>developed a hard lump at the site which remains today, 16 days later.
>My other 3 ferrets had their vaccines the same day, but none of them have
>this lump.  My vet is out of town for a week, should I be concerned, or
>will it go away on it's own?
 
At this point, I would not be concerned.  Hard lumps at the site of vaccine
are almost always the result of a reaction of the body against the vaccine
and the formation of an inflammatory nodule.  This is not the normal
reaction, but it it not a major problem, either.
 
Usually what we do is give it a month or so - if it hasn't resorbed by that
time, then we remove it (it probably has been walled off by the body and at
that point, resorption is possible.
 
What causes these?  Well, sometimes it is abnormal placement of the vaccine
into the skin rather than the subcutaneous tissue below, or that it is put
into an area which is poorly perfused by blood vessels, etc.  It is an
uncommon occurrence at any rate.
 
Could it be a tumor, as we occasionally see at sites of vaccination in
cats?  Very unlikely - it has been reported once, as opposed to the vastly
more common inflammatory nodule.  That's why we don't have to rush to
surgery.
 
With kindest regards,
Bruce H. Williams, DVM, DACVP
 
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[Posted in FML issue 3404]