Feline Infectious Anaemia (FIA) is caused by Haemobartonella felis, a tiny, microscopic bacterial parasite which attacks the cat’s red blood cells within the circulation. Damaged cells may die or be destroyed at an increased rate by the spleen, leading to anaemia.
Although FIA is caused by an infectious agent, it is not necessarily a problem in other cats living in the same house. The way FIA is spread between cats is uncertain; cat bites and fleas may spread the parasite but other methods may also be involved. Fighting is known to represent a risk of spread of infection. Flea infestations should be treated promptly — the presence of fleas may make anaemia of any cause more severe. Even if your other cats do become infected this may not result in any anaemia or other problems.
Cats are very good at hiding anaemia until it is quite severe. The earliest indicators may be pallor of the mucous membranes — the conjunctiva (lining of the eye), gums and tongue appear white or pale instead of their normal pink colour.
It can be difficult to assess the mucous membranes in some cats. Occasionally they may appear rather pale but there are causes of pallor other than anaemia. As the anaemia becomes more severe, the cat may become lethargic and breathless if stressed, or after any exertion.
There may be loss of condition, poor appetite, weight loss and occasionally high temperatures. Sometimes jaundice is seen, but usually only in severe, acute cases.
How is FIA diagnosed?
Diagnosis is difficult. It relies on identifying the tiny organisms microscopically on specially prepared and stained blood films. These organisms are so small they are hard to recognise, particularly if present in low numbers. Diagnosis is further hampered by the fact that parasite is sometimes found on blood cells of normal cats with no anaemia.
Finding FIA in a cat without anaemia would not necessarily be considered significant. There are many other possible causes of anaemia in cats other than FIA, and identifying it in an anaemic cat may not necessarily mean that other causes of anaemia may not also be involved.
Treatment of FIA can also be difficult. No specific drug can be relied upon to eliminate the parasite. However, in the majority of cases, a variety of different drugs can be used to control FIA. Other diseases may also be present in cats with FIA and it is thought that the effects of these other diseases/factors, including stress, may contribute to enabling FIA to cause disease.
Successful treatment may depend on resolving any other disease problems the cat is showing. In severe cases, where the cat becomes very weak, a blood transfusion may be life-saving.