Dogs

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Lymphoma

Lymphoma is a cancer of the white blood cells known as lymphocytes, and the disease may originate in any lymphatic tissue in the body, including the lymph nodes, spleen, liver, bone marrow, and thymus.

It may also however affect the skin, eyes, central nervous system, gastrointestinal tract, liver, and lungs. 

This cancer can be aggressive if left untreated, but may respond favorably to chemotherapy, adding months and sometimes years to a pet’s life.

Causes

The exact cause of lymphoma is unknown but a genetic predisposition may exist, because certain breeds, including the golden retriever, boxer, and bull dog, seem more prone.

Clinical Signs

Clinical signs depend on the area of the body affected. 

Most commonly one or more of the lymph nodes are enlarged, and some dogs may also have enlargement of the liver or spleen.

Depending on site of disease, other signs include breathing difficulties, blindness, seizures or lumps on the skin.

Some dogs may present with a fever and poor appetite, and may be losing weight.

Diagnosis

With enlarged lymph nodes which can be felt on a clinical examination (multicentric lymphoma), diagnosis can be relatively straightforward, but if the tumour is within a more internal organ it can be more difficult to detect and diagnose.

The tests performed do depend on location, but at Acorn we may recommend:

·      A complete blood count, biochemistry profile or urinalysis

·      Fine-needle aspiration of a lymph node or mass, with examination of cells under the microscope

·      Biopsy of enlarged lymph nodes or other organs

·      X-rays and/or ultrasound to evaluate for internal organ involvement

·      Bone marrow aspiration if bone marrow involvement is suspected

Treatment and Prognosis

Treatment depends on the organs involved, but most cases require chemotherapy as the disease is spread throughout the body.

A variety of chemotherapeutic protocols are available, consisting of combinations of oral and injectable medications. 

Modern protocols are able to provide maximum effect, with minimal distress and nausea to the patient, but serious discussion is recommended before the process is embarked upon.

The goal of chemotherapy is to achieve long-term remission and good quality of life.

Prognosis is best in dogs that achieve complete remission, and tolerate the chemotherapeutic medications. 

Treatment of multicentric lymphoma in dogs has an approximate response rate of 80-90%, with average survival times of 9-12 months after the start of treatment. 

Unfortunately lymphomas involving other organs, such as the skin, the intestines, or the respiratory system, or cases with very high blood calcium levels, have lower remission rates. 

In dogs that do not receive chemotherapy, survival time may be as short as 4-6 weeks and in these patients, oral steroids may be used temporarily to alleviate some of the clinical signs.

In almost all cases lymphoma will eventually come out of remission, with recurrence of clinical signs such as lymph node enlargement or spread of the cancer to other organ systems.  Sadly these dogs respond far less well to repeat courses of chemotherapy drugs.

At Acorn we believe that serious thought and discussion is required between vet and client before the decision as to whether to undergo chemotherapy or not is taken. We always place your pet’s interests first and aim to give an informed and realistic appraisal of prognosis and outcome.