Bovine leukemia virus (BLV) is widespread in dairy cattle populations, with most infected animals remaining clinically normal but a proportion developing lymphoma causing significant welfare harm.
BLV lymphoma causes progressive suffering as tumors develop in multiple organ systems. Depending on tumor location, cattle may experience esophageal obstruction causing bloat, cardiac involvement causing exercise intolerance, spinal cord compression causing hindlimb paralysis, or lymph node enlargement causing various regional signs. The progressive nature of lymphoma means affected animals experience escalating welfare compromise without effective treatment. Early identification of lymphoma and humane euthanasia before severe suffering occurs is the welfare-protective management approach. BLV control programs through testing and culling reduce the pool of infected cattle from which lymphoma cases arise.