Feline Infectious Anemia

What causes Feline Infectious Anemia (FIA)?

Certain mycoplasma organisms are the cause of FIA. In cats, M.haemofelis, Candidatus M. haemominutum, and Candidatus M. turicensis are the most common causes. Cats can have more than one type of mycoplasma causing the infection.

These species of mycoplasma attach to the cell wall of the red blood cells. Other forms of mycoplasma attach to the respiratory or bladder surfaces and do not cause FIA. When the bacteria enter the cat’s bloodstream, it attaches and enters the red blood cells. This causes the red blood cells to become damaged. As the body recognizes this, it begins to filter out and attack the damaged red blood cells, leading to anemia.

How can my cat Feline Infectious Anemia?

FIA spread is not fully understood, but mosquitoes, fleas, and ticks are likely vectors and able to spread the disease. Blood transfusions and catfights are other possible ways to spread infections between cats. Mother cats can even spread the infection to their kittens, but it is not known if they are infecting the kittens before birth, during birth or when nursing.

Cats with compromised immune systems, such as cats with FIV or FeLV infections seem to be at higher risk.

Symptoms of Feline Infectious Anemia

Infected cats can have very mild anemia with no noticeable symptoms, to severe anemia causing illness and potentially death. Up to 33% of cats infected with M. haemofelis will develop fatal anemia if left untreated. The Candidatus species often cause much less severe illness to no obvious illness unless the cat is immunocompromised already.

• Pale to white gums
• Depression
• Increased breathing rate
• Increased heart rate
• Weakness
• Weight loss
• Yellow discoloration to the skin or eyes, also called Icterus
• Enlarged lymph nodes
• Enlarged spleen
• Fever may or may not be present
• Reduced appetite

How does mycoplasma cause Feline Infectious Anemia?

Since the mycoplasma attaches to the red blood cell wall, it damages the cell membrane causing the red blood cell to become more fragile and die sooner. The cat’s own immune system will detect the altered red blood cells and can start attacking them, causing additional cell rupture and worsen the anemia.

Cats infected with M. haemofelis will not show any symptoms for at least 1-3 weeks after they have been infected. Then about 1-2 months or longer post-infection, the anemia develops, and clinical symptoms may be present. If the body can mount a good immune response, the mycoplasma numbers decline, and the cat can go into recovery and regain a normal red blood cell level. Many cats that clinically recover will still harbor the parasite for months or even the rest of their life! If the cat gets stressed causing a reduced immune system response, the mycoplasma infection can flare up and cause illness again.

How is Feline Infectious Anemia diagnosed?

After a complete physical exam, your vet will likely recommend starting with some basic blood work to assess the red and white blood cells in addition to evaluating liver and kidney enzymes. Viral testing for FeLV and FIV is also often recommended. Cats with FIA will often have low red blood cell levels and abnormal appearing red blood cells. They may have increased liver and kidney enzymes if the anemia is severe and they are also dehydrated, causing secondary damage to these organs.

Occasionally your vet may be able to see the mycoplasma organisms on the red blood cells, but this is not always present or easy to find.

A PCR test is the test of choice for diagnosing FIA by looking for the DNA of the mycoplasma species. This test will often have accurate results 1-2 weeks post-infection.

My cat was diagnosed with infectious anemia. What is the treatment?

Certain antibiotics have been effective in treating mycoplasma infections. Treatment is often needed for 4 to 8 weeks. The longer treatment course has better success in resolving the carrier state.

Some cats with severe anemia also need a steroid or other immunosuppressive medication in addition to antibiotics. A blood transfusion is sometimes necessary. IV fluids, appetite stimulants, and other supportive care may also be needed.

Keeping cats indoors only and on year-round flea and tick control can reduce their risk of acquiring FIA.

Read more:

Hyperthyroidism in Cats

Cancer (Neoplasia) in Cats

Can cats develop heart disease?

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