Enzootic bovine leukosis

Veterinary advice should be sought before applying any treatment or vaccine.

Enzootic Bovine Leukosis

Enzootic bovine leukosis (EBL) is a significant disease of cattle worldwide, characterized by the development of tumors on lymphatic tissues (lymphosarcoma) throughout the body, such as the spleen, thymus and lymph nodes. It is caused by bovine leukemia virus (BLV), a malignant B cell lymphoma. Clinical signs of EBL vary depending on the location of where tumors develop and the severity and stage of progression.

Less than 1% of cows infected with BLV develop lymphosarcoma, and one-third of cattle infected with BLV develop persistent lymphocytosis.

BLV is transmitted to cows through blood transfer, through the placenta during pregnancy and by consumption of colostrum or milk from BLV-infected cattle.


Enlarged lymph nodes
Reduced feed intake
Weight loss
Decreased milk production
Reluctance to move or rise
Protruding eye


  • History
  • Clinical signs
  • Physical exam
  • real-time PCR
  • Serologic testing


Supportive care


  • Reducing insect populations
  • Use individual sterile needles for transdermal injection or blood collection.
  • Disinfect tattoo equipment between animals.
  • Use milk replacer to feed preweaned calves.
  • Use BLV-seronegative recipients for embryo transfer.
  • Wash and rinse instruments in warm water, then submerge in an appropriate disinfectant.
  • Heat-treat or pasteurize colostrum
  • Use electric dehorners, or disinfect dehorning equipment between animals.
  • Replace examination gloves and sleeves between animals.

Article Reference

Risk Factors

  • Using the same needles, syringes, and vaccinations between cattle
  • The use of dehorning equipment with a gouge or saw
  • Tattooing
  • Using blood-contaminated surgical equipment
  • Injured herd members with bleeding wounds } Abundant insect populations


  • Bovine leukemia virus (BLV)

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