Wal-Mart is a good resource for purchasing medications for your pet.
www.hsus.org: Scroll down down to the bottom and click on this helpful article on the bottom of the list; includes a list of organizations for financial assistance
This program offers a revolving line of credit for veterinary expenses. You can also call them at: 800-677-0718
Has a list of Vets at various locations. You may want to call around and compare their rates for the vet care you need for your pet.