JPC SYSTEMIC PATHOLOGY

RESPIRATORY SYSTEM

2017

P-B18

 

SIGNALMENT (JPC #2741839):  Pig

HISTORY:  Unknown

HISTOPATHOLOGIC DESCRIPTION:

Lung:  The pleura is diffusely and moderately expanded (up to 500um) by large aggregates of eosinophilic, beaded, fibrillar material (fibrin) admixed with moderate numbers of degenerate neutrophils, fewer lymphocytes, plasma cells and macrophages, multifocal aggregates of karyorrhectic and cellular debris, and mineral (necrosis), which extends into the subpleural pulmonary parenchyma. Alveolar and intralobular septae are similarly expanded but to a lesser degree (up to 3 times normal).  Multifocally (affecting 40% of the section) alveolar and bronchiolar lumina contain an inflammatory exudate admixed with fibrin and necrotic debris (as described above) that occasionally obscures normal architecture.  Bronchiolar epithelial cells are multifocally necrotic (sloughed, shrunken) and discontinuous, with infiltration of inflammatory cells through the bronchiolar wall and into the subepithelial connective tissue. Bronchial subepithelial connective tissue is similarly, though less severely, affected.

Heart:  Diffusely and moderately expanding the epicardium and extending into the subepicardial myocardium are large aggregates of eosinophilic finely beaded to fibrillar material (fibrin), neutrophils, and fewer lymphocytes, macrophages, and rare eosinophils admixed with small amounts of cellular and karyorrhectic debris (necrosis).  Multifocally, subepicardial cardiac myocytes have pale, swollen, and vacuolated cytoplasm (degeneration) or loss of cross striations, pyknotic nuclei and hypereosinophilic cytoplasm (necrosis). 

MORPHOLOGIC DIAGNOSIS:

  1. Lung: Pleuropneumonia, fibrinosuppurative and necrotizing, subacute, multifocal, moderate, breed unspecified, porcine.
  2. Heart: Epicarditis and subepicardial myocarditis, fibrinosuppurative, necrotizing, and histiocytic, subacute, diffuse, moderate.

ETIOLOGIC DIAGNOSIS:  Pleural, epicardial, and myocardial haemophilosis

CAUSE: Haemophilus parasuis

CONDITION: Glasser’s disease

SYNONYMS: Porcine polyserositis and arthritis

GENERAL DISCUSSION:

PATHOGENESIS: 

VIRULENCE FACTORS

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS: 

A vasculitis that leads to gray-white friable material (fibrin) on serosal surfaces and may also contain a fibrinous exudate and edema

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

3 main rule-outs for polyserositis in pigs are: Haemophilus parasuis, Mycoplasma hyorhinis, and Streptococcus suis type II

COMPARATIVE PATHOLOGY:

Haemophilus parasuis, but not Glasser’s disease, has been reported in the wild boar

Causes of polyserositis in other species:

Causes of polyarthritis

References:

  1. Cuesta-Gerveno JM, Perez, DR, Blanco PG, et al. Fatal infection due to Haemophilus parasuis in a young wild boar (Sus scrofa).  J Vet Diagn Invest. 2013;25(2):297-300.    
  2. Boulianne M (ed), Avian Disease Manual, 7th 2013: 44.
  3. Craig LE, Dittmer KE, Thompson K. Bones and joints. In: Maxie MG, ed.  Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. St Louis, MO: Elsevier; 2016:151-2. 
  4. Zachary JF. Mechanisms of microbial infection. In: Zachary JF. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 174-175.
  5. Zachary Jf.  Respiratory system, mediastinum, and pleurae. In: Zachary JF. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 544


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