California Code, Business and Professions Code - BPC § 19583.7

In addition to any criteria set forth by a racing association, a thoroughbred or quarter horse that is four years of age or older that has not competed in a race or has previously raced but has not raced in the preceding 365 days shall not be allowed to race, unless the horse has passed an examination and a postwork official blood test or tests required by the official veterinarian or the equine medical director, administered by the official veterinarian or the equine medical director's designee.  The horse shall race within 30 days after meeting these requirements.  A thoroughbred or quarter horse that has not raced within 120 days but has raced within 365 days shall have an examination performed by the official veterinarian or the equine medical director's designee within 14 days before entry.  Based upon that examination, the official veterinarian or the equine medical director's designee may require the horse to work before being allowed to enter in a race.  If the horse is required to work, it shall meet the same requirements as a horse that is working to be taken off the Official Veterinarian's List, as specified in Section 19583.5 or any regulation adopted by the board pursuant to that section.