Cana landlord be sued ifa tenant’sdog bites someone?

The answer is - maybe.  As usual it depends upon the circumstances.  First of all, the applicable CA statute says that the owner of a dog (not anyone else) is responsible for the damages suffered due to their dog biting a person not.  However, what about a claim of negligence?  Well if the landlord did not even know a dog was on the property then theyare probably not on the hook (but see nuisance below).  Even if the landlord knew the tenant had the dog but the dog had no history of viciousness and was not a known dangerous breed, then the landlord is most likely not on the hook.  However if the landlord knew the dog was on the property and knew that the dog had a history viciousness, their liability is now more probable.  Basically, this is premises liability which may hold the landowner responsible for hazards on the property.  Additionally, the landlord may be liable under a claim of "nuisance".  There is case law in CA that suggests that a landowner may be liable for a nuisance even if the landowner was not aware of the nuisance. 

The fact is that no matter what the situation, even if a landlord is ultimately found not to be liable for a tenant's dog attack, that does not mean a landlord will not be sued and have to defend thenself in a lawsuit.  And this is so, even if a tenant has insurance; a landlord can be sued just because they may have "deep pockets".