CA Dept. of Social Services: The Assistance Dog Special Allowance (ADSA) Program provides a monthly payment of $50 to eligible persons who use a guide, signal, or service dog to help them with needs related to their physical disabilities, to help pay costs of food, grooming, and health care.
The San Diego Food Bank: (though this program is "unofficial" they get enough pet food to distribute to those in need) 9850 Distribution Ave, San Diego, CA 92121 (858) 527-1419