I looked on Amazon.com, and they have a couple of books in Spanish that may be approprite, I'm not sure. But you are in San Diego, a Spanish-named city in a state with many bilingual people, Is there a Spanish-language bookstore that might be able to help you? Even a basic children's book, in Spanish, might not only help the dog, but the family as well. Failing that, a simple book with not too many words, might be a good way to start a conversation. Failing all that, might your city have a friendly person at an ASPCA that speaks Spanish and has some materials on proper pet care?