This can be tough. Common law applies instead of strict liability law. Under California law, in some instances, a landlord can be responsible for dogs owned by their tenants. In order to this, it can be difficult, because you have to prove the landlord knows of the dog, and also knows that it has dangerous propensities. See my discussion under more FAQ's, Blogs, and Legal Articles on this website on how to prove California landlord liability with dog bites.
HERE IS A QUICK VIDEO ON LANDLORDS AND CALIFORNIA DOG BITES: