Well-differentiated lymphocytic leukemia in a dog: long-term survival without therapy

Well-differentiated lymphocytic leukemia was found during routine hematologic examination of a 12-year-old female poodle with signs of anxiousness, panting and pica. The total white blood cell count was 106,900/microliters and at least 90% of the leukocytes were small, normal-appearing lymphocytes. The dog was examined several times during a 23-month period before it was killed at the owner's request for conditions unrelated to the leukemia. The hematologic picture of the leukemia was essentially unchanged during this time. A deep nuclear cleft was seen in most lymphocytes examined by electron microscopy. Cell surface markers showed most blood lymphocytes to be B-cells. These cells responded poorly to mitogen stimulation.