Anemia in Cats

What is Anemia in Cats?

Anemia is defined as a deficiency of red blood cells and hemoglobin (or both) in the blood. Red blood cells (RBCs) are the most common type of blood cell in the body and the main way oxygen is carried to the body’s tissues and organs. RBCs are made by bone marrow and released into the body’s bloodstream, where they circulate for their lifespan of about 70 to 80 days. As the cells age, they break down, and parts are recycled to form new blood cells.  

Hemoglobin is an iron-containing protein within the RBCs that carry oxygen molecules. When a cat is anemic, the decrease in RBCs and/or hemoglobin leads to decreased oxygen flow to the body’s organs. This decrease in oxygen to the tissues and organs may result in organ damage, and even failure. Anemia is extremely dangerous and can become life-threatening. 

There are two types of anemia: regenerative and non-regenerative.

Regenerative anemias are when the bone marrow produces enough RBCs to correct the anemia (or decrease the number of RBCs).

Non-regenerative anemias are when the bone marrow does not function properly and is not able to correct for the deficiency of RBCs.

In cats, sometimes both regenerative and non-regenerative anemias can exist at the same time.  

If you suspect your cat may be anemic, contact a local veterinarian immediately.

Symptoms of Anemia in Cats

Symptoms of anemia include some—or all of the following:

• Lethargy 

• Pale gums (sometimes the gums are yellow, indicating jaundice)

• Difficulty breathing or rapid breathing

• Increased heart rate

• Weakness or collapse

• Decreased appetite

Causes of Anemia in Cats

Anemia isn’t a disease itself but rather secondary to diseases or conditions in the body that cause anemia. The causes of anemia can be broken down into three broad categories: blood loss, destruction of RBCs, and a failure to produce new RBCs.  

Blood loss can be internal (inside the body), external (outside the body), or both. Some common causes of blood loss in cats include:

• Trauma, such as being hit by car

• Fleas/ticks that suck blood from the body. This can be very significant in newborn kittens

• Hookworm infestations that feed on the blood in the intestines

• Bleeding tumors 

• Severe stomach ulcers 

• Diseases that prevent proper blood clotting

• Anticoagulant rodenticide toxicity (when a cat ingests rat poison)

Destruction of RBCs also called hemolysis can occur due to the following:

• Immune mediated hemolytic anemia (where the cat’s immune system attacks and destroys its RBCs) 

• Feline leukemia virus (FeLV) infection or feline infectious peritonitis (FIP) 

• Certain blood parasites such as Mycoplasma haemofilis (formerly known as Haemobartonella felis), Cytauxzoon, and Babesia which are spread to cats by tick bites 

• Toxins and chemicals from onions, zinc, copper, or acetaminophen (Tylenol)

• Drugs, including antibiotics and antiparasitic agents

• Genetic diseases such as pyruvate kinase deficiency in Abyssinian and Somali cats

• Neonatal isoerythrolysis—a condition seen in newborn kittens when the blood type of the kitten and the mother cat are not compatible 

• Low phosphate, seen in refeeding syndrome

• Cancer 

Failure to produce new RBCs means the bone marrow that produces RBCs is unable to keep up with the demand for new RBCs. The bone marrow makes new RBCs continuously as they become old and deteriorate (the RBC lifespan is 70-80 days). When a cat is anemic, the bone marrow should be able to produce more RBCs to compensate.

Reasons for failure to produce new RBCs include:

• Anemia of chronic disease: Any chronic disease or illness can lead to anemia due to long-term inflammation that decreases RBC production. Chronic conditions include chronic infection, tumors, and disorders of the hormone system (such as hypothyroidism). This is the most common type of anemia in animals.

• Chronic kidney disease: The kidneys produce a hormone called erythropoietin, which stimulates the development of RBCs by the bone marrow. If kidney disease is present, the kidneys do not produce enough erythropoietin, decreasing RBC production (which leads to anemia). 

• Severe nutritional deficiencies or imbalances

• Feline leukemia virus (FIV) or Feline immunodeficiency virus (FIV)

• Autoimmune disease or inflammation affecting the bone marrow

• Chemicals or toxins affecting the bone marrow

• Cancer affecting the bone marrow or RBC directly

How Veterinarians Diagnose Anemia in Cats

While your vet may be suspicious of anemia due to the presence of pale gums or lethargy noted on a physical examination, anemia is ultimately diagnosed with a complete blood count (CBC) to evaluate the hematocrit (Hct), also known as the packed cell volume (PCV). The Hct and PCV are measurements of the percentage of blood volume that make up RBCs. In normal cats, 25 to 45 percent of the blood should be RBCs. Anemia is diagnosed by a Hct or PCV of below 25 percent.  

After a pet is diagnosed with anemia, the veterinarian will recommend additional tests to determine the underlying cause of the anemia. If there are no signs of external blood loss (bleeding from wound, nose, etc.), internal bleeding will be ruled out using diagnostic imaging such as X-rays and/or ultrasound of the cat’s chest and abdomen.

If no signs of bleeding are noted, your veterinarian will perform additional blood tests to check for evidence of RBC destruction (hemolysis). They may also recommend testing for diseases spread by tick bites, or other specialized tests submitted to a laboratory. 

A serum chemistry, electrolytes, and urinalysis should be performed to check organ function and assess other causes of anemia. Fecal examination is needed to rule out parasites and a FeLV/FIV snap test is another important test to help your vet determine the cause of your cat’s anemia.

If there is concern the cat’s bone marrow is not responding properly, your veterinarian may recommend a bone marrow aspirate or biopsy to collect a sample of bone marrow for analysis.  

Often, severely anemic cats will be sent to a local veterinary emergency hospital for hospitalization, 24-hour care, blood transfusions, advanced diagnostics, and consultation with specialists.  

Treatment of Anemia in Cats

In cases of severe anemia, blood transfusion will likely be needed. Cats have two major blood types (A and B), so blood typing is performed on the donor and recipient to help decrease the risk of transfusion reactions. Once the cat is stabilized, attention will be directed at identifying and treating the underlying cause of the anemia.  

Treatment will vary based on the underlying cause of the anemia but may include:

• Steroids

• Antibiotics

• Gastroprotectant medications

• Deworming medication

In a case of trauma, surgery may be needed to stop the bleeding and address the anemia. If the anemia is severe or persistent, additional transfusions, oxygen therapy, and other supportive care may be needed.  

Recovery and Management of Anemia in Cats

Severely anemic cats will likely need to be hospitalized for 2 to 7 days while they receive treatment for the anemia and the underlying cause of the anemia.  

Prognosis will vary significantly based on the underlying cause of the anemia. Most cats with mild anemia, when treated early, and in overall good health, will typically make a full recovery and have no long-term effects. However, cats that are severely anemic, or suffer from autoimmune diseases or cancer, can have a more guarded prognosis and require long-term medication and treatment.

The prognosis for cats with blood loss, secondary to trauma, will vary depending on the extent of the trauma and how quickly they receive treatment.  

If a pet parent suspects their cat is suffering from anemia, they should take their cat immediately to the local veterinarian emergency hospital for evaluation. Early diagnosis and treatment are keys to a good outcome.  

Anemia in Cats FAQs

---

---