http://www.fritzthebrave.com/

There seems to be possible connection between Bartonella and just about
any inflammatory disease.  However, if your cat has tested positive for
Bartonella, your vet will likely not want to begin any asthma treatment
until you have done a full 21-day course of antibiotics, because the
steroids which are used to treat asthma suppress the immune system.

Its very difficult to establish a connection between B. henselae and *any*
disease because a very high percentage of *healthy* cats are chronically
bacteremic.  B. henselae is a subtle bug- meaning that clinical signs can
develop in chronically infected cats only when they're stressed or secondary
from concurrent diseases.  IOW, the stress of his asthma might be bringing
on the symptoms. OTOH, his symptoms may have nothing to do with the B.
henselae infection since most infections in cats are subclinical.

If I were you, I'd treat his asthma *now*.  I would try inhalation therapy
first since very little of the drugs end up in systemic circulation.  Also,
ask your vet to show you how give your cat a subcutaneous injection of
terbutaline in the event of a serious attack. There's nothing to it- Its
just like giving a cat an insulin shot under the skin and it might save his
life.

If your email addy is good I can send you information on B. henselae that
you won't find online.

Best of luck.

Phil