Cal. Food & Agric. Code § 24106

(a) Before an animal may be sold at an auction, the operator of the auction yard shall determine whether the animal has an implanted microchip or has been tattooed or branded with an identifying mark. If the animal has an implanted microchip, a tattoo, or a brand, the operator of the auction yard shall post, on its internet website and through any active social media in which the operator of the auction yard participates, all identifying information, including any identification number contained in the microchip and a detailed description or picture of any tattoo or brand found on the animal. This information shall remain on the auction yard operator’s internet website and on the page of any active social media in which the operator of the auction yard participates for at least 24 hours after the initial posting.
(b) No person shall purchase, consign, sell, or accept the donation of an animal at a public or private auction unless the seller or donor of the animal provides, and the purchaser or donee receives, at the time of delivery, a written bill of sale or any written instrument that contains all of the following information:
1. (1) A description of each animal that is sold that includes its sex, breed, color, approximate height and weight, approximate age, natural marks, or identifying scars, and of each brand or tattoo and its location. If the animal has been branded or tattooed and registered with the Bureau of Livestock Identification in the department, the identification papers shall accompany the animal.
2. (2) The name, address, signature, and motor vehicle driver’s license number of the person who sold or donated the animal.
3. (3) The date of the transaction.
4. (4) The name, address, and motor vehicle driver’s license number of the purchaser of the animal.
5. (5) The name, address, and motor vehicle driver’s license number of any person who transports the animal to the purchaser or an auction yard.
(c) Any person who purchases an animal at an auction described in subdivision (b) shall sign a sworn statement, under penalty of perjury, acknowledging and agreeing to comply with Sections 598c and 598d of the Penal Code.
(d) For a minimum of one year following the date of sale of each animal sold at auction, the operator of the auction yard shall maintain appropriate records that accurately document compliance with this section. The operator of the auction yard shall provide access to the records and documents identified in subdivisions (a), (b), and (c) upon the request of the department, a law enforcement officer, an animal control agency, or a humane officer appointed pursuant to Section 14502 of the Corporations Code.
(e) In addition to any other penalties available under law, a person who violates this section shall be subject to a civil penalty of one thousand dollars ($1,000) for the first offense and two thousand dollars ($2,000) for the second and each subsequent offense.