Those anemic blood suckers known as vampires might be the height of fashion (see: True Blood, Twilight), but there’s nothing stylish about the condition. Anemia is caused by the loss or destruction of a large amount of red blood cells, which can happen in the case of an infection with some viruses or parasites, certain immune-mediated disorders, drug reactions, or a disease such as cancer. Signs of anemia include tiredness, exercise intolerance (difficulty exercising), decreased appetite, and pale gums, though cats with mild anemia may not have any signs at all. A severe anemic may need a blood transfusion, and in all cases the underlying cause of the problem must be treated.


If your cat has anemia don’t panic. Though severe anemia is life threatening and requires immediate veterinary attention, mild cases can be easier to reverse or manage.

Anemia develops when the number of red blood cells in the bloodstream is reduced. Since they’re responsible for the transport and delivery of oxygen throughout the body, a deficiency in red blood cells can be potentially catastrophic to the entire system.

There are many causes and types of anemia, ranging from simple blood loss or the destruction of red blood cells within the body as part of a specific disease process to the inability of the body to produce enough red blood cells.

Signs and Identification

Because red blood cells carry oxygen, which is essential for all basic bodily functions, the most common signs of anemia are lethargy and exercise intolerance. Decreased appetite and pale mucous membranes (the gums, for example) are typical as well. Mild anemia may not be evident except through blood testing.

Diagnosing anemia definitively is done in the laboratory. Most veterinarians can perform a quick blood test called a packed cell volume (PCV) in the hospital. The PCV indicates the percentage of red blood cells in the bloodstream. If a cat’s PCV is lower than the normal range, anemia is diagnosed.

Other blood tests can offer more detailed information regarding the anemia, such as whether the body is losing vs. destroying red blood cells and if it’s producing new red blood cells to replace them. Among these, the CBC (complete blood cell count) is the most common and critical. It evaluates the individual components of the blood, a fundamental first step in the evaluation of any anemia.

In cats, the most common anemia-inciting processes include:

  • Infection with a virus, such as feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV), or a parasite (Mycoplasma haemophilus)
  • Blood loss from severe flea infestations (especially in kittens)
  • Immune-mediated disease (a condition in which the body’s immune system attacks its own red blood cells)
  • Bleeding into the gastrointestinal tract as a result of disease or severe inflammation
  • Reaction to certain drugs or exposure to certain toxins
  • Cancer (may decrease red blood cell production or lead to bleeding from a tumor)
  • Kidney disease (may lead to a decrease in red blood cell production)
Diagnosis of these can be achieved with a battery of tests, including blood testing (such as a biochemistry panel), urinalysis, specific testing for viruses, bacteria and parasites, and imaging techniques like X-rays, ultrasound, and sometimes more sophisticated testing (such as CT scanning and the surgical biopsy of specific tissues).

Affected Breeds

All breeds of cats can develop anemia, though some may suffer very rare forms related to specific genetic diseases.


In cases of anemia resulting from either acute or chronic loss or destruction of a large amount of red blood cells, a blood transfusion may be recommended (or required) for survival.

As previously mentioned, severe anemia results in a significantly reduced ability of the blood to deliver oxygen throughout the body and, most importantly, to vital organs such as the brain. Therefore, a blood transfusion is necessary to help deliver oxygen and nutrients to major organs and other parts of the body. Occasionally, multiple transfusions are required before the cat’s body can produce enough red blood cells on its own.

Other treatments for anemia will ultimately need to be tailored to the underlying cause.


Certain causes of anemia may be preventable. For example, to reduce the risk of infectious diseases and vehicular trauma, indoor living is recommended. Vaccination, parasite prevention, and preventing cats from roaming outdoors are also considered basic ways to protect cats from conditions that can cause anemia.

This article has been reviewed by a Veterinarian.