Difference between revisions of "Respiratory Bacterial Infections - Pathology"

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===Contagious bovine pleuropneumonia (CBPP)===
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===[[Contagious Bovine Pleuropneumonia]] ===
[[Image:Contagious bovine pleuropneumonia.jpg|right|thumb|100px|<small><center>Contagious bovine pleuropneumonia (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*Caused by [[Mycoplasma mycoides subsp. mycoides|''Mycoplasma mycoides'']], small colony variant
 
*Causes a fibrinonecrotic [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|pneumonia]] and [[Pleural Cavity & Membranes Inflammatory - Pathology|fibrinous pleuritis]]
 
*Also affects caudodorsal areas
 
*[[Lungs Inflammatory - Pathology#Bronchopneumonia|Bronchopneumonia]] -> [[Lungs Inflammatory - Pathology#Lobar pneumonia|lobar pneumonia]]
 
*Sequestra are common
 
*NB: similarity to pneumonic pasteurellosis but CBPP has more pronounced marbled effect
 
*Interstitial septa are markedly widened by fibrinous exudate and the necrotic areas may have a fibrous capsule
 
*Large colony variant will cause a similar disease in goats
 
  
 
===Enzootic pneumonia of calves===
 
===Enzootic pneumonia of calves===

Revision as of 14:05, 30 June 2010


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()Map CARDIORESPIRATORY SYSTEM (Map)
RESPIRATORY SYSTEM INFLAMMATION



In general

  • Main clinical expression is as secondary invaders of previously damaged lung tissue due to viral or parasitic involvement or environmental stress
  • Some are initial pathogens in their own right while others can damage the tract allowing invasion by more pathogenic types

In Dogs

Infectious Canine Tracheitis

Tuberculosis - Dogs

Nocardiosis

In Cats

Chlamydiosis, Feline

Mycoplasma felis

In Horses

Strangles

Streptococcus equi subsp. zooepidemicus

Glanders

Rhodococcus equi

In Cattle

Necrotic Laryngitis

Cillia-associated Respiratory Bacillus

Pneumonic Pasteurellosis

Tuberculosis - Cattle

Contagious Bovine Pleuropneumonia

Enzootic pneumonia of calves

Acute suppurative pneumonia (Image sourced from Bristol Biomed Image Archive with permission)
Calf pneumonia - chronic, with abscesses, fibrosis (Image sourced from Bristol Biomed Image Archive with permission)
  • Range of infectious agents together with managemental and environmental stress cause damage to the respiratory tract
  • Causes unthriftiness in animals < 6 months old
  • Usually the primary pathogen is a virus, secondary pathogens are bacteria and mycoplasmas
  • Pathogens:
  • All transmitted by aerosol and direct contact
  • Gross pathology:
    • Consolidation of the cranioventral areas which increases in volume with duration
    • On cut surface, exudate in the main airway of affected lobules with thickening of the surrounding connective tissue
  • Micro pathology:
    • Substantial lymphoid tissue around the airways
    • Even to proper follicle formation, some of which may be large enough to compress the lumen
    • Mixed cell exudate in the airway lumen
    • Partial alveolar collapse distal to the compression
    • Alveolar exudate contains a mixture of inflammatory cells
    • Slight thickening of the alveolar walls with lymphocytes

Acute exudative pneumonia

In Sheep

Laryngeal chondritis

Oedema and chondritis in larynx of sheep (Image sourced from Bristol Biomed Image Archive with permission)

CAR bacillus

Enzootic pneumonia of lambs

  • Caused by Pasteurella (Manheimia) haemolytica, possibly together with Mycoplasma ovipneumoniae
  • Mainly in late spring/early summer after environmental stress i.e. handling or moving
  • May be acute with producing a fibrinonecrotic bronchopneumonia and associated pleuritis
  • Or tending towards chronicity with abscessation and fibrous pleural adhesions
  • A septicaemic form (mortality 5%) is reported to follow the stress of movement to new pasture in the autumn in weaned lambs.
  • Foci of necrosis containing many bacteria are seen at the site of initial invasion in the pharynx and in the liver
  • Meningitis in young lambs and mastitis in ewes are other expressions

Melioidosis (Pseudoglanders)

  • Caused by Pseudomonas (Malleomyces) pseudomallei, Closely related to P. mallei in horses
  • Causes disease in sheep, goats and pigs, occasionally other species
  • Starts as a pyemia and localises in varius tissues, including the lung as abscessation
    • Encapsulated abscesses contain yellow, caseous or creamy pus
  • Pneumonia and arthritis are the most common presentation

In Pigs

Atrophic Rhinitis

Severe atrophic rhinitis (Image sourced from Bristol Biomed Image Archive with permission)
  • Atrophy of nasal turbinates and distortion and shortening of the snout
  • Caused by co-infection of the nasal mucosa with
    • Bordetella bronchiseptica
      • Appears to facilitate colonisation of nasal epithelium by the toxigenic Pasteurella
    • Toxin-producing strain of Pasteurella multocida capsular type D (or sometimes A)
      • Experimental evidence shows that the toxin acts directly on bone cells of the nasal turbinates to cause bone loss, each pathogen can cause atrophy itself but greater damage when together
  • Exacerbated by adverse dietary and managemental factors
  • In rapidly growing young pigs (4-12 weeks old)
  • Clinical signs
    • Progressive facial deformity with rhinitis, catarrhal nasal discharge
    • Sneezing, coughing, can progress to dyspnoea and anorexia
  • Gross pathology
    • Overlying skin on shortened snout is thrown into folds
    • Deviation of the snout to most affected side
    • Various loss of turbinate bone, ventral usually more affected
    • Deviation of nasal septum away from affected chamber
    • Inflammatory, haemorrhagic and ulcerative lesions in the nasal mucosa
  • Micro pathology
    • Reduction in the amount of bone in the turbinates
    • No osteoid laid down between osteoblasts and existing bone
    • Increased fibrous tissue
    • Non-specific mucosal inflammation
  • 2 forms of the disease
    • 'Progressive' atrophic rhinitis
      • Due to infection of the nasal turbinates by P.multocida strains carrying the toxA gene that encodes for an osteolytic toxin. P.multocida adheres poorly to mucous membranes, and therefore requires a predisposing nasal insult to assist colonisation eg: co-infection with B.bronchiseptica or Porcine cytomegalovirus (inclusion body rhinitis)
      • Turbinate bone atrophy is permanent and progressive
    • 'Non-progressive' atrophic rhinitis
      • Due to infection of the nasal turbinates by Bordetella bronchiseptica strains alone, that carry a gene that encodes for a dermonecrotic toxin.
      • Turbinate bone can regenerate by the time of slaughter

Necrotic laryngitis in pigs

Enzootic pneumonia of pigs

Enzootic pneumonia of pigs(Image sourced from Bristol Biomed Image Archive with permission)
  • Caused by Mycoplasma hyopneumoniae and Mycoplasma hyorhinis
  • Also called mycoplasmal pneumonia
  • Major cause of unthriftiness in young pigs
  • Pneumonia in weaned pigs
  • Cough, reduced growth rate
  • Attached to cilia - no mucociliary clearance
  • Usually non-fatal unless there is secondary infection (e.g. Pasteurella multocida)
  • Gross pathology:
    • Confluent consolidation of the cranioventral lung lobes
    • In other areas there may be small red to grey focal lesions evident which indicate the bronchiolar orientation of the inflammatory process
  • Histologically
    • Changes result from a catarrhal bronchointerstitial pneumonia
    • In chronic cases, prominent accumulations of lymphoid cells can be seen around airways and blood vessels

Actinobacillus pleuropneumoniae

Pasteurellosis in pigs

Contagious porcine pleuropneumonia

  • Caused by Haemophilus (Actinobacillus) pleuropneumonia
  • Seen mainly between 6wks-6mths of age but will affect any age
  • Highly pathogenic strains are capable of initiating disease on their own with high mortality in young pigs
  • A fibrinonecrotic bronchopneumonia with pleurisy
  • Foci of haemorrhagic consolidation or necrosis, mainly around major bronchi, tend to sequestrate
  • Tending to spread throughout all lung lobes: therefore a cranioventral distribution may not be particularly evident

Glasser's disease

Streptococcal pneumonia

Tuberculosis in pigs

  • Pigs are susceptible to the Mycobacterium spp. causing tuberculosis in cattle
  • Rarely extends to lungs after haematogenous spread from ingested bacteria causing tubercles with various degrees of calcification, encapsulation and caseation

In Rabbits

Snuffles

CAR bacillus