For clarification on another point-- heartworm treatment using monthly doses
of HeartGuard (ivermectin)-- I wanted to circulate this. A friend of mine
who is a vet practicing on the east coast has been using Heartguard on
heartworm positive dogs in his practice for about 8 years with excellent
results; in fact, he has treated over 100 dogs, with only a few remaining
positive post-treatment.) I think there is still some difference of
opinion amongst vets about its effectiveness and safety -- at least, in
Austin, it seems about half the vets I spoke to agreed that it was a
reasonable treatment for asymptomatic dogs (especially big dogs with big
hearts, who have better tolerance), while others only consider Heartguard as
a preventative and will only recommend for treatment the arsenical
adulticide (which has its own risks as decaying adult worms circulate
through the dog's bloodstream like so many bloodclots). Here is what the
American Heartworm Association says on the subject; they are understandably
extremely cautious in making their official recommendations (thus, the
suggestion that the dog be examined every 6 months), but even with their
cautions, this seems to be an treatment worth considering in asymptomatic
dogs.
Terrie
Ivermectin
Continuous monthly administration of prophylactic doses of ivermectin, alone
or in combination with pyrantel pamoate, is highly effective against late
precardiac larvae and young (<7 month post-infection) adult heartworms.
Comparable adulticide capability of the other macrocyclic lactones has not
been reported. The adulticide effect of ivermectin generally requires more
than a year of continuous monthly administrations and may take more than two
years before heartworms are eliminated completely. The older the worms when
first exposed to ivermectin, the slower they are to die. In the meantime, the
infection persists and continues to cause disease. Therefore, long-term
continuous administration of ivermectin generally is not a substitute for
conventional arsenical adulticide treatment. If arsenical therapy is declined,
a lengthy course of prophylactic doses of ivermectin will gradually reduce the
number of adult heartworms, but in chronic mature infections this may not be
clinically beneficial. Exercise should be restricted in dogs treated with
prophylactic doses of ivermectin as the adulticide.
The results of a
recent study in which monthly ivermectin was administered to client-owned
heartworm infected dogs for two years indicated that this method of killing
adult heartworms should not be used in dogs with signs of heartworm disease or
very active dogs, and if used in asymptomatic dogs, the dogs should be
examined by a veterinarian at least once every four to six months until all of
the worms are dead. As worsening of radiographic signs may be observed,
periodic radiographic evaluations may be useful in monitoring the treatment.
By the way, I don't know if you guys know about this web site...
I recalled it said something about spaying before treatment...and I looked it
back up after the comment by the white GSD group. I meant to do it earlier
and actually send them the info, but since Amy had already replied I left well
enough alone. Anyway, thought you guys might want to see it.
F. Spay/neuter
surgery of heartworm positive dogs: Many of the dogs rescued from the
hurricane aftermath are intact. Shelters may face legal, logistical and
ethical constraints regarding releasing these intact dogs to foster homes and
adopters. Some veterinarians experienced in working with heartworm
positive dogs report a preference for spaying and neutering heartworm positive
dogs prior to treatment provided the dog is not in heart failure.
If not altered prior to treatment, it may be preferable to delay
surgery until 60 days after adulticidal treatment.3 If the
more conservative treatment approach outlined above is followed this would
mean delaying surgery by a minimum of 6 months, creating a significant risk of
unwanted puppy production as well as difficulties in follow-up.
If surgery is performed prior to adulticidal treatment, caution
should be exercised to avoid fluid overload. Any standard anesthetic protocol
is acceptable.
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