Bone Marrow Cancer (Myeloma) in Dogs

Multiple Myeloma in Dogs

Plasma cells are specialized white-blood cells, lymphocytes that have been altered to produce immunoglobulin, an immune protein or antibody necessary for fighting disease. Multiple myeloma is an uncommon cancer that is derived from a clonal population of cancerous (malignant) plasma cells in the bone marrow.

Three of four defining features must be present for a diagnosis of multiple myeloma: immune protein from a single clone of cells (known as a monoclonal gammopathy), seen as a spike in the gamma region of a protein analysis of the blood (known as a protein electrophoresis); cancerous plasma cells or a high number of plasma cells in the bone marrow (known as plasmacytosis); destruction of areas of bone (known as lytic bone lesions); and a particular type of protein found in the urine (known as Bence Jones [light-chain] proteinuria).

Multiple myeloma occurs in German shepherd dogs and other purebred dogs more often than mixed-breed dogs, and primarily in middle-aged or older dogs (6-13 years).

Symptoms and Types

Multiple myeloma is attributed to bone infiltration and destruction of the bone, effects of the proteins that have been produced by the tumor (such as increased protein in the blood leading to sludging of the blood and kidney damage), and infiltration of organ(s) by cancerous cells. Symptoms depend on the location and extent of the disease.

• Weakness, sluggishness (lethargy)
• Lameness is seen in 47 percent of affected dogs
• Bone pain and weakness is seen in 60 percent of affected dogs, with concurrent destruction of areas of bone
• Fever
• Partial paralysis
• Dementia with generalized discomfort or uneasiness seen in 11 percent of affected dogs
• Labored breathing
• Increased thirst and increased urination is seen in 25 percent of affected dogs, with increased levels of calcium in the blood or kidney dysfunction
• Urinary incontinence
• Enlarged liver and spleen
• Excessive bleeding from needle punctures to collect blood or to administer intravenous medications and/or fluids
• Bleeding involving the gastrointestinal tract
• Bleeding – especially from the nose or mucous membranes (the moist tissues of the mouth, eyes, and other areas of the body) is seen in 36 percent of affected dogs.
• Bleeding in the back part of the eye and blindness, retinal hemorrhage, or dilated retinal vessels is seen in 35 percent of affected dogs
• Pale gums and other moist tissues of the body (mucous membranes)
• Detached retina
• Glaucoma
• Inflammation of the front part of the eye including the iris
• Coma (rare)

Causes

Unknown

Diagnosis

You will need to give a thorough history of your dog’s health, and onset of symptoms. The history you provide may give your veterinarian clues as to which organs are causing secondary symptoms. Along with a thorough physical examination, your veterinarian will also conduct a thorough ophthalmological examination on your dog, if the eyes are showing symptoms of a diseased state.

Symptoms for multiple myeloma resemble those of several other diseases. Your veterinarian will need to rule out a number of other possibilities for the symptoms, such as infections, other types of tumors, and immune-mediated illnesses. To do that, your doctor will conduct a complete blood profile, including a chemical blood profile, a complete blood count, and a urinalysis. Diagnostic imaging will include X-rays of the vertebra and limbs to look for bone lesions, and ultrasound to examine the internal organs.