Many studies have been carried out to investigate the immune pathways stimulated by adjuvants, the role of adjuvants in enhancing pathogen-specific immune responses, and the potential noxious effects of adjuvants for the recipient, both in animal models and in humans. In order to prevent several costly infectious diseases, farmed salmon are intraperitoneally injected with vaccines containing adjuvant oil and a number of different antigens. The rabbit model is often used for vaccines intended for intramuscular injection. The adjuvants were inoculated in swine neck, quadriceps, and semitendinosus muscles. Several kinds of animal models have been employed to investigate adjuvant effects and midterm reactions in vivo, in an attempt to better unravel adverse events in humans following vaccinations or prosthesis implantations. Higher organisms, such as primates, are rarely used; rather, different mouse models have provided the bulk of the evidence for vaccine and adjuvants effects in living beings.