Multicentric lymphoma in dogs.

What it is

Lymphoma is cancer of the lymphocytes — a type of white blood cell. "Multicentric" means it shows up in multiple lymph nodes throughout the body, the most common presentation in dogs (other forms include alimentary, mediastinal, and cutaneous).

Lymphomas are further classified as B-cell or T-cell based on the lymphocyte type, and as low-grade (indolent) or high-grade (aggressive) by appearance under the microscope. These distinctions matter a lot for prognosis and treatment plan.

Signs to watch for

• Firm, painless swellings in the lymph nodes — most easily felt under the jaw, in front of the shoulders, and behind the knees.
• Lethargy or reduced appetite — sometimes subtle, especially early on.
• Weight loss over weeks despite eating normally.
• Increased thirst and urination in some cases — particularly if calcium levels rise (often associated with T-cell forms).

Lymphoma is often caught when an owner notices the swollen nodes during a casual pet, or when a vet finds them on a routine exam. Many dogs feel and act normal at first diagnosis.

How veterinarians diagnose it

Diagnosis typically starts with a fine-needle aspirate of an enlarged lymph node — your vet inserts a small needle, draws cells, and a clinical pathologist examines them. This is often enough to confirm lymphoma.

Additional testing usually follows: bloodwork (CBC + chemistry), urinalysis, chest and abdominal imaging (radiographs or ultrasound), and flow cytometry or PARR testing on the aspirate to determine B-cell versus T-cell and clonality. This staging defines the disease and helps the oncologist tailor treatment.

In some cases, a biopsy of a whole lymph node (excisional biopsy) is performed for histologic grading, which is important for prognosis.

What treatment usually looks like

Lymphoma is one of the most chemotherapy-responsive cancers in dogs. Most dogs tolerate canine chemotherapy substantially better than humans do — typically without significant hair loss or prolonged nausea.

• CHOP-based multi-agent protocols are standard-of-care for high-grade B-cell multicentric lymphoma. These combine several chemotherapy drugs over several months.
• Single-agent protocols (such as single-agent doxorubicin) are an alternative for owners who prefer less intensive treatment.
• Prednisone alone can produce short-term responses but is generally considered palliative.
• Rescue protocols exist for dogs who relapse after initial treatment.
• Newer therapies — including monoclonal antibodies and personalized vaccines — are active areas of clinical research.

T-cell lymphoma generally responds less well to standard CHOP and may benefit from different protocols. Your oncologist will tailor the recommendation to your dog's specific subtype.

Prognosis

Multi-agent CHOP-style protocols for high-grade B-cell multicentric lymphoma typically produce remission in a large majority of dogs, often within weeks of starting treatment. Reported median survival times in the veterinary oncology literature for B-cell disease treated with CHOP fall roughly in the 12-month range, with substantial individual variation.

T-cell forms generally have shorter median survival on standard protocols. Indolent (low-grade) lymphomas often progress slowly over years.

"Median" means half of dogs lived longer, half shorter — your dog's path may differ. Your veterinary oncologist can frame these numbers around your case.

Questions to ask your vet

• What is the specific subtype — B-cell or T-cell, high-grade or indolent?
• Has my dog been staged? What did imaging and bloodwork show?
• What protocols are realistic for our situation, including financial considerations?
• What does the treatment schedule look like week by week?
• What side effects should I expect and what would prompt a call?
• Are there clinical trials open for my dog's specific subtype?
• What's the plan if the disease comes back after initial response?

Where to learn more

The Veterinary Cancer Society and the American College of Veterinary Internal Medicine (ACVIM) publish consensus and overview materials accessible to owners. Most US vet-school teaching hospitals maintain owner fact sheets on lymphoma. PubMed indexes the primary literature for the curious.

For clinical trials enrolling dogs with lymphoma, see the SciRouter Vet trial finder.