Leukemia In Dogs – Symptoms, Causes, And Treatments

Leukemias are progressive, malignancy of hematopoietic progenitors that results in myelophthisis causing extramedullary hematopoiesis and the consequent incursion of peripheral tissues.

Hematopoietic malignancies are a complex group of disorders that includes leukemias which are a malignant transformation of hematopoietic progenitors in blood-forming organs, characterized by abnormal production of leukocytes and their precursors.

Canine leukemia accounts for 10% of all blood cancers diagnosed. Dog’s immune system produces excess cancerous white blood cells called lymphocytes, at the expense of other essential blood cells. This abnormal expansion in number is due to certain stimuli that inflame the immune system to activate production.

Leukemia can also be considered as “lymphoma of the blood”. There are different types of leukemia that have been reported, the most common forms are acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL). Both forms may mimic other common diseases, such as chronic ehrlichiosis or lymphoma.

Acute lymphoblastic leukemia accounts for 35-40% of all leukemias in dogs. The acute type is aggressive in nature and spreads quickly.

Chronic lymphocytic leukemia accounts for 25-40% of leukemias in dogs. CLL doesn’t appear as aggressive or spread as quickly as the acute type.

Acute lymphoblastic leukemia

• Pale skin
• Loss of appetite/ loss of weight
• Lethargy and weakness
• Repeated infections over a short time.
• Bruising (may not be easily seen)/ Bleeding
• Diarrhea/Vomiting
• Change in activity level
• Polyuria/ polydipsia
• Fever
• Lameness
• Swollen lymph nodes

Chronic lymphocytic leukemia

• Painless swelling of the lymph nodes in the underarm, neck, groin or stomach.
• Lethargy/weakness
• Easy bruising or bleeding
• Fever and infection.
• Loss of appetite
• Mild anemia
• Enlarged spleen

Survival rate and prognosis are dependent on the grade and stage of cancer, and how promptly treatment is given.

Acute Leukemia Treatment

• More likely to be aggressive than chronic leukemia, Acute leukemia requires immediate and appropriate care.
• Aggressive therapy and supportive care
• Supportive care includes blood transfusions (for anemic dogs), intravenous fluids, antibiotics, and feeding tubes for dogs that cannot eat on their own.
• A chemotherapeutic protocol involving Chemotherapy induction agents will be initiated- vincristine, cyclophosphamide, prednisone, doxorubicin, and L-asparaginase.
• For non-responsive dogs, other chemotherapeutics such as cytosine arabinoside or cyclophosphamide will be added

Chronic Leukemia Treatment

Careful monitoring, supportive care in-home, and record any new symptoms.

As the condition progresses gradually, no aggressive treatment in the beginning stages may be required.

However, regular vet checks and blood work to monitor blood cell counts are mandatory

Chemotherapy— Involves a combination of prednisone and chlorambucil administered via either a continuous or pulse therapy protocol

Pulse therapy protocol - Chlorambucil (15-20 mg/m2 PO/ alternate week) + for refractory cases, prednisone (50 mg/m2 PO once daily for 1 week), then alternate days from the second week.

Continuous therapy protocol:Chlorambucil (6 mg/m2 PO once daily for 1-2 weeks initially, tapering to 3 mg/m2 daily after 14 days), with concurrent prednisone (30 mg/m2 PO/ first week) with doses reduced to 20 mg/m2 PO daily (second week) and then, third week onwards- 10 mg/m2 PO/ alternate days

Refractory cases of CLL – Cyclophosphamide

Weekly once (200 mg/m2 IV once) or 4 days per week (50 mg/m2 PO)

Leukemia is irreversible without medical management and doesn’t cure on its own that is why vets emphasize medical intervention.

Prevention is not possible for leukemia as the causes of leukemia in dogs is varied.

Treatment and survival rates vary depending on the grade and stage of cancer.

Good overall health and early detection are the only ways to prevent Leukemia.

Check your dog on a regular basis and consult your veterinarian immediately if you find any odd lumps or lesions.

Bulldog, Cocker Spaniel, Jack Russel Terrier, Dachshund, Golden Retriever, German Shepherd, Boxer, Labrador Retriever, English Setter, Middle Age Dogs, Senior Dogs

1. Causes

• Mutation in the bone marrow
• Radiation exposure
• Certain viral infections (Retroviruses)
• Exposure to carcinogens or toxic chemicals (benzene and phenylbutazone).

2. Types:

Acute lymphocytic leukemia (ALL)

• A more potent version of leukemia
• Prevalent in younger dogs, and male dogs (3:2 male: female ratio reported)
• The median age of diagnosis is 6 years old
• This is characterized by a higher presence of lymphoblasts (immature lymphocytes) in peripheral blood

Chronic lymphocytic leukemia (CLL):

• Much less aggressive than the acute type
• The average age of dogs with CLL is approximately 10 to 12 years.
• The most common abnormality is leukocytosis due to mild to marked lymphocytosis.
• Anemia is quite common, affecting approximately 80% of dogs
• There are two types of CLL
  1. Chronic lymphocytic leukemia – this type is more common and originates in lymphocytes
  2. Chronic myeloid leukemia (chronic myelogenous leukemia)- myeloid cells, or non-lymphocytic white blood cells

3. Morbidity:

Stages:

Stage 0: lymphocytosis only (low risk- longer survival rates)

Stage I: lymphocytosis + lymphadenopathy (medium risk)

Stage II: lymphocytosis + hepatomegaly and/or splenomegaly (intermediate risk)

Stage III: lymphocytosis + anemia with/without splenomegaly, hepatomegaly or lymphadenopathy (high risk)

Stage IV: lymphocytosis + thrombocytopenia with/without splenomegaly, hepatomegaly or lymphadenopathy (highest risk)

Binet stages - Clinical stages of leukemia

This is based on a number of areas of lymphoid tissues affected.

• Clinical stage A: swollen Lymph nodes - cancer is limited to fewer than three areas.
• Clinical stage B: cancer is in more than three areas, and lymphoid tissues are swollen.
• Clinical stage C: advanced stage, anemia and/ or thrombocytopenia

4. Mortality:

• Acute lymphocytic leukemia:Untreated dogs could die within weeks.
• Chronic lymphocytic leukemia (CLL): The median survival time is around 12 months. This gets lesser for older dogs. After initiation of treatment, only 30 percent of dogs survive beyond 2 years.

5. Diagnosis:

• Routine hematology, blood smears
• Bone marrow aspirations and core biopsies
• Immunophenotyping
• Clonality assessment by polymerase chain reaction (PCR) testing
• Abdominal ultrasound

6. Prognosis:

Leukemia's activity is complicated and depends on many factors. In general, the cancer is staged from I-IV; stage, I is less destructive than stage IV leukemias.

Typically, the prognosis is less favorable if:

• The dog is the susceptible breed category
• Older dogs
• Having other blood disorders

Grade I leukemia’s can have a good prognosis: surgery and conventional radiation therapy

Stage II dogs can still have a good prognosis after treatment including surgery, radiation, and chemotherapy. Expected Survival times are over 18 months.

Stage III and IV dogs have a guarded prognosis^{. The expected} survival time is only weeks, even with surgery and chemotherapy

Contact your vet right away, if you notice any of the following:

• Repeated infections over a short time.
• Bruising (may not be easily seen) / Bleeding
• Polyuria/ polydipsia

Nutritional management for Leukemia: Diet high in protein, high fat, and low in carbohydrates

• Low fat, high protein foods- White-Fleshed Fish, Skinless, White-Meat Poultry, Beans, Peas, and Lentils
• Protein- chicken breasts, turkey breasts, liver, ½ Cup Raw Salmon (or cooked)
• Lean meats, such as chicken breast, sirloin, or pork
• DHA-mackerel, salmon, herring, sardines, and caviar
• Antioxidants- Blueberries, blackberries, Steamed broccoli, spinach, cooked yellow squash, kale, and green beans
• Fats- Chicken/turkey fat or beef tallow

As with any cancer, proper and earlier diagnosis, as well as aggressive treatments, gives more successful outcomes.

Dogs with chronic leukemia often survive for up to 18 months or some, more than 2 years without chemotherapy, but with treatment, the prognosis is even better.

Acute stage I leukemia can have a good prognosis: Surgery and conventional chemotherapy. Advanced acute leukemias exhibit erratic biologic behavior. Therapeutic responsiveness may be unsatisfactory and there will be sustained remissions in individual dogs

Stage II dogs can still have a good prognosis after treatment including chemotherapy. Expected Survival times are over 18 months.