Passive immunization

Immediate protection of an animal can be achieved by passive immunization—the administration of preformed antibodies to a susceptible animal. These antibodies have historically been produced in hyperimmunized horses. The most widely employed are antitoxins directed against clostridia, such as tetanus or botulism, and snake venoms. Polyclonal antibodies are also administered to neonatal animals to protect against infections such as Rhodococcus equi in foals. Monoclonal antibodies are more specific reagents that are currently being used for the treatment of atopic dermatitis, certain cancers, and selected infectious diseases. Intravenous immunoglobulins are being used to treat autoimmune diseases.