Lecture 29

• Shipping fever is also known as

  Pneumonic Pasteurellosis of cattle or Bovine Respiratory Diseases
• Pneumonic Pasteurellosis of cattle is an entity within the BRD complex, characterized by


  acute bronchopneumonia with toxemia
• Etiology of Shipping fever


  -Mannheimia haemolytica serotype A1 and A6

  -Pasterurella multocida serotype A3
• Epidemiology of shipping fever


  -young rapidly growing cattle, especially recently weaned beef calves placed in feedlot (shipping fever)

  -unweaned dairy calves (enzootic calf pneumonia)

  -can occur in nursing calves and mature cows
• What are some stressors that can cause shipping fever?


  -transportation

  -mixing animals from many different sources

  -weaning

  -processing procedures

  -ineffective ventilation of housed animals
• What are the signs?


  -acute respiratory disease

  -abnormal lung sounds

  -fever

  -toxemia

  -anorexia

  -sudden death

  -respond to treatment with antibiotics
• Lesions include


  acute fibrohemorrhagic pneumonia, frequently with pleuritis
• Diagnostic confirmation


  culture organism from lung and histopathology of lung
• Treatment includes


  antimicrobials; NSAIDs
• Control includes:


  -preconditioning programs

  -management strategies to reduce stress

  -Viral and bacterial vaccines
• What is the most important bacterial pathogen in weaned calves?


  Mannheimia haemolytica serotype A1 and A6
• What is commonly isolated from the lower respiratory tract of younger calves with respiratory disease?

  Pasteurella multocida serotype A3
• Characteristics of Pasteurellaceae


  -small

  -gram negative, bipolar rods

  -non-motile

  -oxidase positive
• What causes respiratory infections under stress?


  -Pasteurella multocida

  -Mannheimia haemolytica
• P. multocida Type A in cattle causes


  -bovine pneumonic pasteurellosis (shipping fever)

  -enzootic pneumonic complex of calves
• P. multocida Type A in pigs causes


  -pneumonia

  -atrophic rhinitis
• P. multocida Type D in pigs causes

  -Atrophic rhinitis

  -pneumonia
• M. haemolytica in cattle causes

  bovine pneumonic pasteurellosis (shipping fever)
• What age is shipping fever most common?

  young growing cattle from 6 months to 2 years of age (but all age groups are susceptible)
• Calves that are nonimmune to M. haemolytica and its leukotoxin (LKT) are ______ _________ than those that have serum neutralizing antibodies.

  more susceptible
• Enzootic calf pneumonia (P. multocida)


  unweaned dairy calves
• Shipping fever (M. haemolytica)


  older weanling, stocker, of feeder cattle.
• What is the most common illness among cattle in US feedlots?

  shipping fever
• What is the average incidence rate and mortality rate?

  Incidence: 16.2%

  Mortality: 4%
• T or F: it is a major cause of economic loss in the feedlot and dairy industry

  True
• T or F: it is the largest cause of mortality in feedlots in North America

  True
• What is the incidence rate in post-weaning dairy heifers in the US?

  5.9%
• Most of the infections are


  endogenous
• T or F: it invades the respiratory tract under stress

  True
• What are the important viral infections in predisposing?


  -BVD

  -IBR

  -PI3

  -Bovine RSV
• What is the characteristic shipping fever feature?


  lobar fibronopurulent bronchopneumonia
• Virulence factors of M. haemolytica and P. multocida: Surface proteins and carbs


  -adhesion proteins and fimbrae- allowing adherence to mucosal membranes

  -LPS

  -Lipoproteins
• Virulence factors of M. haemolytica and P. multocida: Toxins and extracellular enzymes


  -leukotoxin of M. haemolytica, which induces apoptosis or cell necrosis in ruminant leukocytes
• Diagnosis includes


  -bacteriology: culture (lung, bronchial lymph node)

  -histology: formalin fixed lung
• Prevention should focus on


  reducing the stressors that contribute to development of the disease
• Other prevention measures


  -cattle should be assembled rapidly into groups

  -new animals should not be introduces to established groups

  -transport time should be minimized

  -calves should ideally be weaned 2-3 weeks before shipment
• Control measures


  metaphylaxis with long-acting antibiotics such as oxytetracycline has been widely adopted as a control measure given "on arrival" to cattle at high risk
• Metaphylaxis on arrival has been shown to


  significantly reduce morbidity and improve rate of gain and in some cases reduce mortality
• What does on arrival processing usually involve?


  administration of modified live vaccines for viral antigens and for bacterial components of shipping fever pneumonia
• Why can these on arrival vaccines not have adequate time to stimulate immunity?

  because in most cases of pneumonia it occurs during the first 2 weeks after arrival