I'm sure you've done it, but do check the shelters. The firefighters were saving a lot of animals. And oddly enough, even people who had lost everything, had their animals safe. I've heard a few stories like that. Check all the shelters. Ones in Austin and Bastrop County, but also in the surrounding communities. The shelters were really taxed and so I'm sure some of them went to other shelters.
Check out this page on Facebook. Social media can be a big help in this situation. They have photos up there of pets they've found. You may also be able to give your information about your dogs.
http://www.facebook.com/pages/Urgent...888568?sk=wall
Another option is Craigslist. You can create your own ad about your dog, and also search on there. Craigslist even has a lost and found section for pets. Check these links.
http://austin.craigslist.org/laf/
http://austin.craigslist.org/pet/
One thing you can do, is on Craigslist just type in Catahoulas or Catahoula into the search. It'll pull up any ads containing those words. If there aren't any ads for the Austin area, it'll even search for surrounding areas like San Antonio and the Craigslist section for Killeen, etc.