March 2018

Signalment:  (JPC # 1819609):  Sheep

HISTORY:  Tissue from a sheep.

HISTOPATHOLOGIC DESCRIPTION:  Slide A (H&E):  Lymph node:  Diffusely, nodal architecture is effaced and replaced by an abscess characterized by a large central area of lytic necrosis characterized by abundant eosinophilic cellular and karyorrhectic debris admixed with multifocal aggregates of a deeply basophilic, granular mineral, acicular cholesterol clefts, and occasional large colonies of 1x3 um coccobacilli. This area is bounded by a 1 mm thick capsule of dense fibrous connective tissue populated by numerous numbers of degenerate and viable neutrophils with fewer macrophages, lymphocytes, and plasma cells. Multifocally, capsular vessels are surrounded by aggregates of lymphocytes.

Slide B: 

B&B Tissue (Gram stain):  Multifocally scattered throughout areas of necrosis and extending into the peripheral zone of lymphocytes, plasma cells and neutrophils are numerous gram positive, up to 1x3 um coccobacilli.

MORPHOLOGIC DIAGNOSIS:  Lymph node:  Lymphadenitis, necrosuppurative and caseating, focal extensive, chronic, diffuse, severe, (abscess) with multifocal mineralization and large colonies of gram positive coccobacilli, breed unspecified, ovine.

ETIOLOGIC DIAGNOSIS:  Corynebacterial lymphadenitis

CAUSE:  Corynebacterium pseudotuberculosis (ovis)

CONDITION:  Caseous Lymphadenitis (CLA)



-Toxic cell-wall lipid:  Corynomycolic acid cell wall, which is similar to Mycobacterium tuberculosis, protects from lysosomal enzymes thus allowing survival in the phagolysosome; the lipid is also pyogenic

-Exotoxin (sphingomyelin-specific phospholipase D): Acts on sphingomyelin of erythrocytes and endothelial membranes, causing hemolysis, vascular permeability/pulmonary edema, shock and increased bacterial invasion





Abscessed lymph nodes:

COMPARATIVE PATHOLOGY:  (of Corynebacterium and related bacteria)

Organism                                                            Principal disease

Corynebacterium diptheriae

Diphtheria in humans

C.  renale and C. pilosum

Cystitis in cows

C. cystitidis

Hemorrhagic cystitis and pyelonephritis in cows

C. bovis

Rare cause of mastitis; dermatitis in nude mice

Actinobaculum suis (Eubacterium suis)

Pyelonephritis and cystitis in swine

C. kutscheri

Pseudotuberculosis in rodents

C. ulcerans

Wound infections in many animals

Arcanobacter pyogenes

Suppurative infections in cattle, sheep, goats and swine

Rhodococcus equi

Pyogranulomatous pneumonia, lymphadenitis, osteitis and colitis in foals

C. pseudotuberculosis (ovis)

Ulcerative lymphangitis on fetlocks and pectoral abscesses in horses ( pigeon fever or dryland strangles) and rarely cattle


  1. Anderson DE, Rings DM, Kowalski J. Infection with Corynebacterium pseudotuberculosis in five alpacas. J Am Vet Med Assoc. 2005;227:441-448.
  2. Baird GJ, Fontaine MC. Corynebacterium pseudotuberculosis and its role in ovine caseous lymphadenitis. J Comp Path. 2007;137(4):179-210.
  3. Matos AC, Dias AP, Morais M, et al. Granuloma coinfection with Mycobacterium bovis, Mycobacterium avium paratuberculosis, and Corynebacterium pseudotuberculosis in five hunted red deer (Cervus elaphus) in Portugal. Journal of Wildlife Diseases. 2015;51(3):793-794.
  4. Morales N, Aldridge D, Bahamonde A, et al. Corynebacterium pseudotuberculosis infectious in Patagonia huemul (Hippocamelus bisulcus). Journal of Wildlife Diseases. 2017;53(3):621-624.
  5. Nagel-Alne GE, Valle PS, Krontveit R, Solverod LS. Caprine arthritis encephalitis and caseous lymphadenitis in goats: use of bulk tank milk ELISAs for herd-level surveillance. Veterinary Record. 2015;176(7):173.
  6. Perkins SL, Magdesian KG, Thomas WP, Spier SJ. Pericarditis and pleuritis caused by Corynebacterium pseudotuberculosis in a horse. J Am Vet Med Assoc. 2004;224: 1112,1133-1138.
  7. Reboucas MF, Portela RW, Lima DD, et al. Corynebacterium Pseudotuberculosis secreted antigen-induced specific gamma-interferon production by peripheral blood eukocytes: Potential diagnostic marker for caseous lymphadenitis in sheep and goats. J Vet Diagn Invest. 2011;23:213-220.
  8. Stranahan LW, Plumlee QD, Lawhon SD, Cohen ND, Bryan LK. Rhodococcus equi infections in goats: characterization of virulence plasmids. Vet Pathol. 2017; [Epub ahead of print]: doi: 10.1177/0300985817747327.
  9. Valdivia J, Real F, Acosta F, et al. Interaction of Corynebacterium Pseudotuberculosis with ovine cells in Vitro.Vet Pathol. 2012; 50(2:) 318-323.
  10. Valli VEO, Kiupel M, Bienzle D, Wood RD. The hematopoietic system. In: Maxie MG, ed. Jubb, Kennedy, Palmer"s Pathology of Domestic Animals, Vol 3. 6th ed. St Louis, MO: Mosby Elsevier; 2016:204-208.
  11. Varela-Castro L, Lara-Vergara J, Ortega N, et al. Endemic caseous lymphadenitis in a wild Caprinae population. Veterinary Record. 2017;180(16):405.
  12. Zachary JF. Mechanisms of microbial infections. In: McGavin MD, Zachary J, eds. Pathologic Basis of Veterinary Disease, 6th ed. St. Louis, MO: Mosby Elsevier; 2016:185.




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