Physiologic and behavioral assessment of rabbits immunized with Freund's complete adjuvant

Although the use of Freund's Complete Adjuvant (FCA) has been discouraged for the production of polyclonal antibodies, little clinical evidence supports the belief that FCA necessarily affects the well-being of immunized rabbits. We designed the present study to determine whether immunization at multiple sites with small volumes of Freund's adjuvant affects rabbit well-being. We injected 18 female New Zealand White rabbits (six animals per group) with antigen in FCA, Freund's Incomplete Adjuvant, or physiologic saline in the following volumes and routes: 0.02 to 0.03 mL intradermally in each of 30 to 40 sites and 0.1 mL subcutaneously in each of two sites. The body weight, temperature, complete blood count, and behavior of the rabbits in the home cage, upon handling, and in an open field did not differ significantly among the immunization groups during the 7-week assessment period. Only the degree of induration around injection sites differed: as expected, FCA induced the greatest response at the injection sites, but the sites were neither ulcerative nor necrotic, nor did palpation of the sites induce any apparent discomfort to the rabbits. We conclude that FCA may be used safely and humanely in rabbits if small volumes are injected intradermally or subcutaneously in multiple sites.