Central Nervous System Lymphoma in Cows

Central nervous system lymphoma in cows is a cancer of lymphoid cells that affects the brain, spinal cord, or tissues around them. In cattle, lymphoma is the most common tumor that spreads to the nervous system, and it is often associated with bovine leukemia virus (BLV). The spinal cord is affected more often than the brain, so many cows first show trouble standing, weakness in the hind limbs, or progressive paralysis.

This condition is serious because the nervous system does not have much room for swelling or tumor growth. Even a small mass can compress the spinal cord and cause major changes in movement, posture, and comfort. Signs may look like trauma, listeriosis, rabies, spinal abscess, or metabolic disease at first, so a prompt exam matters.

For many cattle, especially adults, CNS lymphoma is part of a wider lymphosarcoma process rather than an isolated brain or spinal problem. Your vet may also look for enlarged lymph nodes, weight loss, reduced production, or tumors in other organs. In some cases, the diagnosis is strongly suspected while the cow is alive but confirmed only after necropsy.

In adult cattle, central nervous system lymphoma is most often associated with bovine leukemia virus. BLV is a blood-borne retrovirus that infects lymphocytes. Most infected cattle never develop tumors, but a small percentage later develop malignant lymphoma, usually in adulthood. When lymphoma involves or spreads to the spinal canal or brain, neurologic signs can follow.

Not every case is caused by BLV. Cattle can also develop sporadic forms of lymphosarcoma that are not linked to BLV. These forms are classically described in younger animals, including juvenile, thymic, and cutaneous presentations, although nervous system involvement is less typical than with adult multicentric disease.

BLV spreads mainly when infected white blood cells are transferred between cattle. Risk points include reused needles, contaminated dehorning or tattoo equipment, rectal sleeves used on multiple animals, blood transfer during procedures, and possibly biting flies. That means the cancer itself is not contagious, but the virus that raises risk for some forms of lymphoma can spread within a herd.

A diagnosis of CNS lymphoma does not mean every neurologic cow on a farm has BLV-related cancer. Trauma, listeriosis, spinal abscesses, toxicities, metabolic disease, and other neurologic disorders can look similar. Your vet will sort through those possibilities before drawing conclusions.

Diagnosis starts with a careful farm call exam. Your vet will look at gait, limb placement, strength, spinal reflexes, cranial nerve function, mentation, and whether the problem fits the brain, spinal cord, or peripheral nerves. They will also review age, production stage, herd BLV status, recent injuries, and whether other cattle are affected.

Basic testing may include a complete blood count, serum chemistry, and BLV testing with ELISA, AGID, or PCR depending on the situation and lab access. These tests can support suspicion, but they do not prove that a neurologic cow has CNS lymphoma. Some affected cattle have lymphocytosis or other evidence of leukosis, while others do not.

If practical, your vet may discuss cerebrospinal fluid collection, ultrasound of accessible masses, fine-needle aspirates of enlarged lymph nodes, or referral-level imaging. In cattle, advanced imaging is often limited by size, transport stress, availability, and cost range. Because of that, many cases are diagnosed as presumptive antemortem and confirmed later with necropsy and histopathology.

Necropsy can be especially valuable for herd planning. It may confirm lymphoma in the spinal canal, epidural space, vertebral canal, or brain, and it can help rule out infectious or toxic causes of neurologic disease. That information can guide BLV testing, biosecurity changes, and future culling or segregation decisions with your vet.

You cannot fully prevent every case of lymphoma in cattle, but you can reduce risk from BLV-associated disease by limiting virus spread within the herd. Prevention focuses on blood-control biosecurity. That includes never reusing needles, disinfecting or changing equipment between animals, using clean rectal sleeves for each cow, and choosing bloodless or lower-blood procedures when possible.

Herd testing is another useful tool. Your vet may recommend screening with milk or serum ELISA, then making a plan based on prevalence, production goals, and replacement strategy. Some farms cull positives aggressively, while others separate positive and negative groups and focus on reducing transmission pressure over time. There is currently no vaccine for BLV.

Good fly control, careful handling, and testing incoming animals can also help. If you buy cattle, ask about BLV status and quarantine protocols. A confirmed case of lymphoma in one cow does not always mean a herd crisis, but it is a good reason to review biosecurity and testing with your vet.

Because CNS lymphoma is often detected late, prevention is usually about herd management rather than catching a single case early. Prompt evaluation of weak or ataxic cattle still matters. It protects welfare, helps rule out contagious neurologic disease, and may uncover BLV-related problems that affect longer-term herd health decisions.