Rabies vaccination is required by law in nearly all areas. Even though protection from rabies is documented to last at least three years, current law in some states or areas still requires that boosters be given annually or biannually rather than the standard policy of every three years. However, vaccination against rabies virus is occasionally associated with debilitating adverse effects. According to the CDC domestic animals account for less than 10% of the reported rabies cases, with cats, cattle, and dogs most often reported rabid. Scientific data indicate that vaccinating dogs against rabies every three years, as most states require, is unnecessary.