What Is Multiple Myeloma in Dogs?

If your dog has just been diagnosed with multiple myeloma, you’re probably trying to make sense of what this cancer actually is and what comes next. Multiple myeloma is a cancer of plasma cells, a type of immune cell that lives in the bone marrow. When those cells multiply out of control, they produce abnormal proteins that cause problems throughout the body.

But, here’s something worth holding onto: multiple myeloma is one of the more treatable cancers in dogs, and many respond well to therapy. Here’s what to expect, from early signs to diagnosis, treatment, and how to support your dog day to day.

What is multiple myeloma in dogs?

Your dog’s immune system is full of plasma cells, which normally produce antibodies to fight infection. In multiple myeloma, one of those plasma cells mutates and starts duplicating uncontrollably. The result is a plasma cell tumor, or plasma cell neoplasia, spreading through the bone marrow and crowding out the healthy cells the body needs.

As those abnormal cells multiply, they pump out a protein called a monoclonal protein (sometimes called an M-protein), which builds up in the blood and urine. This overload of abnormal protein, known as monoclonal gammopathy or hyperproteinemia (too much protein in the blood), is what drives many of the complications: kidney stress, thickened blood, nerve problems, and more.

Multiple myeloma is also considered bone marrow cancer because that’s where it originates and spreads. It tends to affect middle-aged to older dogs, and some breeds, including German Shepherds, appear to develop it more often than others.

What are the signs to look for?

Multiple myeloma affects so many systems at once that the signs can look like several different problems. Here’s what pet owners most often notice:

• Limping or bone pain: The cancer weakens bones from the inside, which can cause lameness or a reluctance to move. In some cases, this progresses to a pathologic fracture, meaning a break that happens without significant trauma, because the bone has been weakened by disease.
• Increased thirst and urination: High calcium levels in the blood (hypercalcemia) are a common complication, and they make dogs drink and urinate a lot more than usual.
• Lethargy and weakness: When healthy marrow cells are crowded out, your dog can become anemic (low red blood cell count) and simply feel wiped out.
• Unusual bleeding: The abnormal proteins can interfere with clotting, leading to nosebleeds, gum bleeding, or bruising.
• Recurrent infections: Healthy plasma cells produce the antibodies that fight bacteria. When they’re replaced by cancer cells, your dog’s immune defenses drop, making infections more frequent and harder to clear.
• Neurological signs: In some dogs, the disease or spinal bone involvement can cause weakness in the back legs or loss of coordination.

How is multiple myeloma diagnosed?

There’s no single test that confirms multiple myeloma. Your vet will typically build a picture from several sources:

• Bloodwork: A complete blood count checks for anemia and signs of immune suppression. A chemistry panel can reveal elevated calcium (hypercalcemia) and signs of kidney stress.
• Protein testing: A test called serum protein electrophoresis separates the proteins in your dog’s blood to look for that abnormal monoclonal spike.
• Urine tests: A substance called Bence Jones protein, which is essentially the overflow of abnormal protein from the blood, is often detected in the urine and is a strong indicator of the disease.
• X-rays: Bone X-rays look for the characteristic “punched out” lesions that multiple myeloma leaves in the skeleton, as well as any fractures.
• Bone marrow aspirate: This is the definitive test. The vet (often with sedation) uses a needle to collect a small sample of bone marrow, usually from the hip or leg bone, and examines it under a microscope to confirm the presence of abnormal plasma cells.

At this point, your vet will very likely refer you to a veterinary oncologist, a specialist in animal cancers, who will take over or co-manage your dog’s care.

What are the treatment options?

Multiple myeloma in dogs is not considered curable, but it is very often controllable. The goal of treatment is remission, meaning the cancer is suppressed enough that your dog feels well and the disease isn’t actively progressing.

The most common approach your oncologist may recommend is oral chemotherapy with two drugs: melphalan (a chemotherapy agent that targets rapidly dividing cells) and prednisone (a corticosteroid that helps reduce inflammation and supports the treatment). Both are given by mouth, which means your dog doesn’t need to be hospitalized for infusions.

Other supportive treatments your vet may recommend alongside chemotherapy include:

• Intravenous fluids to protect the kidneys and help manage hypercalcemia
• Pain medication to manage bone pain
• Antibiotics for active infections
• Bisphosphonates (drugs that help slow bone loss) in some cases

Prognosis and life expectancy

This is usually the question that’s hardest to ask, and the one that matters most. Multiple myeloma dog prognosis is actually more encouraging than many other canine cancers. Studies suggest that the majority of dogs respond to melphalan and prednisone treatment, with many achieving remission. Median survival times in dogs that respond well typically range from around 12 to 18 months, and some dogs live longer.

Dogs that don’t have kidney failure, severe neurological signs, or extensive bone involvement at the time of diagnosis tend to do better. Your oncologist is the best person to give you a realistic picture based on your dog’s specific case.

Does pet insurance cover multiple myeloma?

Yes, multiple myeloma is eligible for coverage under a Lemonade Pet accident and illness policy, as long as the condition isn’t pre-existing. That means your dog shouldn’t be showing any signs or symptoms before your policy starts or during your waiting period.

Bone marrow aspirates, specialist oncology visits, regular bloodwork rechecks, and months of chemotherapy add up fast, often reaching several thousand dollars over the course of treatment. Getting coverage in place while your dog is healthy is what makes it actually useful when you need it most.

Before we go

A multiple myeloma diagnosis is a lot to take in, and it’s okay to feel shaken by it. But this is also one of the canine cancers where treatment gives many dogs real, meaningful extra time. A good oncologist, a consistent treatment plan, and your attention at home make a genuine difference. Ask every question you have, keep your vet and specialist in the loop, and know that showing up for your dog every day, even on the hard ones, matters more than you might realize. And if your dog is still healthy, now is a good time to look into coverage before anything changes.

Frequently Asked Questions

A few quick words, because we <3 our lawyers: This post is general in nature, and any statement in it doesn’t alter the terms, conditions, exclusions, or limitations of the policies issued, which differ according to your state of residence. You’re encouraged to discuss your specific circumstances with your own professional advisors. The purpose of this post is merely to provide you with info and insights you can use to make such discussions more productive! Naturally, all comments by, or references to, third parties represent their own views, and Lemonade assumes no responsibility for them. Coverage may not be available in all states. Please note that statements about coverages, policy management, claims processes, Giveback, and customer support apply to policies underwritten by Lemonade Insurance Company or Metromile Insurance Company, a Lemonade company, sold by Lemonade Insurance Agency, LLC.  The statements do not apply to policies underwritten by other carriers.