JPC SYSTEMIC PATHOLOGY

RESPIRATORY SYSTEM

August 2017

P-B04

 

Signalment (JPC #2286508): Grower pig

HISTORY:  One of a herd of several hundred 3 to 6-month-old grower pigs experiencing high mortality. 

HISTOPATHOLOGIC DESCRIPTION:  Lung:  Diffusely, alveoli are filled with many foamy alveolar macrophages, low to moderate numbers of degenerate neutrophils, few lymphocytes, occasional colonies of 2 um coccobacilli, eosinophilic beaded to fibrillar material (fibrin), and pale eosinophilic homogenous material (edema).  Multifocally and frequently centered upon bacterial colonies, leukocytes are degenerate with streamed nuclei (oat cells).  Alveolar septa are frequently necrotic, characterized by loss of architecture and replacement with eosinophilic cellular and karyorrhectic debris.  Diffusely, alveolar septa, interlobular septa, and the pleura are expanded by fibrin, necrotic debris, few inflammatory cells, occasional large colonies of coccobacilli, ectatic lymphatics and increased clear space (edema).  Within bronchioles and bronchi, there is loss of epithelium with replacement by a mat of necrotic debris and fibrin.  The lumina contain sloughed epithelial cells, necrotic debris, fibrin, macrophages and degenerate neutrophils.  Bronchiolar and bronchial walls are expanded by edema, fibrin, necrosis, necrotic leukocytes, macrophages, lymphocytes and plasma cells.   Multifocally, arteries have endothelial cell loss; absence of the internal elastic lamina; expansion of the walls by neutrophils, macrophages, fibrin, edema, and necrotic debris (necrotizing vasculitis) and often contain fibrin thrombi.  Multifocally, there are mats of fibrin adherent to the pleural surface. 

MORPHOLOGIC DIAGNOSIS:  Lung:  Pleuropneumonia, fibrinonecrotic, histiocytic and neutrophilic, subacute, diffuse, severe, with necrotizing vasculitis, fibrin thrombi, and large colonies of coccobacilli, breed unspecified, porcine. 

ETIOLOGIC DIAGNOSIS:  Pulmonary actinobacillosis

CAUSE: Actinobacillus pleuropneumoniae

CAUSE SYNONYMS:  Formerly Haemophilus pleuropneumoniae, Haemophilus parahaemolyticu 

CONDITION: Porcine contagious pleuropneumoni 

SYNONYMS: Porcine actinobacillus pleuropneumoni 

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS: PERACUTE/ACUTE

SUBACUTE/CHRONIC

TYPICAL GROSS FINDINGS:
PERACUTE/ACUTE

SUBACUTE/CHRONIC

TYPICAL LIGHT MICROSCOPIC FINDINGS:
PERACUTE/ACUTE

SUBACUTE/CHRONIC

ULTRASTRUCTURAL FINDINGS:

DIFFERENTIAL DIAGNOSIS:<
Gross

Microscopic

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2 6th ed. St. Louis, MO: Elsevier Limited; 2016:532-533.
  2. Gottschalk M, Taylor DJ. Actinobacillus pleuropneumoniae. In: Straw BE, Zimmerman JJ, D'Allaire S, Taylor DJ, eds. Diseases of Swine. 9th ed. Ames, IA: Blackwell Publishing; 2006:563-576.
  3. Lopez A, Martinson A. Respiratory system, mediastinum and pleurae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. St. Louis, MO: Elsevier; 2017:543-544.
  4. Oh Y, Ha Y, Han K, et al. Expression of leucocyte function-associated antigen-1 and intercellular adhesion molecule-1 in the lungs of pigs infected with Actinobacillus pleuropneumoniae. J Comp Pathol. 2013; 148:259-265.
  5. Ohba T, Shibahara T, Kobayashi H, et al. Multifocal granulomatous hepatitis caused by Actinobacillus pleuropneumoniae serotype 2 in slaughter pigs. J Comp Pathol. 2008; 139:61-66.
  6. Ohba T, Shibahara T, Kobayashi H, et al. Granulomatous lymphadenitis associated with Actinobacillus pleuropneumoniae serotype 2 in slaughter barrows. Can Vet J. 2010; 51:733-737.
  7. Zachary JF. Mechanisms of microbial infections. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. St. Louis, MO: Elsevier; 2017:172-173.


Click the slide to view.



Click on image for diagnostic series.



Back | Home | Contact Us | Links | Help |