Cal. Health & Safety Code § 122210

(a) No dog may be offered for sale by a pet dealer to a purchaser until the dog has been examined by a veterinarian licensed in this state. Each dog shall be examined within five days of receipt of the dog and once every 15 days thereafter while the dog is in the possession or custody of the pet dealer. The pet dealer shall provide any sick dog with proper veterinary care without delay.
(b) Any dog diagnosed with a contagious or infectious disease, illness, or condition shall be caged separately from healthy dogs until a licensed veterinarian determines that the dog is free from contagion or infection. The area shall meet the following conditions when contagious or infectious dogs are present:
1. (1) The area shall not be used to house other healthy dogs or new arrivals awaiting the required veterinary examination.
2. (2) The area shall not be used for storing open food containers or bowls, dishes, or other utensils that come in contact with healthy dogs.
3. (3) The area shall have an exhaust fan that creates air movement from the isolation area to an area outside the premises of the pet dealer. The removal of exhaust air from the isolation area may be accomplished by the use of existing heating and air-conditioning ducts, provided no exhaust air is permitted to enter or mix with fresh air for use by the general animal population.
4. (4) Upon removal of all of the contagious or infectious dogs, the area shall be cleaned and disinfected before any healthy animal can be placed in the area.
(c) If the pet dealer’s veterinarian deems the dog to be unfit for purchase due to a disease, illness, or congenital condition, any of which is fatal or that causes, or is likely to cause, the dog to unduly suffer, the veterinarian shall humanely euthanize the dog. The veterinarian shall provide the pet dealer with a written statement as to why the dog was euthanized. Otherwise, the pet dealer shall have a veterinarian treat the dog, or may surrender the dog to a humane organization that consents to the receipt thereof.
(d) In the event a dog is returned to a pet dealer due to illness, disease, or a congenital or hereditary condition requiring veterinary care, the pet dealer shall provide the dog with proper veterinary care.