Veterinarians presented with a cat showing non-specific signs of lethargy and enlarged tender lymph nodes, possibly also with digestive and/or respiratory symptoms, will take a thorough history from the cat’s owner and conduct a complete physical examination. The initial evaluation probably will include taking blood and urine samples and performing routine blood work and a urinalysis on those samples. While the results of these tests can be helpful to ruling in or out other causes of the cat’s symptoms, unfortunately they usually don’t show consistent abnormalities in cats that have bartonellosis.
Several different advanced diagnostic tests can be used to identify the presence of Bartonella henselae or anti-Bartonella henselae antibodies in cats. These include immunofluorescent assay (IFA), polymerase chain reaction (PCR), blood cultures and Western blot, among others. All of the blood tests, except for the blood cultures, check for the presence of antibodies to the Bartonella bacteria. If a sufficient number of antibodies are present, then a positive diagnosis usually will be made. Currently, a Western Blot Test known as FeBart is one of the more popular diagnostic tests for bartonellosis in cats. However, even if a cat tests positive on one or more of these tests, it doesn’t necessarily confirm that Bartonella infection is the cause of the cat’s clinical problems, because so many cats are infected with Bartonella without showing any signs of being sick. In addition, some cats that harbor Bartonella don’t produce antibodies to the bacteria; blood tests will not catch the infection in those cases. Multiple blood samples are necessary to accurately test for bartonellosis using blood cultures; even when a number of separate blood cultures are conducted, the bacteria still may be missed. Additional tests are usually conducted to check the cat’s overall health status; these may include testing for FIV (feline immunodeficiency virus infection), FIP (feline infectious peritonitis) and FeLV (feline leukemia virus infection).
Because it is so difficult to confirm that Bartonella organisms are the real cause of symptoms in a particular cat, and also because so many domestic cats are infected with Bartonella, many veterinarians will start treating the cat for bartonellosis even before they have made a definitive diagnosis that the cat actually is infected. Unfortunately, there currently is no reliable treatment protocol that successfully eliminates a cat’s infection with these organisms. The most common “treatment” is to administer oral antibiotics for several months and then reevaluate to see if the animal’s symptoms have subsided.