We just returned from helping the animals at the Katrina disaster.
We worked in the Gonzoles site where rescued pets were brought for veterinary care, decontamination, food, water, and shelter. There were literally thousands of animals when we left. At that time they were still asking for assistance caring for the animals. Work was already started reuniting animals with family and shipping other animals into foster environments.
If you want to donate time or money to assisting the animals contact the Humane Society or the SPCA as they seemed to be the two organizations in charge. If you want to donate funds to assist, stick to 503c organizations and send it with a letter specifying how you expect the organization to use your money so it does not just end up in the general fund.