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Acute Lymphoblastic Leukemia in Dogs

Acute lymphoblastic leukemia is a disease in which cancerous lymphoblasts (cells that are in the beginning stage of development) and prolymphocytes (cells in the intermediate stage of development) reproduce, and then circulate through the bloodstream, entering into the body's organs. These cells will also infiltrate both the inside of the bone marrow and the outside (extramedullary) of the bone marrow, displacing hematopoietic stem cells.

Hematopoietic cells are the normal, healthy precursors of red blood cells, lymphocytes, erythrocytes, platelets, eosinophils, neutrophils, macrophages and mast cells. Dogs with this disease will acquire impaired immunity, and will be inclined to contracting infections.

Symptoms and Types

• Generalized illness, no specific symptoms
• Tiny, non-raised purple spots on the skin, from hemorrhages beneath the skin (petechia), or dark red-purple spots on the gums, from ruptured blood vessels under the skin (ecchymotic)
• Inconstant symptoms, dependent upon which organs have been infiltrated by neoplastic (abnormal) cells

Causes

• Suspected but unproven causes in dogs:
  • Ionizing radiation
  • Cancer-causing viruses
  • Chemical agents

Diagnosis

You will need to give your veterinarian a thorough history of your dog's health and onset of symptoms. Your veterinarian will perform a thorough physical exam on your dog, taking into account the background medical history, and possible incidents that might have precipitated this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. If cancer is suspected, your doctor will also need to take bone marrow biopsies (samples) for a microscopic (cytologic) examination of the cells. If malignant cancer cells are present, the examination will show lymphoblastic infiltration of the bone marrow. Abdominal x-rays may also be taken to check for an enlarged liver and/or an enlarged spleen.