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

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