🧬 Vet-Approved Guide to Multiple Myeloma in Dogs and Cats (2025) 🐶🐱

By Dr Duncan Houston BVSc

Multiple myeloma is a rare cancer of the immune system affecting dogs and cats. It involves abnormal growth of plasma cells—antibody-producing cells—in the bone marrow or organs like the spleen and liver. These overproducing cells disrupt normal blood function, cause organ damage, and produce life-threatening complications 🧫. In this 2025 guide, Dr Duncan Houston explains symptoms, diagnosis, treatment options, and prognosis 🩺.

🧠 What Is Multiple Myeloma?

Plasma cells are specialized white blood cells (B cells) that produce antibodies to fight infection. In multiple myeloma, plasma cells grow uncontrollably and crowd out normal blood cell production 🧬.

• 🔴 Fewer red blood cells → anemia
• ⚪ Fewer white cells → weakened immunity
• 🩸 Fewer platelets → increased bleeding risk

Plasma cells may accumulate in bone marrow (classic form) or in organs such as the liver or spleen, particularly in cats 🐾.

🧪 What Causes It?

The exact cause is unknown. Possible risk factors include:

• 🧬 Genetic predisposition
• 🦠 Certain viruses
• ☢️ Exposure to carcinogens
• ♻️ Chronic immune stimulation or illness

🔍 Symptoms of Multiple Myeloma

Signs are non-specific and can mimic other illnesses, making diagnosis challenging 🔬:

• 😴 Lethargy or weakness
• 🍽️ Loss of appetite or vomiting
• 💩 Diarrhea or loose stools
• 🥤 Increased thirst and urination
• 🚶‍♂️ Trouble walking or limb pain
• 🩸 Bleeding issues (e.g., nosebleeds, bruising, pale gums)

These symptoms are often due to anemia, kidney dysfunction, or abnormal blood clotting 🧠.

📋 Paraneoplastic Syndromes

Multiple myeloma often causes secondary illnesses due to plasma cell by-products or immune disruption:

• 🧪 Hypercalcemia: high blood calcium → vomiting, weakness
• 💉 Hyperviscosity syndrome: thick blood → poor circulation
• 🦴 Osteolysis: bone destruction → pain or fractures
• 🧬 Immune dysfunction: greater risk of infection

🧪 Diagnosing Multiple Myeloma

Because symptoms are vague, multiple diagnostic tools are used:

• 🩸 CBC (complete blood count): checks red cells, white cells, platelets
• 🧪 Serum biochemistry: assesses organ function, especially kidneys and calcium levels
• 🧫 Serum protein electrophoresis: detects abnormal protein spikes (monoclonal gammopathy)
• 💉 Urinalysis: checks kidney damage and protein loss
• 📸 X-rays or ultrasound: detect bone lesions and organ enlargement
• 🔬 Bone marrow biopsy: confirms plasma cell infiltration

A diagnosis is typically confirmed when at least two major criteria are met (e.g., protein spike, bone lesions, and plasma cell presence).

💊 Treatment of Multiple Myeloma

There is no cure, but with treatment, many pets experience symptom relief and improved quality of life.

1. 📉 Chemotherapy

• 💊 Melphalan – most commonly used drug
• 💊 Often combined with prednisone

Other options may include cyclophosphamide or chlorambucil, especially in cats or resistant cases 🧬.

2. 💉 Supportive Care

• 🩸 Blood transfusions (for anemia)
• 🧴 Pain relief (for bone pain)
• 🧪 Fluids and medications (for kidney support)
• 🩺 Antibiotics (to control infections)

3. 🧪 Monitoring

• 📆 Regular blood and urine tests
• 📸 Imaging for bone lesions or tumor spread

📊 Prognosis

Survival varies depending on species and treatment response:

• 🐶 Dogs: 220–930 days (approx. 7 months–2.5 years)
• 🐱 Cats: 42–281 days (approx. 1.5–9 months)

Without treatment, pets decline rapidly—treatment can significantly extend quality and quantity of life 🐾.

🧠 Key Takeaways

• 🧬 Multiple myeloma is a systemic cancer with immune and blood complications
• 💉 Early diagnosis and treatment = longer, more comfortable life
• 📋 Lifelong monitoring and support are essential

📲 Final Advice from Dr Duncan Houston

Multiple myeloma is complex, but not hopeless. With the right treatment plan and monitoring, pets can continue enjoying time with their families 💖. If your dog or cat shows signs like weakness, nosebleeds, or elevated blood proteins, ask your vet to rule out this condition early.

📱 Need help with treatment monitoring, chemotherapy planning, or quality-of-life decisions? Download the Ask A Vet App or visit AskAVet.com for expert care 24/7 🐶🐱.