Anemia in Cats With Cancer or Lymphoma: What to Expect

Name: Anemia in Cats With Cancer or Lymphoma: What to Expect
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Anemia in cats with cancer means the bone marrow is not making enough red blood cells to meet the body's needs. It is common in cats with lymphoma and other cancers, and it can range from mild to life threatening. Anemia in cats with cancer often changes how your veterinarian approaches treatment and monitoring.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Anemia means a low red blood cell count, measured as hematocrit (HCT) or packed cell volume (PCV).
Cancer can cause anemia through chronic inflammation, bone marrow infiltration, blood loss, or immune destruction of red blood cells [1].
Nonregenerative anemia (the bone marrow cannot respond) is more common with cancer than regenerative anemia [1].
Your veterinarian will use a complete blood count (CBC) and often a reticulocyte count to classify the anemia and guide treatment.
Treatment focuses on the underlying cancer plus supportive care such as transfusions, iron supplementation, or erythropoiesis-stimulating agents when appropriate.

What Anemia in Cats With Cancer Actually Means

Red blood cells carry oxygen. When their numbers drop, your cat's organs and tissues do not get enough oxygen. The body tries to compensate by increasing heart rate and breathing rate, but this only works for so long.

Veterinarians classify anemia in two main ways. Regenerative anemia means the bone marrow is still trying to make new red blood cells. The main types are blood loss anemia and hemolytic anemia (red blood cell destruction) [1]. Nonregenerative anemia means the bone marrow is not responding to the low red blood cell count [1].

In cats with cancer, nonregenerative anemia is more common. The bone marrow may be suppressed by inflammation, infiltrated by cancer cells, or damaged by chemotherapy. Sometimes the anemia is regenerative, especially if the cancer causes bleeding or immune-mediated destruction.

A very serious form of hemolytic anemia is immune-mediated hemolytic anemia (IMHA). In IMHA, the immune system does not recognize red blood cells as "self" and makes antibodies against them [1]. Sometimes these antibodies also attack young red blood cells in the bone marrow, so the anemia becomes nonregenerative [1]. If your cat has IMHA, your veterinarian may recommend specific immunosuppressive treatment. You can read more about this in Feline Immune-Mediated Hemolytic Anemia: Diagnosis and Management.

Signs of Anemia You May Notice at Home

Cats are good at hiding illness. Early anemia may cause no obvious signs. As anemia worsens, you may see:

Pale gums, lips, or inner eyelids
Lethargy or weakness
Reduced appetite or weight loss
Fast breathing or shortness of breath
Increased heart rate
Jaundice (yellow tint to gums, skin, or whites of the eyes) if red blood cells are being destroyed
Collapse or fainting in severe cases

Pale gums are one of the most reliable signs owners can check at home. If your cat's gums look white or very pale pink instead of a healthy salmon pink, contact your veterinarian. For a deeper look at this sign, see Why Is My Cat having pale pink gums? Anemia Shock and Cardiac Disease.

Some cats with cancer also have low white blood cells and platelets. When bone marrow damage is extensive, white blood cell levels usually drop first, then platelets, then red blood cells [1]. This means your cat may have a higher risk of infection or bleeding before anemia becomes obvious.

Causes and Risk Factors for Anemia in Cats With Cancer

Several mechanisms can cause anemia in a cat with cancer. Often more than one is at play.

Chronic Inflammation

Cancer causes long-term inflammation. Inflammatory cells release cytokines, which are proteins that decrease iron availability, shorten red blood cell lifespan, and interfere with bone marrow regeneration [1]. This is sometimes called anemia of chronic disease. Treating the underlying cancer usually improves this type of anemia [1].

Bone Marrow Involvement

Some cancers, especially lymphoma and leukemia, can infiltrate the bone marrow directly. Leukemia is a type of cancer marked by an increased number of abnormal white blood cells in the blood and bone marrow [2]. When cancer cells crowd the bone marrow, normal red blood cell production drops. This is a form of bone marrow cancer in cats, and it can cause severe nonregenerative anemia.

A rare example is acute erythroid leukemia, a bone marrow cancer that can cause nonregenerative anemia, increased nucleated red blood cells, and thrombocytopenia [3]. This condition can also cause pleural effusion (fluid around the lungs) if cancer cells spread to the chest cavity [3].

Blood Loss

Cancer can cause bleeding into the gastrointestinal tract, abdomen, or other sites. This leads to blood loss anemia, which is regenerative if the bone marrow can respond. If the bleeding is chronic, iron deficiency may develop and limit the bone marrow's ability to compensate.

Immune-Mediated Destruction

Some cancers trigger the immune system to attack red blood cells. This is IMHA. It can occur with lymphoma and other cancers. Cats with IMHA may test positive for feline leukemia virus (FeLV) on point-of-care ELISA tests even when confirmatory testing is negative, which can complicate diagnosis [4].

Chemotherapy and Other Treatments

Some chemotherapy drugs suppress the bone marrow. This can worsen anemia or cause pancytopenia, a condition in which all blood cell counts are low [2]. Your veterinarian will monitor blood counts regularly during treatment to catch this early.

Chronic Kidney Disease

Many cats with cancer also have chronic kidney disease (CKD). CKD is a common cause of nonregenerative anemia because the kidneys do not make enough erythropoietin, the hormone that tells the bone marrow to produce red blood cells [1]. If your cat has both cancer and CKD, anemia may be worse than either condition alone would cause.

How Anemia in Cats With Cancer Is Diagnosed

Your veterinarian will start with a complete blood count (CBC). The CBC measures red blood cells, white blood cells, and platelets [2]. It also provides the hematocrit (HCT) or packed cell volume (PCV), which is the percentage of blood made up of red blood cells.

A reticulocyte count is essential. Reticulocytes are young red blood cells. A high reticulocyte count means the bone marrow is responding (regenerative anemia). A low count means it is not (nonregenerative anemia) [1].

Your veterinarian may also recommend:

Blood chemistry panel to check kidney values, liver values, and iron levels
FeLV and FIV testing
Bone marrow aspiration or biopsy if bone marrow disease is suspected
Imaging (X-rays or ultrasound) to look for tumors, bleeding, or organ changes
Coombs test or other immune testing if IMHA is suspected

In one study of cats with suspected immune-mediated anemia, hematocrit at presentation ranged from 7% to 16%, and macrocytosis (larger than normal red blood cells) was recorded in 78% of cases [4]. This shows how severe anemia can be when the immune system is involved.

If your cat has lymphoma, your veterinarian may also stage the cancer to see how far it has spread. You can learn more about that process in Feline Feline Lymphoma: Diagnosis and Management.

Test	What It Tells Your Veterinarian
CBC with reticulocyte count	Whether anemia is regenerative or nonregenerative
Blood chemistry	Kidney function, liver function, iron status
FeLV/FIV test	Whether a viral infection is contributing
Bone marrow aspirate	Whether cancer cells are in the marrow
Ultrasound or X-rays	Whether there is bleeding, a tumor, or organ changes
Coombs test	Whether the immune system is destroying red blood cells

Treatment Options for Anemia in Cats With Cancer

Treatment depends on the cause and severity of the anemia. Your veterinarian will tailor the plan to your cat's specific cancer, overall health, and owner goals.

Treating the Underlying Cancer

The most important step is often treating the cancer itself. For cats with lymphoma, multiagent chemotherapy can improve both the cancer and the anemia. In one study of cats with renal lymphoma receiving COP-based chemotherapy (vincristine, cyclophosphamide, and prednisolone), 21 of 24 cats experienced clinical benefit at a median of 33 days after starting treatment [5]. This shows that treating the cancer can lead to real improvement.

Blood Transfusions

A whole blood or packed red blood cell transfusion can quickly raise the hematocrit and relieve severe signs. Transfusions are supportive, not curative. They buy time while other treatments take effect. In critically ill cats, transfusions may only provide transient improvement, and hematocrit can decline again [6].

Erythropoiesis-Stimulating Agents

These drugs stimulate the bone marrow to make red blood cells. They are most useful for anemia caused by chronic kidney disease. Your veterinarian will decide if your cat is a candidate. The dose is calculated based on your cat's weight and health status.

Iron Supplementation

If iron deficiency is contributing to the anemia, your veterinarian may recommend iron supplementation. The dose and form depend on your cat's specific needs.

Immunosuppressive Therapy

If IMHA is diagnosed, your veterinarian may prescribe corticosteroids or other immunosuppressive drugs. In one case report, a cat with pure red cell aplasia and amegakaryocytic thrombocytopenia recovered after corticosteroid treatment, and both diseases had not recurred by day 600 without medication [7]. This shows that some immune-mediated blood disorders can go into long-term remission.

Managing Side Effects

If chemotherapy is suppressing the bone marrow, your veterinarian may adjust the protocol or add supportive care. Never adjust chemotherapy doses on your own. Call your veterinarian if you notice new signs of weakness, pale gums, or bleeding.

Recovery, Outlook, and Long-Term Management

The outlook for a cat with cancer and anemia depends on the type of cancer, the cause of the anemia, and how well your cat responds to treatment.

Some anemias improve quickly once the underlying cancer is treated. Anemia of chronic inflammation often resolves when the cancer is controlled [1]. Immune-mediated anemias may respond to immunosuppressive therapy, sometimes with long-term remission [7].

Other anemias are harder to manage. If cancer has extensively infiltrated the bone marrow, the anemia may be persistent. Cats with bone marrow cancer in cats, such as leukemia or acute erythroid leukemia, often have a guarded prognosis [2][3].

Anemia can also affect how well your cat tolerates other treatments. In one study of cats undergoing subcutaneous ureteral bypass surgery, anemic cats were more likely to be hypotensive during the perioperative period and had a smaller reduction in creatinine after surgery compared to nonanemic cats [8]. There was no significant difference in survival to discharge or 30-day survival between anemic and nonanemic groups in that study [8]. This suggests that anemia may complicate treatment but does not always determine the final outcome.

Long-term management may include:

Regular CBCs to track hematocrit and reticulocyte count
Periodic blood chemistry to monitor kidney function and iron levels
Ongoing cancer treatment as directed by your veterinary oncologist
Supportive care such as appetite stimulants, anti-nausea medication, or fluid therapy
Transfusions if anemia becomes severe again

Your veterinarian will set a monitoring schedule based on your cat's specific condition. Some cats need weekly blood work during active treatment. Others may need it every few months once stable.

Prevention

There is no sure way to prevent anemia in a cat with cancer. The best strategy is to diagnose and treat the cancer as early as possible. Regular veterinary checkups can help catch problems before they become severe.

If your cat has FeLV or FIV, keep them indoors and away from other cats to reduce the risk of infections that can worsen anemia. Vaccinate against FeLV if your cat is at risk.

Feed a complete and balanced diet. Poor nutrition can contribute to nonregenerative anemia [1]. If your cat has kidney disease, your veterinarian may recommend a kidney-friendly diet.

Avoid giving your cat any human medications or supplements without asking your veterinarian first. Some common drugs can cause bone marrow suppression or bleeding.

Limitations and When to Contact a Veterinarian

Anemia in cats with cancer can change quickly. Contact your veterinarian right away if you notice any of these signs:

Gums that are white, very pale, or blue
Difficulty breathing or open-mouth breathing
Collapse or inability to stand
Vomiting blood or black, tarry stool
Sudden weakness or lethargy
Yellow tint to the gums, skin, or eyes
Bleeding that does not stop

Call your veterinarian the same day if your cat has pale gums but is still eating and acting mostly normal. Call immediately or go to an emergency clinic if your cat is struggling to breathe, has collapsed, or has blue gums.

Routine monitoring visits are important even when your cat seems well. Blood work can detect anemia before you see signs at home.

Every cat is different. Your veterinarian needs to examine your cat and review the test results to make specific recommendations.

Frequently Asked Questions

Can anemia in a cat with cancer be cured?

Sometimes the anemia improves when the underlying cancer is treated. Anemia of chronic inflammation often resolves once the cancer is controlled [1]. Immune-mediated anemias may go into remission with immunosuppressive therapy [7]. If cancer has extensively infiltrated the bone marrow, the anemia may be managed but not cured.

How long can a cat live with cancer and anemia?

It depends on the type of cancer, the cause of the anemia, and how your cat responds to treatment. Some cats live for many months or longer with good management. Others decline quickly if the bone marrow is heavily involved. Your veterinarian can give you a more specific outlook after evaluating your cat.

Is anemia painful for cats?

Anemia itself does not usually cause pain. The weakness, fatigue, and shortness of breath that come with it can make your cat feel unwell. If your cat has cancer that is causing pain, your veterinarian can prescribe pain medication.

Can I treat my cat's anemia at home?

No. Anemia in a cat with cancer requires veterinary diagnosis and treatment. Some supportive care, such as offering favorite foods or keeping your cat warm and calm, can help at home. But transfusions, immunosuppressive drugs, and other treatments must be given by a veterinarian.

Does anemia mean my cat's cancer is getting worse?

Not always. Anemia can be caused by chronic inflammation, which may not mean the cancer is progressing [1]. It can also be a side effect of chemotherapy. However, worsening anemia can be a sign that the cancer is advancing or that the bone marrow is more involved. Your veterinarian will interpret the trend over time.

References

Anemia in Cats - Cat Owners. Merck Veterinary Manual.
White Blood Cell Disorders, Leukemia, and Lymphoma of Cats - Cat Owners. Merck Veterinary Manual.
A rare case of acute erythroid leukemia (AML M6-Er) with pleural metastasis and malignant pleural effusion in a cat. The Journal of veterinary medical science, 2025.
Laboratory Changes Supporting a Diagnosis of Immune-Mediated Anemia in Cats With Initial Suspicion of Progressive Feline Leukemia Virus. Veterinary clinical pathology, 2026.
Ultrasonographic characteristics of renal lymphoma in cats receiving chemotherapy. Journal of feline medicine and surgery, 2025.
Hematologic and Renal Trends in Cats Undergoing Continuous Renal Replacement Therapy: A Retrospective Case Series with Molidustat Use. Veterinary sciences, 2026.
Pure red cell aplasia and amegakaryocytic thrombocytopenia in a cat. The Journal of veterinary medical science, 2025.
Association of preoperative anemia on perioperative complications and short-term outcomes in cats undergoing subcutaneous ureteral bypass. Journal of the American Veterinary Medical Association, 2026.