Anemia is not a disease on its own, but rather, is a sign that there is an underlying health problem of some kind. This blood disorder occurs when an animal’s red blood cell count drops lower than normal. This decrease can be from blood loss, a decrease in the number of red blood cells produced, or an increase in the number of red blood cells destroyed by the body. Many diseases and health issues can cause a cat to become anemic.

Because red blood cells help transport oxygen to cells and tissues throughout the cat's body, if the red blood cell count drops quickly or gets very low, the cat will show signs of oxygen deprivation, which can include lethargy, pale gums, increased heart rate, and difficulty breathing.

Although the outlook for anemic cats depends on the underlying condition, most cats will recover with treatment and go on to lead normal and happy lives.

What Is Anemia?

Anemia is a common blood disorder not just in cats, but also in dogs, humans, and many other animals. An anemic cat or other animal has too few red blood cells circulating in its blood, or too little hemoglobin within its red blood cells. Hemoglobin, a type of protein, is the component of red blood cells that binds to oxygen and carries it to the cells throughout the body.

Anemia in cats is typically broken down into two broad categories: regenerative and nonregenerative. In regenerative types of anemia, red blood cells are lost or destroyed. In nonregenerative types of anemia, the production of red blood cells is suppressed. Both categories of anemia have many underlying causes.

Symptoms of Anemia in Cats

Symptoms of anemia can vary based on the underlying issue that's causing the problem, but there are some general symptoms to watch for. Two of the most common signs of long-term anemia in cats are lethargy—you'll notice your cat seems more tired than usual, or isn't interested in things that it used to enjoy doing—and pale gums.

If you take a peek into your anemic cat's mouth, you'll probably notice that its gums are paler than normal, and may appear almost white. This is due to a lack of red blood cells.

An anemic cat's heart rate also increases in an effort to get oxygen to the cells that need it. You might see your cat's breathing rate speed up in an effort to bring more oxygen into the body. Most likely, your pet will appear lethargic and won't be as interested in playing, grooming, or socializing as usual, as reduced oxygen levels leave muscles weaker than normal.

Some cats also lose their appetite when they're anemic and may drink more in an effort to replace lost blood volume. In severe cases, when a cat has lost a lot of blood, it may be unable to move or can become unresponsive due to a lack of oxygen to the brain.

If your cat is showing any of these symptoms, it should be evaluated immediately by a veterinarian.

Causes of Anemia

The usual lifespan of a circulating red blood cell is only two months, so the cat's body must continually produce new red blood cells to replace the old ones. The different causes of anemia are grouped based on whether the anemia is regenerative, meaning the underlying condition is causing red blood cells to be lost or destroyed faster than they can be replaced, or nonregenerative, meaning the underlying condition is suppressing the normal production of new red blood cells.

Causes of Regenerative Anemia

• Blood Loss: This can occur externally or internally. Blood loss can be caused by trauma or a major injury (like being hit by a car), blood-sucking parasites (including fleas, lice, and hookworms), stomach ulcers, and tumors.
• Hemolysis: The body is destroying red blood cells prematurely. This is generally due to an autoimmune disorder called immune-mediated hemolytic anemia, in which the cat develops antibodies to its own red blood cells.
• Toxins: Many toxins can cause destruction of red blood cells. Aspirin and other blood-thinning pain medications, certain antibiotics, toxic plants, heavy metals, and even certain foods can trigger anemia in a cat that ingests them accidentally.
• Infections: There are many infectious diseases caused by bacteria and viruses that include anemia as a symptom. Hemobartonella is one such bacterial disease. Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are common viral causes of anemia. Certain parasites can also cause anemia.
• Genetic Diseases: Some types of anemia can be inherited. The Abyssinian and Somali breeds are known to develop a specific type of anemia due to an enzyme deficiency.

Causes of Nonregenerative Anemia

• Poor Diet: An extremely poor diet or starvation can lead to nutritional deficiencies that result in anemia.
• Chronic Diseases: Diseases of the liver, adrenal, or thyroid glands, and certain cancers can all cause anemia. These illnesses cause inflammation, and this inflammation can decrease the body’s ability to make more red blood cells. This is the most common type of anemia seen in animals.
• Kidney Disease: A hormone called erythropoietin stimulates the body to make new red blood cells. This hormone is made by the kidneys. Kidney disease decreases the amount of erythropoietin the kidneys can make and is another very common cause of anemia in cats. Up to 65 percent of cats with advanced kidney disease have anemia.
• Bone Marrow Disorders: The bone marrow produces new blood cells, both red and white. Any disease affecting the bone marrow can cause anemia by repressing its ability to create new, healthy red blood cells. The most common diseases of cats that affect the bone marrow are cancer, feline leukemia virus, and feline immunodeficiency virus.

How Vets Diagnose Anemia in Cats

The diagnosis of anemia in cats is fairly straightforward. A blood test called a complete blood count (CBC) is the basic test used for evaluation. There are several components to a CBC. One is a count of white blood cells, which can be useful in diagnosing infections. However, it's the tests evaluating the red blood cells that are of most interest when a cat has symptoms of anemia.

Hematocrit: One component of the CBC is the hematocrit, which measures what percentage of a blood sample's volume is red blood cells. Normally, this should be around 25 to 45 percent, although different laboratories can have slightly different ranges. If the hematocrit is below 25 percent, a diagnosis of anemia is made.

Red blood cell count: The red blood cell count is another CBC component your vet will consider. This measures the actual amount of red blood cells in the blood sample. A typical normal range is 6.1-11.9 x 10⁶/µ l for cats. Anemic cats will be low in total red blood cells.

Hemoglobin: This is another important component of the CBC. This test measures how much hemoglobin the red blood cells contain. It's also usually low in an anemic cat. A typical normal range for cats is 9-15.6 g/dl.

Additional blood tests: Your veterinarian will probably also run other blood tests to check for your cat's overall health condition, as well as specialized tests to determine or rule out kidney disease and infectious diseases such as feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) because these viruses are frequent causes of anemia.

Fecal test: A fecal test will often be performed to check for intestinal parasites causing internal blood loss, as well. Occasionally, your vet might want to use a long needle to draw a sample of bone marrow to determine if the problem is due to a disorder of the marrow.

How to Treat Anemia in Cats

If the cat's anemia is severe enough to be life-threatening, an emergency blood transfusion and supplemental oxygen are usually required. For cats with mild to moderate anemia, however, treatment will focus not on the anemia itself, but on the underlying condition causing the problem. Your veterinarian will determine the necessary treatment for your cat's specific condition.

Prognosis for Cats With Anemia

Because there are so many underlying causes for anemia, it's difficult to generalize about the prognosis, but for most cats with mild anemia and simple underlying issues, the prognosis is quite good. For cats that have suffered severe trauma, however, or have ingested toxins, have cancer, or are in late-stage kidney disease, the prognosis is much more grave.

How to Prevent Anemia

Anemia is a symptom of many diseases, so preventing anemia is not always possible, but there are some specific things you can do to decrease the risk for your cat.

• Use a monthly parasite prevention product that kills fleas, ticks, lice, and intestinal parasites.
• Keep your cat indoors, or only allow them outside with direct supervision.
• Feed them nutritionally balanced cat food.
• Have them tested for feline leukemia and feline immunodeficiency viruses as recommended by your veterinarian.
• Prevent access to toxins.
• Take your cat in for veterinary exams at least once per year, and follow your vet's guidelines for routine blood tests.