JPC SYSTEMIC PATHOLOGY

DIGESTIVE SYSTEM

October 2024

D-T01

 

Signalment (JPC #1617774): A pig

 

HISTORY: This animal was non-confinement raised and died acutely.

 

HISTOPATHOLOGIC DESCRIPTION: Liver: Affecting 60% of hepatic lobules, there is submassive necrosis characterized by disorganization and loss of centrilobular and midzonal hepatic cords with replacement by abundant necrotic debris and hemorrhage. Remaining hepatocytes are individualized, shrunken, and hypereosinophilic with pyknotic, karyorrhectic, or karyolytic nuclei (single cell death), and are admixed with moderate hemorrhage, fibrin, edema, and few neutrophils. Adjacent to areas of necrosis, few hepatocytes are swollen with clear, vacuolated cytoplasm (degeneration) admixed with few lymphocytes, plasma cells, rare neutrophils, and eosinophils. Centrilobular sinusoids are diffusely markedly congested. Multifocally within portal areas, there is a mild to moderate infiltrate of the previously described inflammatory cells, expansion by eosinophilic homogenous fluid (edema), increased numbers of ductular profiles (ductular reaction) and mildly dilated lymphatics.

 

MORPHOLOGIC DIAGNOSIS: 1. Liver: Necrosis, acute, centrilobular to midzonal (submassive), diffuse, with multifocal hemorrhage and congestion, breed unspecified, porcine.

2. Liver: Hepatitis, portal, lymphoplasmacytic, chronic , multifocal, mild. 

 

ETIOLOGIC DIAGNOSIS: Toxic hepatic necrosis

 

CAUSE: Xanthium strumarium 

 

CONDITION: Cocklebur intoxication

 

GENERAL DISCUSSION:

• Xanthium spp. from the Asteraceae family; cause fatal hepatic necrosis most often in pigs and less commonly in cattle and sheep 
• The toxin is carboxyatractyloside, a diterpenoid glycoside which targets the liver, especially the centrilobular hepatocytes
• Other diterpenoid glycosides include: other atractylosides, parquin, carboxyparquin and wedeloside
• X. strumarium is the most common species; there are three varieties with worldwide distribution (X. pungens in Australia and X. cavanillesii in Brazil and South Africa)
• Toxin concentration is highest in the seeds and cotyledon (seedling stage), which is when the plant is most palatable 

 

PATHOGENESIS:

 

TYPICAL CLINICAL FINDINGS:

• Clinical signs appear abruptly within hours of ingestion
• Depression, nausea, weakness, ataxia, anorexia, hypersensitivity, opisthotonos, convulsions, acute death
• Swine: Ascites

  

TYPICAL GROSS FINDINGS:

• Accentuated hepatic centrilobular pattern and submassive necrosis 
• Ascites with fibrin strands on hepatic and visceral surfaces
• May have burs in stomach, rumen

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

 

DIFFERENTIAL DIAGNOSIS 

Microscopic:

• Iron toxicity (iron dextran): Usually neonatal swine; centrilobular to massive hepatic necrosis; can cause iron-catalyzed lipid peroxidation in hepatocytes and skeletal muscle
• Vitamin E/selenium deficiency (hepatosis dietetica, D-M10): Massive, multifocal hepatic necrosis and stromal collapse; cardiomyocyte degeneration and necrosis; fibrinoid necrosis of arterioles; steatitis
• Gossypol toxicosis (cottonseed, D-T02): Submassive hepatic necrosis; mid-zonal fatty change; also myocardial degeneration and necrosis
• Cresol toxicosis (coal-tar pitch/clay pigeon): Centrilobular to massive hepatic necrosis, with jaundice and ascites 

 

COMPARATIVE PATHOLOGY:

Toxic plant causes of centrilobular necrosis in animals: 

 

Table adapted from Pathologic Basis of Veterinary Disease, 7^th ed., 2022, E Table 8-1 Common Hepatotoxic Plants of Veterinary Importance

 

REFERENCES:

1. Brown DL, Van Wettere AJV, Cullen JM. Hepatobiliary system and exocrine pancreas. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022: ETable 8-1: 512. 
2. Cullen JM, Stalker MJ. Liver and biliary system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier Ltd; 2016: 330- 331.
3. Ensley SM, Radke SL. Toxic Minerals, Chemicals, Plants and Gases. In: Zimmerman JJ, Karriker LA, Ramirez A, Schwartz KJ, Stevenson GW, Zhang J Diseases of Swine. 11^th ed. Hoboken, NJ: Wiley Blackwell; 2019: 1080. 

 

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