Bovine lymphoma is a disease that may be sporadic (occurring spontaneously) or caused by infection with the retrovirus bovine leukemia virus (BLV), which is also referred to as enzootic bovine leukosis. The disease has a high prevalence in the United States, in both dairy and beef herds, but has been eliminated in many European countries, New Zealand, and Australia. Infected animals may or may not be symptomatic. Some animals (approximately 40%) develop a persistent lymphocytosis of large lymphocytes. These animals are likely immunocompromised, may have decreased milk production, and be more likely to be culled from the herd. A minor percentage of cows (approximately 5%) develop lymphoma, with tumors in many organs (also referred to as lymphosarcoma or malignant lymphoma). The disease is horizontally transmitted by blood or other body fluids containing lymphocytes or vertically across the placenta from cow to calf. Disease transmission may occur with natural breeding, biting flies, or during various procedures (vaccinations, reproductive exams, dehorning, etc). Some preventive measures may be effective. Concerns extend beyond that of individual animal health, to economic loss, international trade, and public health. There are steps that can be taken to control the disease and to minimize transmission within herds. Genetic selection may also be used. Vaccination is not currently available.
Links to sections in the MVM:
Overview of Bovine Leukosis
Tumors of the Immune System
Neoplasia of the Spinal Column and Cord
References
Bauermann FC, Ridpath JF, Dargatz DA. Bovine leukemia virus seroprevalence among cattle presented for slaughter in the United States. J Vet Diagn Invest. 2017 Sept;29(5):704-706. doi: 10.1177/1040638717702183
Nishiike M, Kaoka M, Doi T, et al. Development of a preliminary diagnostic measure for bovine leucosis in dairy cows using peripheral white blood cell and lymphocyte counts. J Vet Med Sci. 2016. Aug 1;78(7):1145-51. doi: 10.1292/jvms.16-0022
Polat M, Takeshima S, Aida Y. Epidemiology and genetic diversity of bovine leukemia virus. Virology Journal. 2017 14:209. doi: 10.1186/s12985-017-0876-4
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