Rabbits are the most commonly used laboratory animal for antibody production.
Goats, guinea pigs, chickens, and sheep are also used frequently. The first injection of antigen is generally given in an aggregated form because most soluble proteins are poor immunogens. Use of an adjuvant, therefore, is generally used for injection of soluble antigens. Reinjection of CFA into a sensitized animal causes hypersensitivity reactions that can be painful. The use of multiple injections with CFA is rarely warranted and must be justified by the investigator.