Multiple Myeloma in Dogs and Cats: Diagnosis and Care

By Dr Duncan Houston

Multiple myeloma can first appear as vague tiredness, poor appetite or a limp. Hearing that these changes may relate to cancer is difficult, especially when several tests are needed before the picture becomes clear.

The immediate priority is to identify complications that need treatment, then build a plan around comfort and the animal's response.

Quick Answer

Multiple myeloma is a cancer of plasma cells, which normally make antibodies. It can affect bone marrow, bones, kidneys and blood circulation, but the pattern differs between dogs and cats. Diagnosis combines laboratory results, imaging and tissue assessment; treatment commonly involves chemotherapy and support for complications. Severe weakness, bleeding or breathing difficulty requires urgent care.

Why can one cancer cause so many signs?

Abnormal plasma cells may crowd out normal blood-cell production and release large amounts of a particular antibody protein. Bone damage can cause pain or fractures. Kidney injury, high calcium, bleeding problems or abnormally thick blood can add further signs.

Myeloma-related disorders in cats may involve organs such as the spleen or liver, and do not always follow the classic canine pattern. A solitary plasma-cell mass is also not automatically the same as widespread myeloma.

Which signs need attention?

Signs	Possible concern	Action
Weight loss, reduced appetite or persistent lameness	Underlying disease needs investigation	Book a veterinary examination promptly
Increased thirst, vomiting or marked lethargy	Kidney or calcium complications	Contact the vet the same day
Collapse, unusual bleeding, sudden blindness or breathing difficulty	Potential serious systemic complication	Seek emergency care

How is the diagnosis confirmed?

A high protein concentration alone does not prove myeloma. Chronic infection, inflammation and other cancers can also alter blood proteins. The vet may request a blood count, chemistry profile, urine assessment and protein electrophoresis, which examines the pattern of circulating proteins.

Imaging can assess bones and internal organs. Bone marrow or other tissue sampling may be required to identify abnormal plasma cells. The Veterinary Society of Surgical Oncology's myeloma resource outlines the need for diagnosis and treatment monitoring rather than relying on one isolated result.

What treatment can achieve

Treatment usually aims for disease control and quality of life rather than a guaranteed cure. An oncologist may recommend an oral chemotherapy protocol, with drug selection and schedule adjusted for species, blood counts, organ function and response. Melphalan-based treatment is one established approach in dogs; cats need an individual plan.

Support may include pain relief, treatment of dehydration or high calcium, transfusion support and management of infection when present. Blood tests are essential because both disease and treatment can suppress normal blood cells. Published survival figures describe groups and cannot predict one animal's remaining time.

When is this an emergency?

Go to an emergency clinic for collapse, difficult breathing, uncontrolled bleeding, sudden inability to walk or a suspected fracture. During chemotherapy, marked illness, fever or repeated vomiting warrants immediate contact with the oncology team. Do not wait for the next scheduled blood test.

A practical home plan

Keep a daily note of appetite, comfort, walking, thirst and enjoyable activities.
Give medicines only on the written schedule and attend monitoring appointments.
Ask for specific chemotherapy handling and waste-cleaning instructions.
Avoid rough exercise if bone lesions are present.
Agree in advance which changes should trigger a same-day call or an emergency visit.

Common mistakes

Assuming every elevated globulin result means cancer.
Using survival averages as a deadline.
Changing chemotherapy doses or splitting tablets without instruction.
Adding supplements without checking interactions.

Can it be prevented?

There is no established home strategy that reliably prevents multiple myeloma. Routine assessment and prompt investigation of unexplained changes can identify problems earlier. Supportive care should preserve daily comfort without claiming to stop the underlying cancer.

Frequently Asked Questions

Is multiple myeloma contagious?

No. It is a cancer, not an infection passed between household animals.

Will chemotherapy make my pet very sick?

Side effects are possible, but veterinary plans aim to preserve quality of life and are adjusted when needed.

Can a normal X-ray exclude it?

No. Not every affected animal has visible bone lesions, so the complete test pattern matters.

How do we know treatment is helping?

The team assesses comfort, appetite, examination findings and relevant blood, urine or imaging changes.

A diagnosis is the start of a care plan, not a precise forecast. Focus on controlling complications and reviewing how your animal feels throughout treatment.

For clear explanations to support your veterinary conversations, visit ASK A VET™.