Dog Lymph Node Biopsy

Lili Duda, VMD
Last Modified: November 1, 2001

Dear OncoLink "Ask the Experts,"
My 12-year-old dog is currently being tested for Lymphosarcoma. The lymph nodes are swollen from her throat to the back of her legs. Aspirates were taken a week ago and the pathology came back that there are cells indicative of cancer in the lymph nodes but they aren't actually able to determine which type. She went in Friday to have pieces of her lymph nodes removed for biopsy, and when my vet cut the casing over the first lymph node, he said pus "flew" out of it. He then decided to biopsy a second one and the same thing happened. He said he's biopsied hundreds of lymph nodes and has never seen this. She was first put on antibiotics, which didn't take the swelling down. She's now on Baytril and still no sign of the lymph nodes decreasing in size. Is pus in the lymph nodes indicative of any of type of Lymphoma?

Lili Duda, VMD, Editor of the OncoLink Veterinary Oncology Section, responds:

First, regardless of whether your dog's lymph nodes are enlarged due to infection/inflammation or cancer, the biopsy should give you a definitive diagnosis. Second, although the material coming from the lymph node looked like pus, it might actually be malignant lymphoid tissue. When a lymph node is full of malignant lymphoid cells, it can bulge when cut open, and the tissue can look "creamy" or pus-like. I would recommend a consultation with a board-certified veterinary oncologist. If your dog needs treatment quickly, and the definitive biopsy results are not back yet, an oncologist will sometimes give a relatively safe lymphoma drug called L-asparaginase on the presumption that the enlargement is due to lymphoma, and see if the lymph nodes respond. This is similar to giving antibiotics on the presumption that the lymph nodes are enlarged due to infection. However, as mentioned earlier, the biopsy should give you an answer, and should not take more than 3-5 working days to get the results. Good luck in the care of your dog.

From the National Cancer Institute