Bartonella in cats: which cats should be tested?
In your feline practice it has been proposed to run Bartonella henselae serology on every healthy cat that comes in for vaccination, 'to find out which ones are dangerous and treat them'. Many come from feral colonies.
Which statement is correct?
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A. A seropositive cat has active bacteraemia and should be treated with antibiotics
Serology indicates exposure, often past, and does not predict bacteraemia. Moreover, treating healthy cats is not recommended because it does not reliably clear infection.
B. A seronegative cat cannot transmit Bartonella to people
Some seronegative cats are bacteraemic, especially young cats with recent infection. A negative result does not guarantee the cat is not a source.
C. Testing healthy cats is not recommended; it is reserved for blood donors and for cats with compatible signs in which other causes have been ruled out
Correct. In healthy cats the results do not change management, which relies on flea control. In donors it matters, because Bartonella is transmitted by transfusion, and tests are combined (serology plus PCR or culture).
D. A negative blood PCR rules out infection, because bacteraemia is continuous
Bacteraemia can be intermittent, so a negative PCR does not rule it out. That is why several tests are combined in donors.
lightbulb Key takeaway
Bartonella seroprevalence is high in colony and flea-infested cats, and most infected cats are healthy. Attributing signs such as uveitis, gingivostomatitis or fever to Bartonella requires first ruling out other causes and assessing the response to treatment.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.