I dislike the toxicity of heartworm preventatives, but I
accept them as necessary in certain geographic areas. The
southern states, TX, and coastal areas anywhere with marsh
flats would all be representative of areas where heartworm
preventative is probably important to use. Weather in these
types of areas is conducive to a long life cycle in the
heartworm; and TX and the southern states have a lot of
already infected animals - which means there is a much
better chance of a mosquito biting an infected dog and
passing the infection on to other dogs. So, people living
in these types of areas need to continue with the
preventative.
In NY, at Smith Ridge Veterinary Center (where I am Medical
Director), we probably don't sell more than 30 or 40 boxes
(3 doses per box) per year (that's total sales for all sizes
combined). 95% of our clients don't use heartworm
preventative. But they do religiously test for heartworm
*twice* a year. If there was to be an infection, catching
it early, by testing twice a year, means that it can be
treated using the standard heartworm preventative. In 8
years, I can remember hearing about 3 cases of heartworm in
our practice. Two were dogs who had been in FL during the
winter (where heartworm is a serious problem) and one was a
dog who lived on the Long Island shore in tidal marshes
(where the mosquito population is outrageous). In our area,
heartworm is not a huge problem. But infection *is*
possible. So people have to decide where their comfort zone
is.
if you decide you have to use Heartgard, you can minimize
the administration. First, Heartgard was proven during its
development to work for 45 days. The drug company convinced
the FDA to let them label it as a 30 day drug because
consumers are supposedly too stupid to be able to remember
to give a drug unless it's monthly. 45 days is just too big
a mental challenge for us. So, right off the bat you can
dose it at 45 days instead of 30 and therefore reduce the
administrations per year.
Second, if you live in the northern climes you can take
advantage of that. Heartworm lifecycles are disrupted
whenever the temperature drops below 57 degrees for even a
few hours out of 24. Below my signature is more info about
the heartworm lifecycle. Basically what you'll read is that
as long as you're living in northern weather, you can stop
giving heartworm meds from late Oct. through late March. If
you give it every 45 days, you are then reducing
administration to 4 or 5 times per year. In reading the
info below, note that the presence of mosquitoes alone does
not pose a risk. There are times in Dec. and Jan. I've seen
mosquitoes during a thaw. But the temperatures do not
support infection. Many vets don't realize this, and that's
why they try to convince people to use HW meds year-round.
It's simply not necessary.
Again, this is a comfort zone issue. I don't use any
heartworm meds and could never feel comfortable routinely
forcing my dogs to ingest pesticides. But my choice isn't
right for everyone. If you do feel you need to use them,
just minimize the administration (every 45 days, only in the
warmer months if weather allows that).
Hope some of this helps -
Dr. Marty
The mere presence of mosquitoes does not necessarily
indicate a heartworm risk. The lifecycle of the heartworm
(HW) and transmission from the mosquito to the dog is
dependent on fairly restrictive conditions.
Once the mosquito has ingested HW microfilariae the weather
has to cooperate before the microfilariae can mature into
third stage infective larvae that can be transmitted.
Maturation requires the equivalent of a steady 24-hour daily
temperature in excess of 64 degrees F (18C) for
approximately *one month*. When the temperature drops below
the developmental threshold of 57 degrees F (14C) for only a
few hours (as would be typical during the evening and night
during late fall and throughout the winter in northern
climes) HW maturation is immediately retarded, even when the
average daily temperature supports continued development.
Once the temperature rises and remains steady, the HW can
mature at a much faster rate. At 80 degrees F, the
microfilariae can mature to the infective stage in just 10
to 14 days. It is only when they reach the infective stage
that they can be transmitted to the dog by a mosquito bite
and pose a risk to our dogs.
So, for those in northern climes, the presence of mosquitoes
during a thaw does not represent a HW risk.
For those who are willing to run a HW test twice a year, you
can safely avoid administering HW medication year round (if
you live in northern climes). If you test in late Oct. (or
anytime the weather is *consistently* below 57 degrees for
at least part of the day or night) and your dog is clear of
heartworms, you could stop administering the meds. Test
again in late March, verify that the dog is still
heartworm-free, and then resume the meds. Your animal is
then free of unneeded chemicals for at least 5 months of the
year. Chemicals, especially the kinds that can kill
parasites, are not benign. They may be beneficial in some
respects, and they may be necessary at certain times and in
certain areas - but they are still not benign. If you have
the luxury of a climate that allows you to reduce your dog's
exposure to chemicals, why not take advantage of it?
I KNOW THIS WAS A LONG, BUT IT WAS VERY HELPFUL TO ME, IT CAME FROM DR. MARTY GOLDSTEIN........
