Understanding Animal Diseases: Bacteria, Viruses, and Prevention

1. Animal Diseases Modified by Georgia Agricultural Education Office June, 2002

2. Disease • Broad definition – not being at ease or uncomfortable • Producers have a vested interest to keep their animals healthy

3. Healthy Animals • Grow faster and produce more profit for their owners • Some diseases are mild, others may be severe and cause rapid death

4. Sick animals • Usually display outward signs of illness • Animal may be droopy, go off feed and water, be restless, have a dull haircoat

5. Infectious diseases • Caused by microorganisms that invade the animal’s body • Usually contagious diseases that the animal can pass to another animal

6. Bacteria • Live in a wide range of conditions • Live on and in the bodies of all animals • More numerous than the cells of the body

7. Bacteria • Many are beneficial • Those living in the stomachs of ruminant animals aid in digestion

8. Bacteria • Useful in production of foods such as cheese and sauerkraut • Many can be harmful • Invade the cells of an animal’s body

9. Parasitic bacteria • May harm the animal by feeding off the body cells or secreting a material known as a toxin

10. Toxin • Substance that causes harm to an organism • A poison

11. Harmful bacteria • When large numbers invade, the animal becomes ill • Type and form of the illness depends on the type of bacteria that invades the animal

12. Cocci • Round spherical shaped bacteria • Some forms of pneumonia and strep are caused by this bacteria

13. Bacillus • Rod shaped • Single, pairs, or arranged in chains • Cause some serious diseases in animals

14. Bacillus • Anthrax • Tetanus • Blackleg • Intestinal coliform • Salmonella and tuberculosis

15. Spirilla • Shaped like spirals or corkscrews • Very motile • Require moist atmosphere to live

16. Spirilla • Live very well in the reproductive tracts of animals • Leptospirosis • Vibrosis and spirochetosis

17. Most bacteria • Can be controlled by the use of antibiotics • Penicillin was one of the first • Produced from extracts of molds

18. Penicillin • Many forms are now produced • Very effective against bacterial infection.

19. Viruses • Very tiny particle of matter composed of a core of nucleic acid and a covering of protein that protects the virus

20. Viruses • Have characteristics of both living and nonliving material • Are on the borderline between living and non living

21. Viruses • Made up of some of the material found in cells but are not cells because they do not have a nucleus or other cell parts.

22. Viruses • Do not grow and cannot reproduce outside a living cell • Once inside a living cell, virus reproduces using energy and materials in the invaded cell

23. Viruses • Harm cells by causing them to burst during reproduction • And by using material that the cell needs to function properly

24. Virus • Viral diseases cause the animal to be sick by preventing certain cells in the body from functioning properly

25. Virus • More difficult to treat than bacterial diseases • Antibiotics are not effective against viral infections

26. Viral diseases • Foot and mouth disease • Influenza • Hog cholera • Pseudorabies

27. Viral diseases • Best means of dealing with them is prevention

28. Protozoa • Microorganism that causes disease • Single celled organisms that are often parasitic

29. Protozoa • Cause harm by feeding on cells or producing toxins • African sleeping sickness • Anaplasmosis

30. Protozoa • Coccidiosis • One of the most costly poultry diseases • Caused diarrhea and weight loss

31. Protozoa • Most can be controlled by drugs

32. The immune system • Several lines of defense in fighting disease • Physical barriers that keep pathogens out

33. The immune system • Nostrils are lined with hairs that attract particles that harbor germs before they can enter the body

34. The immune system • Mucous membranes secrete viscous water substance that traps and destroys bacteria and viruses

35. The immune system • Digestive and respiratory systems – greatest avenue for entry • Some disease germs can live in the soil for many years

36. Soil borne disease • Animals come into contact with the ground when they graze • Many pathogens are breathed in by livestock

37. Germs • Swallowed by animals are destroyed by digestive enzymes • Inhaled germs are trapped in mucous membranes of respiratory tract

38. 2nd line of defense • Blood cells • White and Red • Red – carry oxygen and other nutrients to other body cells

39. White Blood Cells • Are produced in the bone marrow • Circulate throughout the body to get rid of worn out cells

40. Phagocytes • White blood cells that intercept and destroy pathogens • Also migrate to certain organs and remain there to intercept pathogens

41. White Blood Cells • Circulate through other body fluids and the mucous membranes

42. Phagocytes • Release chemicals that can induce the production of more white blood cells to help fight disease

43. Phagocytes • An elevated WBC count indicated that there are disease organisms present in the animal’s body and a large number of phagocytes have been produced to combat them

44. Lymphocytes • Lymph glands that produce certain WBC’s • These cells react to foreign substances by releasing chemicals that kill the pathogen or inactivate the foreign substance

45. Antigens • Substances that cause the release of chemicals • May be viruses, bacteria, toxins, or other substances

46. Antibodies • The chemicals released by the lymphocytes

47. 2nd Immune Response • Lymphocytes become memory cell and are ready to release the antibody if the antigen enters the body at a later time

48. 2nd Immune Response • Response occurs much more quickly • Lasts longer than primary response

49. Immunity • Means than an animal is protected from catching a certain disease • Animal’s body is capable of producing enough antibodies fast enough to neutralize the disease

50. Immunity • Active or passive • Active –animal is more or less permanently immune • Passive – animal is only temporarily immune