Understanding Feline Infectious Anemia

There are a number of infectious organisms that cause feline anemia or the lack of red blood cells; however, the parasitic disease itself has been renamed "feline hemotropic mycoplasmosis", which literally means a cat blood infection of mycoplasma organisms. Feline infectious anemia, also known as hemobartonellosis, affects cats of all ages and breeds. In addition to some degree of anemia, clinical signs vary from lethargy and depression to shock and fever.

In an effort to rid itself of the parasite, the body's immune system destroys its own red blood cells because they appear as invaders since the parasite attaches itself to the red blood cell's outer membrane. Cat anemia develops if too many red blood cells are destroyed.

Modes Of Transmission

Cats become infected by bites from blood-sucking insects, such as fleas, ticks or mosquitoes. It can take up to one month after infection before adequate numbers of parasites are present in the blood before the cat becomes sick. The mortality rate is highest during this month. The cat becomes a permanent carrier even if the cat recovers because stress can reactivate the infection. Fleas on carrier cats can infect other cats by traveling onto, and then biting, them. Pre-existing medical conditions, cat diseases or illnesses makes cats more susceptible to infection.

At highest risk are those cats that roam outside during the spring and summer, 4 to 6-year old males, non-vaccinated, without flea control prevention, with a history of cat fights and/or with an immune-suppressive virus or feline leukemia. Cats can be infected through insect bites, blood transfusions or in the case of kittens by an infected mother.

Symptoms Vary

Some cases of this feline blood disease are mild while others can be so severe they result in death. Some anemic cats will eat dirt or litter in an attempt to obtain iron.

Symptoms include:

  • Sudden or gradual weakness
  • Anemia
  • Body tenderness
  • Fever
  • Pale/yellow tinged mucous membranes of the nose or gums
  • Weight loss or anorexia
  • Depression
  • Rapid respiratory and/or heart rate
  • Fatigue
  • Decreased appetite
  • Enlarged liver or spleen
  • Very responsive bone marrow (trying to produce red blood cells to replenish those being destroyed)

Phases of Feline Anemia

There are four phases of feline anemia:

  • Pre-parasitemic: lasting 2 to 21 days, infected but no clinical signs or organisms detectable in the bloodstream
  • Acute: lasting 2 to 4 months, clinical signs and the detection of the parasite in the blood occurs intermittently
  • Recovery: varying in duration, mild anemia with no apparent clinical signs and minimal phases of parasitemia
  • Carrier: possibly lasting for years, clinically normal with organism rarely detectable in the bloodstream

Tests To Confirm Diagnosis

Infected cats experience alternating phases whereby the parasite is present in the bloodstream and then absent making diagnosis difficult since a negative test may not mean that the parasite is not present, only that the sampled blood was taken during the "non-parasitemic" phase. Isolation of this organism in a blood culture is not possible since the organism lacks cell walls. Within a matter of three hours, the number of infected cells can range from 90% to 1%.

Tests include:

  • Complete blood count
  • Urinalysis
  • Coombs test
  • Testing for feline leukemia and immunodeficiency
  • Serum chemistry panel
  • PCR analysis

Since some tests produce a false negative for the parasite, the PCR tests for parasite DNA to confirm the disease.

Treating Feline Anemia

Generally there is a 65% to 75% survival rate depending on the severity and the response to treatment. Antibiotics, such as tetracycline and doxycycline, are prescribed for at least 3 weeks. Although controversial, corticosteroids, such as prednisolone, are used in selected cases. Prednisolone suppresses the immune system so that the red blood cells are not destroyed so rapidly. In the most severe cases, blood transfusions and intravenous fluids are used.

Prevention is the best way to fight this disease. Vaccinations, flea and tick control, keeping cats indoors and reducing the probability of fights will help prevent exposure to this disease as well as many others.