Lymphoma in Dogs
Lymphoma in dogs (canine lymphosarcoma) is a cancer of the lymphatic system and is a common canine cancer. What causes lymphoma? What are the symptoms and how is this type of cancer treated? Read on and find out!

The lymphatic system is a series of “tubes” and glands (lymph nodes) in the body that are responsible for fighting infections and is an important part of the body’s immune system.

The cells in the lymphatic system is a type of white blood cells called lymphocytes, which attack and destroy viruses, bacteria, etc. and are also active in cancer surveillance.

The lymphatic system has its own circulatory system in which the lymphocytes travel around the body in a clear fluid called lymph.

What is Lymphoma?

Occasionally, lymphocytes, the very cells that are supposed to protect the body against cancer, can develop into cancer cells themselves.

The result is lymphosarcoma, or commonly known as lymphoma.

The most common form of lymphoma is the multicentric form, which makes up about 80% of all cases.

In this form of lymphoma, cancer cells can be found throughout the lymphatic system, in many different locations of the body.

Lymphoma can spread very easily via the “tubes” that connect the whole body, Once lymphoma occurs, it is always assumed to have spread, because of the high mobility of the cells involved.

Lymphoma in dogs is common, especially among middle-aged and older dogs – Those from 5 to 9 years of age are susceptible.

In canine lymphoma, the lymph nodes are most commonly affected although other organs can also be affected.

For example, the liver and spleen are common areas for lymphoma as well.

Other organs that can be affected include the wall of the stomach or intestines. Sometimes, lymphoma can occur in the heart, the kindey, or the bone marrow. Occasionally, it occurs in the skin, the brain, or the eye.

Causes of Lymphoma in Dogs

As in other forms of cancer, the exact cause of lymphosarcoma in dogs is not known.

However, it seems that certain breeds of dogs are more predisposed to lymphoma than others.

They include the Golden Retrievers, Boxers, Bulldogs, Bassett Hounds, Cocker Spaniels, Labrador Retrievers, Rottweilers, St. Bernards, Scottish Terriers, and Airedale Terriers.

It has also been found that airborne carcinogens (cancer-causing agents) such as herbicides, paints, etc. may trigger lymphoma in dogs.

Electromagnetic fields, such as those around high voltage circuits or power lines, are also thought to be a possible trigger.

Symptoms of Lymphoma in Dogs

Since different organs can be affected by canine lymphoma, the signs and symptoms of this cancer vary rather greatly.

In most cases, common symptoms include:

  • Weight loss
  • Loss of appetite
  • Lack of energy
  • Lethargy

If the lymph nodes are involved, the affected nodes will first become bigger, then it will return to its normal size only to become bigger again.

Dogs with the liver and spleen forms of lymphoma usually just show signs of appetite and weight loss, and a lack of energy.

If the stomach or intestinal wall is affected, the dog may vomit and have diarrhea.

Lymphoma affecting the kidney can cause vomiting, increased thirst and frequent urination.

Lymphoma of the heart can cause heart failure.

The skin form of lymphoma in dogs will cause crusting of the skin and sometimes blistering.

Lymphoma affecting the brain can cause problems such as seizures, blindness, wobbliness, and erratic behaviors.

If the eye is affected, eye swelling, discoloration, and blindness can result.

If the bone marrow is affected, low red and white blood cell counts and low platelet counts can occur.

The dog will show signs of anemia (due to low red blood cell counts), may have frequent infections (due to low white blood cell counts), and bleeding can occur from the nose or in the skin, in urine or feces, or in the whites of the eyes (due to low platelet counts).

Diagnosis and Treatment of Lymphoma in Dogs

Lymphoma in dogs can be diagnosed with a number of tests, including:

  • Blood tests
  • Urinalysis
  • X-rays or ultrasound
  • Fine-needle aspirates of the affected area
  • Biopsy

Once a positive diagnosis has been made, the next step is to evaluate how advanced the disease is so as to plan an appropriate treatment.

As mentioned above, because of the high mobility of the cells involved, this cancer can spread very easily. In fact, more than 80% of dogs show signs of metastasis by the time of diagnosis.

The conventional treatment of choice for lymphoma in dogs is chemotherapy.

There is a drug mixture called COPLA which is a combination of cyclophosphamide, vincristine, prednisolone, L-asparaginase, and doxorubicin. The survival rate with this drug therapy is about 6 to 10 months.

Signs of cancer usually go away for about 6 months.

Single-drug therapy (using doxorubicin) is also possible and more convenient because it involves fewer threatments.

About 4 in 5 dogs will respond to this drug and surive for about 9 months. About one in 3 dogs will survive for one year.

Recently, half-body irradiation is also being used to treat some cases of canine lymphoma.

Understandably, lymphoma in dogs is never curable with surgery due to its widespread (whole body) involvement.

Related Pages: