Leukemia is a cancer of the blood. It occurs when there is an abnormal increase in the number of white blood cells in the bloodstream or the bone marrow.
There are different blood cells in the bone marrow, such as lymphocytes, platelets, monocytes, etc. Any one of these blood cells can give rise to cell-specific leukemias.
For example, lymphocytic leukemia is a malignant mutation of the lymphocytes (white blood cells).
Since lymphocytic leukemia is more common in dogs than other forms of leukemia, this page focuses on lymphocytic leukemia in dogs.
Regardless of the type of blood cell involved, leukemia is a result of genetic mutation in the bone marrow structure. This causes the bone marrow to over-produce a particular white blood cell.
At the same time, it also causes the bone marrow to under-produce other blood cells that the body needs to survive.
Acute and Chronic Leukemia in Dogs
Leukemia is further divided into acute and chronic stages.
Note that the terms “acute” and “chronic” have a slightly different meaning when it comes to leukemia. They refer to how mature the cancer cells look.
Lymphocytes are made in the bone marrow or lymph nodes. They undergo several stages of development before they are released into the bloodstream.
An acute leukemia is caused by cancerous lymphocytes that are in their earlier stages of development. A chronic leukemia is caused by lymphocytes that are more developed.
Acute leukemias are generally more malignant than chronic leukemias.
In acute leukemia, the cancerous lymphocytes can quickly spread through the blood stream to other sites in the body, most typically the liver and the spleen.
Both stages (acute and chronic) of leukemia in dogs are rare.
Acute leukemia usually affects middle-aged dogs or older (6 years or older). Chronic leukemia occurs more frequently in older dogs (10-12 years of age).
Symptoms of Leukemia in Dogs
In cases of acute leukemia in dogs, the bone marrow has suddenly become too busy producing the cancerous lymphocytes. As a result, other blood cells (e.g. platelets, red blood cells, etc.) are in short supply.
Due to a deficiency of red blood cells, a dog with acute leukemia will show symptoms associated with anemia, such as:
- Pale gums
- Color of tongue is pale pink to white
- Lack of appetite
- Weight loss
Not having enough platelets will lead to blood clotting problems. So the dog will have a tendency to bleed or bruise easily.
White blood cells are the immune system’s first line of defense. So, not having enough healthy white blood cells will lead to poor immunity. The dog may have recurrent infections and delay in healing time.
Unlike acute leukemia which can develop very fast, chronic leukemia takes months or even years to develop.
About half of the dogs diagnosed with chronic leukemia show no symptoms at the time of diagnosis.
This form of leukemia is usually discovered on a routine blood check. In fact, many dogs with chronic leukemia can survive for up to two years without chemotherapy.
Causes of Leukemia in Dogs
As in other forms of cancer, the exact cause of canine leukemia is unclear.
It is suspected that certain breeds may be genetically predisposed to the disease.
Also, as in humans, canine leukemia may result from radiation and certain chemicals and possibly some types of viruses.
Diagnosis and Treatment of Leukemia in Dogs
Diagnosis of canine leukemia include the use of:
- Blood tests (complete blood count)
- Biochemical profile
- Bone marrow aspirate
To determine if the cancer has spread to other sites in the body, the vet usually uses the following procedures:
- Chest and abdominal X-rays
- Abdominal ultrasound
- Fine needle aspirate of abdominal organs or lymph nodes
The conventional treatment for canine leukemia is chemotherapy.
Chemotherapy does not cure leukemia, but may put the disease into remission for several months or longer.
Typical chemotherapy drugs for acute leukemia include prednisone, vincristine, cyclophosphamide, L-asparginase and doxorubicin.
Typical drugs for chronic leukemia include prednisone, chlorambucil, and cyclophosphamide.
Dogs with chronic leukemia have a better prognosis than those with acute leukemia. Even with aggressive chemotherapy, only about 30% of dogs with acute leukemia can achieve remission.
Without any drug intervention, most dogs with acute leukemia die within a few weeks.
Caring for Your Dog with Leukemia
Understandably, dogs with leukemia (especially those undergoing chemotherapy) have a weakened immune system. It means they are more prone to fall victim to infectious diseases.
Therefore, if your dog is unfortunately diagnosed with leukemia, avoid places like dog parks, kennels, etc. where your dog may easily get infectious diseases from other dogs.
While a healthy dog can recover from a bout of kennel cough without too much effort and suffering, a dog with leukemia may easily develop secondary infections, and even pneumonia.
Also, as mentioned above, dogs with leukemia can bruise and bleed easily because they don’t have enough platelets. Bear that in mind when exercising or playing with your dog. No rough housing! If you have young children at home, be sure to tell your kids to handle your dog with more care.