Cal. Bus. & Prof. Code § 4920.1

For purposes of liability pursuant to this article, the production and use of whole blood, plasma, blood products, and blood derivatives for purposes of injecting or transfusing the same, or any of them, into an animal shall be construed to be, and is declared to be, the rendition of a service by each and every person, firm, or corporation participating therein, and shall not be construed to be, and is declared not to be, a sale of that whole blood, plasma, blood products, or blood derivatives.