1. Infectious Disease

2. Johne’s Disease (Paratuberculosis) Causative agent: Mycobacterium paratuberculosis Extremely slow onset, chronic, progressive, incurable, fatal –minimum 18 months to clinical status –incubation period up to 10 years Prevalent in 20% of US herds 5-20% of ALL dairy cattle infected –25-30% of all herds –increasing in both dairy and beef –sheep, goats and deer also susceptible

3. International Prevalence Denmark: almost half of all herds test positive Holland: 50 –80% of herds infected? New Zealand: 16 – 50% of herds infected

4. History “Johne’s disease is not at all widespread. It does occur, however, and as the years go by it will become more and more common and will places a great tax on the cattle industry” Beach and Hastings 1922

5. Johne’s Disease (Paratuberculosis) Following calfhood exposure there is no evidence of infection for six months to several years –Rate of progression dependent on age, genetic background, nutritional status, management, etc

6. Johne’s symptoms Clinical status after “high stress” period –Progressive and fatal –Non-treatable Primarily affects intestine and associated lymph tissues Causes proliferation of intestinal tissue –Malabsorption diarrhea –Animal loses condition –Displays diarrhea and constipation –Decreased milk, same feed intake (until late stages)

7. Fig 35-1. Cows with Johne's disease typically lose tremendous amounts of body weight, although feed consumption may be normal (Courtesy of Mark Kirkpatrick)

8. Johne’s Disease (Paratuberculosis) Apparently healthy animals can spread the disease –Test at regular intervals of 3-6 months –Diagnostic testing is often inaccurate –Fecal culture is most accurate method in live animals False negatives are still a problem No treatment –Prevention through keeping infected animals isolated

9. Johne’s Transmission Fecal-oral –Organism remains viable in feces for 6-11 months Transplacental transfer Organism present in milk, colostrum Severity of infection depends on level of infective dose Age of exposure is critical <5% of infected animals develop clinical symptoms

10. Age Effects Newborn calf most susceptible –susceptibility decreases with age –not clinical - no shedding until > 9 mos. Cows least susceptible –infection unlikely after 1 year of age –shedding rate highest in mature, clinically infected cows

11. Costs Lost milk costs Lost cow value and slaughter value Lost marketing ability of herd Longer calving intervals Increased mastitis Increased vet costs $250/cow (all cows, not just infected) Infected 100 cow herd with average infection rate loses $25,000/year

12. Antibody Tests

13. Fig 35-2. Enzyme-linked immunosorbent assays (ELISA's) are a useful diagnostic tool for estimating the prevalence of Johne's disease in infected herds (Courtesy of Mark Kirkpatrick)

14. Testing ELISA’s and other antibody tests have high incidence of “false positives” –If ELISA or antibody test is positive, fecal culture should be used to confirm status Fecal cultures take 16 weeks, very expensive –Negative result does not necessarily indicate uninfected cow, just non-shedding cow –Positive result is fairly accurate

15. Fig 35-3. To confirm infection with Johne's disease, tissues can be stained for the immunohistological detection of M. paratuberculosis (Courtesy of Mark Kirkpatrick)

16. Johne’s Disease (Paratuberculosis) Control measures for infected herd –Reduce contamination by good sanitation –Do not spread manure on pasture land –Raise young stock in uncontaminated environment, separate from mature animals

17. Control Program Prevent transmission –sanitary maternity barn –clean perineal area and udder –Remove calf from dam prior to nursing, wash udder well prior to milking –feed colostrum from test-negative cows –raise “shedders” separate from “susceptibles” –spread manure on crop ground, not pasture

18. Control Program Reduce incidence in herd –test mature animals every 6 months –remove test-positive animals immediately –cull any apparent clinicals regardless of test results –purchase only from tested clean herds –vaccinate infected herds not cost-effective in clean herds does not prevent disease, only reduces severity interferes with antibody tests

20. Is Johnes a Food Safety Issue? Crohn’s disease is a bowel disease in humans Overall incidence 5.6 cases per 100,000 Severe and very unpleasant condition Cause unknown, maybe infectious agent like Mycoplasma Johnes organism found in Crohn’s patients No firm link established, the evidence is still inconclusive - but the issue is a source of concern to the dairy industry

21. Bovine Virus Diarrhea (BVD) Incubation period of 7-9 days Characterized by –High temperature (105-107 F) –Nasal discharge –Rapid breathing –Loss of appetite –Diarrhea Causes abortions in pregnant cows (3-6 weeks after infection) Decrease in milk production in lactating cows

22. Bovine Virus Diarrhea (BVD) Prevention –Avoid contact with infected animals –Keep away from contaminated feed and water –Isolate all incoming animals for 30 days Treatment –Electrolytes –Antibiotics combat the secondary bacterial invaders

23. Bovine Virus Diarrhea (BVD) If BVD is a constant problem, vaccinate animals –Intramuscular administration of modified live or inactivated vaccines One vaccination should last a lifetime DO NOT vaccinate pregnant cows –Causes abortions DO NOT vaccinate calves under 6 months of age –Ineffective due to interference from maternal antibodies from colostrum Replacement heifers should be vaccinated at 9-12 months of age

24. BVD control Multiple strains exist (identify!) Fecal-oral –Sanitation crucial Vaccines highly effective –not 100% BVD-PI (persistently infected) are exceptional situation

25. BVD-PI animals 1 in every 200 calves is PI Infected in utero between 80 and 120 days Infection from 120-150 days –congenital defects –weak calf syndrome Infection after 150 days –immune response –abortion, mummification

26. BVD-PI calves No immune response –recognizes virus as “self” permanently Virus replication unchecked –incredibly high shedding rates –potential threat to entire operation Difficult to identify –Ab titers ineffective method –must directly test for presence of virus

27. Fig 35-4. Obtaining an ear notch tissue sample for immunohistochemical diagnosis of BVD infection (Courtesy of Mark Kirkpatrick)

28. Fig 35-5. Immunohistochemical techniques help veterinarians visualize the BVD virus in ear tissue (Courtesy of Mark Kirkpatrick)

29. Salmonella Invasive coliform –fecal-oral transmission –penetrates gut lining –systemic infection common Present on up to 75% of dairies –clinical expression after stress (shipping) Highly rate of transmission –“herd epidemics” common –high shedding rate –high mortality rate

30. Salmonella Pathogen associated with stress and immunocompromised animals –Calves and transition cows most susceptible maternity barn sanitation isolation of sick or recently purchased animals Characterized by rapid onset and severe watery diarrhea –Weak and rapidly dehydrated –Often becomes systemic infection Pathogen transmitted in feces –High sanitation standards are critical Infected cattle should be isolated –Animals are responsive to antibiotics

31. Challenges Some strains infect people Carriers include pets and pests Different strains present in different herds –S. typhimirium DT 104 is problem pathogen multiple antibiotic resistance (cassette resistance) resistant to ampicillin, florfenicol, streptomycin, sulphonamides, and tetracyclines use of one antibiotic selects for the rest

32. Treatment Identify early Isolate infected animals Extreme sanitary measures –cows AND people Use appropriate antibiotic treatment –test for susceptibility Supplemental fluids crucial Use herd-specific vaccine if necessary

33. Drenching Fluids

34. Bovine Respiratory Disease Complex (BRDC) Acute respiratory disease –Most common in calves –Commonly associated with transportation stress First sign of disease is a tired appearance and reduced appetite –Depression, nasal discharge, high temperature, cough, rapid breathing –Loss of appetite, then loss of body weight and milk production

35. Bovine Respiratory Disease Complex (BRDC) Caused from multiple infection due to interaction of viruses and bacteria –Accentuated by environmental conditions and stress Three main causative viruses –Infectious bovine rhinotracheitis –Bovine virus diarrhea –Parainfluenza

36. Fig 35-6. Adequate ventilation is one of the most important considerations for the prevention of bovine respiratory disease complex in dairy cattle (Courtesy of USDA)

37. Bovine Respiratory Disease Complex (BRDC) Immunity against the three main viruses can be achieved –Modified live or inactive vaccines, in single or combination forms Treatments, if given early in the course of disease, are effective –Antibiotics and sulfa drugs

38. Fig 35-7. For this ELISA test for BRSV virus, the intensity of the blue color is proportionate to the titer of specific antibody in the sample (Courtesy of Mark Kirkpatrick)

39. Pneumonia Inflammation of lungs in which the air sacs fill with discharge –Often a disease secondary to other conditions If left untreated, 50-75% of animals die Characterized by elevated temperature –Quick shallow breaths, nasal discharge, cough, no appetite

40. Fig 35-8. Fever, dullness, inappetance, coughing, and nasal discharge are the most common symptoms of pneumonia in calves (Courtesy of University of Illinois)

41. Pneumonia Causes are numerous –Many microorganisms and many different viruses –Changeable weather and poorly ventilated damp barns are conducive to pneumonia Prevention –Providing good hygienic surroundings with adequate ventilation Segregate sick animals Treat sick calves with broad spectrum antibiotics

42. Pinkeye (Keratitis) Several causes - two most common types, one caused by virus, one by bacteria Characterized by liberal flow of tears and inability to keep eye open –Redness and swelling of the membrane lining of eye If untreated can cause blindness

43. Pinkeye (Keratitis) In viral pinkeye, causative organism is infectious bovine rhinotracheitis –Eyeball is only slightly affected –Mainly affects eyelids and tissues surrounding the eye –Occurs most frequently in winter –Highly contagious by direct or indirect contact –Prevention Proper vaccination prior to disease onset –Treatment is seldom of value

44. Pinkeye (Keratitis) Bacterial pinkeye caused by Moraxella bovis –Produces a toxin that irritates and erodes the coverings of the eye –Occurs mainly in warm weather –Transmission mainly by flies and direct contact between animals –Prevention Controlling face flies, isolate infected animals

45. Pinkeye (Keratitis) Bacterial pinkeye treatment: –Application of antibiotics or sulfa drugs to the affected eye –Cortisone injected into eye can reduce swelling –Eye patch –Isolate animal

46. Ringworm Contagious disease of the outer layers of skin Caused by microscopic molds or fungi Characteristics –Incubation period of one week –Round scaly patches of skin, devoid of hair Organisms spread between animals –Must disinfect surfaces as well as treat animals –Isolate infected animals

47. Coccidiosis Parasitic disease caused by microscopic organisms called coccidia –Cattle infected by 21 species of coccidia Only Eimeria bovis and Eimeria zuerni cause the most serious infections –Infected animals pass organism through feces Gains entry into an animal by being swallowed In the host’s intestine the outer membrane of oocyte ruptures, releasing the sporozoites which destroy epithelial cells

48. Coccidiosis Severe infection produces diarrhea and bloody feces –Hemorrhage of blood vessels into intestinal lumen –Segregate infected animals immediately Try to keep feed/water from being contaminated

49. Foot and Mouth Disease (FMD) Highly contagious disease of cloven-footed animals –Humans are mildly susceptible Characterized by appearance of watery blisters in mouth and on skin between claws of the hoof –Moderate fever, excessive salivation

50. Fig 35-9. Foot and mouth disease (FMD) is characterized by blister-like vesicles on the tongue and lips, mouth, on the teats, and between the hooves (Courtesy of USDA)

51. Fig 35-10. The blisters in the mouth and on the tongue caused by foot and mouth disease result in excessive slobbering (Courtesy of USDA)

52. Foot and Mouth Disease (FMD) Infective agent is a small virus –Six different strains –Virus is present in blisters, blood, milk, meat, saliva, and urine of infected animals Can be spread through infected biological products and by cattle fever ticks

53. Anaplasmosis Caused by parasite, Anaplasma marginale –Invades red blood cells –Transmitted by biting insects Once infected, the animal permanently retains parasite in blood –No signs of ill health may be evident –Clinical symptoms generally do not appear until 18 months of age Calves usually only have mild symptoms

54. Anaplasmosis In mature animals –Symptoms of anemia and jaundice skin –Rapid heart rate, labored breathing, fever, loss of appetite –Recovery is usually slow, yet the animal still retains the parasite

55. HBS - One Syndrome with Several Names HBS: Hemorrhagic bowel syndrome JHS: Jejunal hemorrage syndrome BBS: Bloody bowel syndrome

56. Hemorrhagic Bowel Syndrome Sporadic in morbidity A typical case incidence rate is 2-3%, with some farms experiencing an outbreak form Mortality may approach 85-100% of cases due to peracute nature

57. Clinical Signs of “HBS” Short incubation period – hours rather than days Severe sweats Bruxism (teeth grinding) Sternal recumbancy Lethargy (extreme depression) Enopthalmia (sunken eyes)

58. Clinical Signs of “HBS” Slight bloating may be evident Pale mucous membranes Fluid slosh in lower right abdomen Distended gut loops per rectal palpation SUDDEN DEATH

59. Post-Mortem Findings Severe segmental small intestinal inflammation Segmental hemorrhaging and clotting forming a functional plug.  Necrosis +/-  Impaction

63. Diagnostics Appearance of characteristic lesions and clinical signs Isolation of Clostridium perfringens type A from the lesion site in high numbers. Overgrowth occurs fast. Fecal cultures not diagnostic

64. Treatment Efforts Prognosis is extremely poor Surgical intervention  Some areas of segmental clots may be massaged out to resolve the case  Intestinal resection & anastamosis is usually required to remove affected tissue –Success Rate ~ 5-10%

65. Are Clostridial species involved? –C. perfringens type A has to be present in the diet to cause disease –Readily fermentable carbohydrate is needed to support growth & sporulate –Partial slowdown or stoppage of ingesta flow allowing proliferation of C. perfringens. –Generation time = 8.8 min.

66. Field Observations Model of Infection Lamb Enterotoxemia: Carbohydrate engorgement or presence in small intestine in high amounts. Gut Physiology? Rumen emptying rates, local hypomotility? Serum Ca levels? Food Poisoning: Is there a source of C. perfringens type A (human model)?

67. Herd Breaks Fermentable Carbohydrate –NFC levels in excess of 40%? –Which high moisture feeds are being used in the ration and at what levels? –How soluble are the starches? Wet vs. Dry Fermented Fineness of Grind

68. Vaccination? Commercial Vaccines: 7-way Clostridial bacterin/toxoid  Vaccination with a 7-way Clostridial bacterin/toxoid has shown little effect. C. perfringens C&D toxoid  C. perfringens C&D toxoid may have some effects if the infection was mixed.

69. Summary Feed Contamination Poor fermentation Contamination Carbohydrate availability Acidosis? Rumen Emptying Rate? Intestinal Motility Ca Levels, DMI or Acidosis

70. Reproductive Diseases and Disorders

71. Brucellosis (Bang’s Disease) Causative bacteria: Brucella melitensis –Contagious abortion disease in cattle, Brucella abortus Hidden, lesions frequently are not evident –In other species, can cause similar problems National testing program –Control and eradication has helped lower infection rates

72. Brucellosis (Bang’s Disease) Symptoms are indefinite –Abortions in cattle, but not all animals infected will abort –Infected animal may have a normal birth, but calf may be weak, milk production reduced –Joint pain, abcesses Humans are susceptible to all three species of brucellosis –Swine organism causes most severe disease Undulant fever caught by handling affected animals, raw meat or milk

73. Brucellosis (Bang’s Disease) Brucella organism is resistant to drying –Killed by disinfectants and pasteurization –Found in tissues, membranes, and fluids, of the aborted young –Harbored indefinitely in the udder Brucellosis is contagious –Licking infected animals –Through contaminated feed/water

74. Brucellosis (Bang’s Disease) Control programs –Testing –Removal of infected animals –Strict sanitation Brucellosis eradication program (1934) –Finding infected animals and eliminating them –Vaccinating where there is a disease problem –Certifying brucellosis-free herds and areas –Providing indemnity to farmers whose animals are condemned under the program

75. Leptospirosis Humans can contract disease through skin abrasions when handling infected animals, raw meat or milk Usually a mild disease –Fever, poor appetite, abortion, ropy milk Caused by several species of corkscrew shaped organisms

76. Fig 36-1. Leptospirosis can cause abortions during the last half of gestation (Courtesy of USDA)

77. Leptospirosis Preventative measures –Test animals prior to purchase, isolate for 30 days, then retest –Keep premises clean –Control rodents and other vectors (canines) –Vaccinate susceptible animals annually if disease is present in the area

78. Leptospirosis Carrier animals spread the infection by shedding organism in their urine –Recovered animals remain carriers for 2-3 months

79. Vibriosis Infectious venereal disease –Causes infertility and abortion –Must be diagnosed through laboratory Caused by Campylobacter fetus Prevention –Avoid contact with diseased animals and contaminated feed, water, and materials –Vaccinate annually –Artificial insemination

80. Bovine Trichomoniasis Protozoan venereal disease –Causes early abortions and temporary sterility Caused by Trichomonias foetus –Found in aborted fetuses, fetal membranes and fluids, vaginal secretions –Infected bull is source of infection Disease is self limiting in cows Signs not shown in bulls, but cows indicate infection Prevention: use clean bulls or AI

81. Fig 36-2. This bull, infected with trichomoniasis, appears normal and will breed normally, but can infect an entire herd through natural service (Courtesy of University of Illinois)

82. Metritis Inflammation of uterus caused by various bacteria –Usually develops after giving birth Symptoms –Foul smelling discharge from vulva, brown color –High temperature, rapid breathing, loss of appetite, lowered milk production Affected animals may die in 1-2 days or acute infection may cause sterility

83. Metritis Most commonly caused by Escherichia coli Preventative measures –Alleviate predisposing factors Bruises and tears while giving birth Exposure to wet and cold Introduction of bacteria during or after birth

84. Bovine Protozoal Abortion Not all infected cows will abort –Calves born from infected cows will experience nervous system disease Caused by Neospora –Transmitted through congenital infection and fecal-oral transmission

85. Foothill Abortion Reported in western US and Europe Cows abort when 3-6 months pregnant –Some calves are stillborn while others are weak at birth Caused by a virus –A soft bodied tick is the vector Prevention –Move cattle out of tick-infested areas during 3-6 month gestation period –Animals that have aborted are usually immune and can be returned to herd