://rev.tamu.edu/stories/02/091902-3.html

http://www.acatclinic.com/library/CHYLO.htm

Sounds like a good idea to go back to the vet. Please keep us posted and BTW Garp is very handsome. Did I mention that we love to see lots and lots of pictures??