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Feline Multiple Myeloma FAQ — Key Information Every Pet Owner Should Know

Oncology/CancerQ&AMeongsiljang Veterinary Advisory Board

Feline multiple myeloma is a rare but deadly blood cancer, and early detection is key to successful treatment. Here’s a summary of the essential information every pet owner should know.

What is feline multiple myeloma?

A condition characterized by abnormal proliferation of plasma cells in a cat's bone marrow

Feline multiple myeloma is a malignant tumor in which plasma cells proliferate abnormally in the bone marrow, adversely affecting both the blood and bones. The tumor cells produce abnormal proteins (monoclonal gammaglobulins) that appear in the bloodstream, and can lead to bone-destroying osteolytic lesions and pathological fractures. Systemic symptoms such as anemia, thrombocytopenia, neutropenia, hypercalcemia, and decreased kidney function may also occur. Early symptoms are often vague, making them easy for pet owners to overlook. Diagnosis is based on clinical and radiographic findings along with confirmation of monoclonal gammaglobulins in the blood, so it is important to consult a veterinarian for testing if any abnormalities are suspected.

Why is feline multiple myeloma not detected early?

Feline multiple myeloma often presents with no obvious symptoms in its early stages, making it easy for pet owners to overlook. Signs such as lethargy, pain, and weight changes can resemble those of other conditions, leading to confusion. As plasma cells proliferate in the bone marrow, gradual changes like anemia, thrombocytopenia, neutropenia, and bone lysis develop, making early detection challenging. If monoclonal gammaglobulin (abnormal proteins) is detected in blood tests, multiple myeloma should be suspected, and further diagnostic testing is necessary. However, monoclonal gammaglobulin can also occur in certain infectious diseases, such as feline infectious peritonitis, so differential diagnosis is essential. Regular health check-ups can help identify abnormalities at an early stage.

A veterinarian performing a blood test on a cat

What are the main symptoms of multiple myeloma?

The main symptoms of feline multiple myeloma include the following. If several symptoms overlap, consider visiting the vet early.

Lethargy and discomfort: Your cat may sleep all day, show reluctance to move, and have reduced activity due to pain.

Bone pain and osteolysis: Tumors can dissolve bone (osteolysis), causing pain, and weakened bones may fracture pathologically.

Anemia symptoms: Pale gums or ears, easy fatigue, and apparent shortness of breath may occur.

Tendency to bleed: Decreased platelet counts can lead to easy bruising or bleeding.

Renal dysfunction: If the kidneys are affected, drinking and urination patterns may change, and overall health may decline.

Symptoms of feline multiple myeloma: fatigue and lethargy

Signs requiring immediate veterinary visit

If your cat suddenly becomes unable to move or appears to have a broken bone, seek veterinary care immediately. This could be a pathological fracture caused by bone weakening from multiple myeloma. Prompt diagnosis and treatment can significantly improve survival rates.

How is multiple myeloma diagnosed?

Multiple myeloma is accurately diagnosed by combining the results of several tests. - Blood tests: If monoclonal gammaglobulin (an abnormal protein) is detected in the blood, suspicion of myeloma increases. - Serum protein electrophoresis: This analyzes the type and amount of abnormal proteins to confirm monoclonality. - Urinalysis (Bence Jones protein): This checks for abnormal proteins (Bence Jones proteinuria) excreted in the urine. - Bone marrow examination: This directly confirms whether plasma cells are proliferating abnormally in the bone marrow. - Radiography: This evaluates characteristic findings such as bone lysis or the risk of pathological fractures. However, since monoclonal gammaglobulin can also appear in infectious diseases like feline infectious peritonitis, a final diagnosis is made after differential diagnosis and by synthesizing the results of multiple tests.

What are the treatment options?

Treatment for feline multiple myeloma varies depending on the stage of the disease and the cat’s overall condition. - Chemotherapy: Anticancer drugs such as melphalan form the cornerstone of treatment, helping to slow disease progression and alleviate symptoms. - Corticosteroids (Prednisolone): These are frequently used in conjunction with chemotherapy. - Radiation Therapy: This may be considered on a case-by-case basis to manage localized lesions. - Surgical Excision: When feasible, tumor masses may be surgically removed. - Pain Management and Supportive Care: Adjunctive therapies are provided to relieve bone pain and support overall well-being, including nutritional support. A personalized treatment plan should be developed in consultation with your veterinarian.

Comparison of treatment options: Efficacy and side effects

Item	Chemotherapy (melphalan)	Corticosteroids	Radiation therapy
Efficacy	Suppression of disease progression and symptom relief	Used adjunctively alongside for symptom relief	Case-by-case local lesion control
Side effects	Bone marrow suppression (neutrophil/platelet reduction), gastrointestinal symptoms	Polyphagia, polydipsia, polyuria, decreased liver function, etc.	Local side effects may occur depending on the treatment site
Cost	Moderate	Low	Varies by equipment and hospital

Treatment choice depends on the cat's health status and the family's circumstances.

Precautions during treatment

During cancer treatment, a cat’s immune system weakens, making it highly susceptible to infections. Limit outdoor exposure and ensure the cat lives in a clean environment. Administer all medications exactly as directed by your veterinarian.

What can caregivers do?

A caregiver’s role is crucial in managing feline multiple myeloma. - Regular check-ups: During chemotherapy, blood counts should be monitored frequently. For melphalan treatment, blood tests (CBC) are recommended weekly for the first 4–6 weeks, then every 4–8 weeks thereafter. - Medication management: Administer medications at the correct times and dosages as directed by your veterinarian. - Dietary management: Help maintain your cat’s weight and condition by providing a nutritionally balanced diet as recommended by your veterinarian. - Environmental management: Provide a quiet space where your cat can rest comfortably and minimize stress. - Symptom tracking: Daily records of appetite, activity level, and elimination habits will facilitate better communication with your veterinarian. - Emotional support: It is important to handle your cat gently to prevent anxiety and provide a sense of stability in their daily routine.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Is feline multiple myeloma hereditary?

The exact genetic pathway of multiple myeloma in cats has not yet been identified. Diagnosis and management are based on clinical signs and blood and bone marrow tests, so it's best to consult with a veterinarian if you suspect your cat may have this condition.

Is multiple myeloma curable?

While a complete cure is difficult, the goal is to manage symptoms and maintain quality of life through chemotherapy drugs like Melphalan and appropriate treatment. Since survival time varies depending on the individual and the stage of the disease, it is important to consult with your veterinarian.

What should I feed my cat if it has multiple myeloma?

We recommend a diet that is easy to digest and nutritionally balanced. The specific diet should be determined in consultation with your veterinarian, tailored to your cat’s individual condition.

Is multiple myeloma related to a cat's age?

Multiple myeloma is most commonly reported in older animals, but the available evidence doesn’t clearly link it to a specific age in cats. Regardless of age, it’s best to have your pet checked if you notice any unusual symptoms.

Can regular checkups prevent osteosarcoma?

While prevention can be challenging, regular blood tests can help detect abnormalities such as monoclonal gammopathy at an early stage. It is important to identify any issues early through routine health check-ups.