- - AGRICULTURE CORE CURRICULUM - - (CLF3000) Advanced Core Cluster: ANIMAL SCIENCE (CLF3300) Unit Title: ANIMAL HEALTH ____________________________________________________________________________ (CLF3301) Topic: DISEASE FIGHTING Time Year(s) AGENTS 2 hours 3 / 4 ____________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the student will be able to: Learning Outcome #: (E-1) - Describe the differences between vaccines, anti- serum, and bacterins and explain how each is used to fight disease. Special Materials and Equipment: Samples of biological preparations such as vaccines, toxoids, and bacterins. References: Baker, James, and William, Greer. (1981). ANIMAL HEALTH (2nd ed.). California Vocational Curriculum Guidelines, ANIMAL PRODUCTION, "Animal Health", Vol. 1. Meyer, Norvan L. 1984 YEARBOOK OF AGRICULTURE. Evaluation: Quiz by instructor. TOPIC PRESENTATION: DISEASE FIGHTING AGENTS REVIEW: Basic Core, Animal Health CLF276 and CLF277. A. Types of Immunity Systems 1. Acquired immunity occurs by exposure to pathogenic organisms or by immunization after birth. There are two types of acquired immunity. a. Passive immunity: Temporary immunity where the animal acquires antibodies from an outside source such as colostrum or by transferring antibodies from an immunized animal to a susceptible one with serum. b. Active immunity: The animal develops antibodies in response to direct contact with specific disease-causing organisms. Animals need 1-2 weeks from the vaccination to acquire active immunity. B. Vaccination 1. The mechanical act of injecting some agent (such as a bacterin, toxoid, or vaccine) into an animal for the purpose of disease prevention and developing immunity in the animal. a. Biologicals, biologics, or biological preparations are all terms that could cover materials used for vaccination. C. Types of Biological Agents 1. Antigens or antibodies: The antibodies of diseases whose causative organisms have been identified. Organisms are prepared so that an animal may be injected with them for protection from diseases which they have not been exposed to. 2. Bacterin: a. A type of vaccine prepared from disease causing organisms (bacteria) that have been killed. b. "Mixed bacterins" contain more than 1 kind of killed bacteria. c. These dead pathogens are injected into the animal and cause it to manufacture antibodies against that disease and stimulate immunity. d. This is an example of "active acquired immunity." 3. Vaccines: a. Made from living organisms (bacteria or viruses) that have been weakened or changed so as to lose much of their original virulence (disease causing ability). 1) Upon injection the animal gets a mild case of the disease. 2) The animal's body then produces antibodies against the disease which often results in permanent immunity. 3) Animals susceptible to a disease should be vaccinated with a vaccine when they are healthy. 4) This is another example of "active acquired immunity." b. Types of vaccines: These vaccines or immunizing agents are manufactured under exacting conditions which provide safe and effective means of protecting livestock against invaders. 1) Bacterial vaccines - a) are made from bacteria of an infectious nature, and b) are weaker than viral vaccines. 2) Viral vaccines, must be grown in living tissue such as lab animals, embryonated eggs, or cultures of living cells. a) There are three types of these biological agents: i) Live modified virus vaccines, - are modified by passage through unnatural hosts (chick embryo, ferrets), - lose virulence for the natural host and become adapted to the new host, - stimulate antibody formation in an animal that has no disease symptoms, and - are used in parainfluenza3, infectious bovine rhinotracheitis, and rhinitis in swine. ii) Live unmodified virus vaccines, - mean that the animal will not contract the disease, but the living viruses will stimulate antibody production against a specific virus. iii) Killed viruses, - stimulate active immunity, and - are used in sleeping sickness and equine influenza. 4. Anti-Serums (an immunizing agent): a. Contain no organisms - dead or alive. b. They are made from infecting a donor animal with the disease for which the serum is desired, or by vaccination. 1) The antibodies form in the blood, and 2) the blood is withdrawn and anti-serum is recovered from the blood. c. The antiserum give a 2-4 weeks of protection to animals continually exposed to a disease. The organism causes the animal to develop a high level of immunity which offers temporary protection. d. The injection of anti-serum does not cause the animal to produce antibodies, therefore it gives only temporary immunity. e. This is an example of "passive acquired immunity". 5. Toxoids: a. Toxoids are inactivated toxins obtained from toxin-producing organisms grown in the laboratory which stimulate a strong active immunity in the injected animal. __________________________________________________________ ACTIVITY: 1. Discuss samples of biological preparations, the diseases they prevent, and when they should be administered. 2. To reinforce the understanding of these disease fighting agents a discussion on some of the pioneers of modern medicine such as the Pasteurs would be appropriate. An alternative would be to discuss the fight to cure polio. (Note be prepared to discuss related issues such as the use of live animals in research, etc.) __________________________________________________________ 5/4/90sg #%&C