To the FML -
 
    I have watched the recent debate on the merits of the drug Tribrissen
(the generic name for a combination of trimethoprim and sulfadiazine, both
sulfa drugs), culminating with BIG's message of yesterday and the apparent
unsubscription of four FMLers.
 
    Truly, I'm not sure what all of the fuss is about.  Hopefully my
comments may put this issue to rest without any more hullaballoo.  I have
already spoken to Starla Dill, the ferret's owner, and Carla Almaraz, who
acted as intermediary on this issue, so I don't think they would mind my
comments.
 
    Please don't mistake my objective manner as insensitivity to Starla's
loss - it is certainly a tragedy, but as I see it, an unavoidable death.
 
    Side effects of trimethoprim sulfa have been debated in the veterinary
literature for over 15 years now, with no firm consensus.  Most reports of
lethal side-effects are anecdotal, as T-S has been fed to numerous dogs
during testing and trial, and for many years, befroe the advent of more
sophisticated antibiotics, was a staple of the veterinary armamentarium.
 
    Trimethoprim-sulfa has been INCRIMINATED, but not proven to cause
several side effects in dogs (only meaning the dogs were taking the drug
when the effects were seen, but a cause-and-effect relationship was never
proven, even when similar doses were given to a number of dogs.) The side
effects, namely hepatotoxicity, and in a few animals, bleeding disorders,
are exteremly rare, considering the millions of animals that have received
tribrissen over the years.  Note that I am describing the syndrome in DOGS,
as there is no information on this condition in ferrets.
 
    The mechanism of tribrissen's effect on platelet function is unknown,
but is suggested to be it's ability to cause the formation of antibodies
which accidentally coat platelets and cause their destruction.  A similar
mechanism may cause damage to the blood vessels throughout the body.  Either
of these mechanisms MAY have resulted in the hemorrhages seen in Halie.
 
    However, let's not lose sight of the fact that these type of rare
idiosyncratic reactions may be seen with any number of drugs including
penicillin (Amoxicillin is probably the most widely used antibiotic in
ferrets.) Any time that you put a foreign chemical in your body, you run a
risk of causing an allergic reaction, which is what, simply put, was Halie's
undoing.  Tribrissen has save many, many more lives than it has taken - and
the reactions that it has caused are few and far between.
 
    Trimethoprim-sulfa should still have a place in the veterinarian's
pharmacy, but should be used only when indicated by bacterial culture and
sensitivity.  I would not, however, blame Halie's vet, nor condemn the drug
or it's manufacturer for Halie's extremely atypical reaction.
 
Bruce Williams, DVM, DACVP
Dept. of Vet Path, AFIP
[log in to unmask]  OR
Chief Pathologist, AccuPath
[log in to unmask]
[Posted in FML issue 1279]