Leukemia In Dogs - Causes, Symptoms & Treatment

Leukemia In Dogs - Causes, Symptoms & Treatment

Author Dr. Iva Pejnovic, DVM


Leukemia in dogs is defined as a proliferation of neoplastic cells in the bone marrow. The malignant cells may or may not be present in peripheral blood circulation.

What is leukemia in dogs?

Leukemia is a group of blood cancer. The disease usually begins in the bone marrow. An increased number of abnormal blood cells are not fully developed. These blood cells are called blasts or leukemia cells. The exact cause is unknown.

In humans, there are four main types:

  1. acute lymphoblastic leukemia (ALL),
  2. acute myeloid leukemia (AML),
  3. chronic lymphocytic leukemia (CLL)
  4. chronic myeloid leukemia (CML).

In dogs, it is most common ALL.

Acute lymphoblastic leukemia -ALL

ALL is lymphoproliferative disorder, defined as the presence of circulation prolymphocytes and lymphoblasts in blood. It is characterized by bone marrow infiltration and displacement of normal hematopoietic stem cells. Also, it may infiltrate other organs.

ALL is a disease of young to middle-aged dogs, with a median age of 5-6. Male to female ratio is 3:2.

ALL is characterized by the unexpected and quick increased number of large lymphoblastic cells. CLL is a slowly progressive form of leukemia, typically a disease of older dogs between 10-12 years old. The neoplastic lymphocytes are smaller than in ALL.

sick dog

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Symptoms of leukemia in dogs

Symptoms of leukemia are often nonspecific. Usually, there is an enlargement of the liver or spleen and lymphadenomegaly. Petechiae and ecchymotic hemorrhages may be present.

The first symptoms include

  • Weakness
  • Lethargy
  • Anorexia
  • Vomiting
  • Diarrhea

ALL is characterized by the rapid onset of clinical signs noted. Bone pain may be present. Bone marrow almost exclusively produces lymphoblasts, and there may be decreased production of other cells which can result in anemia, thrombocytopenia, or neutropenia. There are several signs that you may notice:

  • Appetite loss and loss of weight
  • Lethargy and weakness
  • Bruising and bleeding
  • Pale gums
  • Diarrhea and vomiting
  • Thirst and frequent urination
  • Fever
  • Swollen lymph nodes


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Causes of leukemia

In cats, there is the specific cause of leukemia - FeLV infection (feline leukemia virus), unlike in dogs, there is no specific cause. Some risk factors may include ionizing radiation, oncogenic viruses, and chemical agents.

Exposure to benzene or other toxins can also cause leukemia. But most of the vets believe it develops spontaneously. Because causes are not well understood, there are no reliable ways of preventing disease.


Properly identifying cancerous cells is the most important factor in diagnosing leukemia in dogs. Blood tests can result from higher liver enzyme activities, and CBC may indicate:


  • Normochromic
  • nonregenerative anemia
  • thrombocytopenia
  • lymphoblastosis
  • leukocytosis
  • leukopenia

Diagnosing needs to be done with live cells from bone marrow biopsy. Tests for diagnosing can include bone marrow cytology and molecular diagnosis - PCR.

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Treatment for leukemia in dogs

There is no therapy to cure leukemia, but it can put cancer into remission and restore proper white blood cell production. The fundamental therapy is antibiotics to treat the possible infection.

Aggressive therapy is necessary and includes chemotherapy protocol with a combination of drugs. Supportive therapy, such as nutrition supplementation, is also given.

The common drugs used are:

  • Prednisone
  • Vincristine
  • Cyclophosphamide
  • Doxorubicin
  • L asparaginase.

Because cancer is in the bloodstream, chemotherapy affects the full body.



The response to therapy is quite good but quite short-lived. Very few dogs survive complete treatment during 25 weeks. The prognosis for ALL is poor, and median survival is 5 months. The median survival time for CLL is 12 months to 2 years.

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Difference between lymphoma and leukemia

Lymphoma is a cancer of the lymphocytes, either body's immune systemne system of the body. Leukemia is a blood cancer which can affect any of the 3 types of cells in the blood.


Leukemia is a cancer of lymphocytes, representing an increased number of abnormal cells. In dogs most common is acute lymphoblastic leukemia. It usually captures middle-aged dogs with a median age of 5-6. Symptoms are nonspecific, usually connected with anemia and swollen lymph nodes. Therapy is used to put the disease in remission, and it includes chemotherapy and often supportive medications. The prognosis is very poor.

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