Fact Sheet: Bovine Leukosis Virus

BLV Fast Facts

  • Bovine leukosis is caused by the bovine leukosis virus and is a blood-borne disease

  • The primary sign of clinical disease is tumors in the uterus, abomasum, heart, spinal canal and/or lymph nodes

  • 1996 survey (NAHMS) found 88.5% dairy herds, 43% of dairy cows, 38.7% of beef herds, 10.3% beef cows infected

  • Leading cause of condemnation of carcasses in slaughter facilities

  • Economic losses from clinical disease, loss of salvage value, inability to sell to bull stud companies

  • Persistent infection is diagnosed by blood tests (ELISA, AGID)

  • Clinical illness is diagnosed by evidence of tumors or leukemia

  • Blood-borne disease spread by transferring blood or other body fluids with blood cells from infected to uninfected animals

    • Colostrum and waste milk

    • 10—20 % in utero

    • Equipment used between animals including needles, syringes, OB sleeves, dehorners, tattoo pliers, ear taggers, medicine vials, hoof knives, nose tongs, rectal ultrasound equipment, tail docking equipment, ear notchers, milking equipment

How to keep BLV out of a negative herd

  • Test all incoming and returning cattle

  • Segregate and retest in 45—60 days

  • Manage as positive until BLV status is determined

Measures to control the spread of BLV

Critical to prevent horizontal spread of blood and fluids containing blood cells from infected to uninfected animals

  • Clean and dry single use maternity pens; remove calf from cow ASAP

  • Do not feed colostrum from positive cows

  • If prevalence is high (over 60%) freeze colostrum before use to destroy virus

  • Do not feed waste milk

  • If feasible, manage positive and negative cows as separate groups

  • Single use needles should be used; do not use medicine vials or syringes contaminated with blood

  • Clean and disinfect equipment that is used between animals

  • Use burning-type dehorners rather than cutting dehorners

  • Use new OB sleeve for each cow

  • Do not overcrowd animals (no more than 110% in freestalls)

  • Use artificial insemination

  • Implement an integrated pest management program

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