Heartworm and flea control medication and Your DogPlease note: The information on our site is for everyone to read.Please use it as often as you like.
However, Ask Dr Mike is available only to subscribers of our Vetinfo Digest.Please do not send questions if you are not a subscriber.
Please use the search engine or one of the indexes to see if the information
you need is already online. Please see Subscriber info for details. Subscriber Info
The income from the subscriptions helps defray the cost of maintaining the site and allows us
to keep the large amount of information on www.vetinfo .com free to our readers.
Collies and monthly heartworm medication
Heartworm medication and Collies
Heartworm and flea control medication
Heartwom and flea and tick control
Program and lower seizure threshold
Heartworm medication reaction
Heartgard and Interceptor
Program - side effects?
also see Heartworm Disease
also see Flea problems
Collies
and Monthly heartworm Preventative
Question: I have recently been informed that collies should not
be given once a
month heartworm preventative because it can cause organ damage, seizures
and even death in some collies. Would this also apply to shelties
or
any other breeds? My source was the Collie club of America.
Thank you
Diana
P.S.
I do enjoy your Vetinfo Digest. Best newsletter I get.
Answer: Diana-
This is simply an error on the Collie Club of America web site. It is
easy
to verify this by going to the PubMed web site
(http://www.ncbi.nlm.nih.gov/PubMed/) and searching for the author
of the
quoted studies using "Paul AJ" as the search term. These are the articles
that this information was based on and ivermectin (Heartgard Rx),
milbemycin (Interceptor, Sentinel Rx) and moxidectin (ProHeart Rx)
are all
considered to be safe for use at the recommended dosages and did not
start
to cause problems in collies until about 10x the normal dosage for
ivermectin and milbemycin and toxicity was not seen with moxidectin
at up
to 30X the recommended dosage. This makes collies more susceptible
to the
effects than many breeds, since many dog breeds can tolerate dosages
that
are closer to 100X the heartworm prevention dosage but it still provides
a
very adequate safety range.
The once monthly heartworm prevention medications are much more reliable
than the daily medications in real life use. Both will work if given
according to directions, but I practiced when the daily medications
were
all that was available. We had between 5 and 20 dogs a year who would
turn
up positive for heartworms, whose owners really felt they were being
given
the medication, each year. With the monthly heartworm prevention
medications we have seen approximately 5 positive patients since these
medications
became available. If you live in an area in which heartworm disease
is
likely it is a much better choice to use the monthly prevention medications.
Please check this information for yourself before deciding not to use
one
of the monthly heartworm prevention medications -- it is easy to do
that.
Mike Richards, DVM
1/22/2001
Heartworm medication and Collies
Question: Dr. Richards,
I wrote to you before regarding heartworm
prevention. I told you I have a Borzoi and a Collie that
I give Interceptor. I made mention that I knew that
Ivermectin was downright dangerous to give a Collie, and your
reply was that "you give it to Collies without problems all the
time." I'd like you to investigate the use of Ivermectin in Collies
with the Collie Club of America. It is not acceptable and has
caused many untimely and unnecessary deaths. I trust you will,
I know you care.
Vox
Answer: Vox
Collies are more sensitive to ivermectin toxicity than other breeds.
However, the level of ivermectin
necessary to induce toxicity in collies is still very high compared
to the level used in Heartgard or
Heartgard Plus (tm). The dosage of ivermectin necessary to prevent
heartworm disease is 6ug/kg,
although it is possible to administer 12ug/kg using the recommended
dosing on the tablets, if a collie
weighs close to 50lbs. The dosage of ivermectin at which toxicity problems
start to become likely in
collies is around 50ug/kg (based on the study reported on the Collie
Club of America web site).
Most of the original problems reported occurred when ivermectin was
used for killing heartworm
microfilaria, which are baby heartworms circulating in the blood stream
after heartworms have
already invaded a dog's body. The dosage originally used for this purpose
was 50 ug/kg of
ivermectin -- and there were some severe reactions in collies and collie
related breeds at this dosage.
Ivermectin is available in formulations for large animal use which
some people try to compound into
medications usable for small animals, leading to some dosing errors
that have severely intoxicated
collies. I have personally treated five or six collies or collie related
breeds that people poisoned using
large animal ivermectin preparations in an attempt to prevent heartworms.
I have also treated a
number of beagles and hound breeds for this problem, as it is a common
practice among people
owning many dogs, such as hunt clubs. Lastly, ivermectin is used at
daily doses of 250 ug/kg for
demodex fairly commonly and ranging up to 600 ug/kg to treat resistant
cases of demodecosis.
While most dogs can tolerate this dosage, it will injure or kill some
patients. This is not something that
we would try in a collie, either. I am not aware of documented problems
with Heartgard or
Heartgard Plus at the recommended dosages for the purposes of heartworm
prevention. These
dosages are low enough that they do not cause problems.
Milbemycin toxicity has been studied in collies, too. The dosage of
milbemyin that causes toxic signs
in some collies is 5 times the usual dosage, according to an article
in the 1991 issue of the American
Journal of Veterinary Research, by Tranquilli, Paul and Todd (I mentioned
all three names because
Dr. Paul is the author who reported the studies on ivermectin on the
Collie Club of America web
site). This is approximately the same level of overdosage that causes
problems with ivermectin.
The Collie Club of America recommendation to use daily heartworm medication
containing
diethylcarbamazine (DEC) as an alternative is poor advice. I practice
in an area in which heartworm
disease is endemic. During the time that DEC was the only heartworm
preventative available, we had
between 5 and 20 patients a year, ON heartworm preventative medications,
who developed
heartworms. Since the two monthly preventative medications have become
available, we have
averaged less than 1 patient a year who is on heartworm prevention
medication who develops
heartworms.
I have not had a single client who we have dispensed Heartgard Plus
(Rx) or Interceptor (Rx) for
their collie report any reaction to the medication, at all. We have
had complaints in several other
breeds, usually suspicions that seizures might have been induced by
the monthly dose of heartworm
medication.
Mike Richards, DVM
11/29/2000
Heartworm and flea control medication
Question: Doctor would you let me know if there is a substitute
for Sentinel
(milbemyonoxime+lufnuron) to prevent heartworm desease and fleas in
my
dog. I am retired and find that Sentinel is real expensive.
Thank you, Ray
Answer: Ray-
Sentinel (Rx) is a combination of lufenuron, the active ingredient in
the
product Program (Rx) and milbemycin, the active ingredient of the product
Interceptor (Rx). Program controls fleas by preventing flea reproduction
and Interceptor prevents heartworms, hookworms, roundworms and whipworms.
It is possible to substitute other products that control these parasites
and often it is less expensive to use other medications in combination,
although it is a little less convenient.
There are four approved products for heartworm control in dogs at the
present time, ivermectin (Heartgard Rx), moxidectin (ProHeart
Rx),
selamectin (Revolution Rx) and milbemycin (Interceptor Rx, Sentinel
Rx). All work well for heartworm prevention. They vary in their
ability to
control other parasites but usually heartworm prevention is the major
concern. The cost of these products differs some and you may find you
can
save money by using a different heartworm preventative.
There are a great number of flea control products. The major advantage
of
using a separate flea control product, rather than a combined product,
such
as Sentinel (Rx) or Revolution (Rx), is that you can save money by
treating
for fleas only during the flea season, even if you must use heartworm
preventative all year in your area. Where we live, most of our clients
do
fine controlling fleas from June to November, so it is only necessary
to
use both a flea control and heartworm control product for six months
of the
year.
The best of the flea control products that we have used are Frontline
(Rx)
and Advantage (Rx). I think that Program and Sentinel work well for
dogs
that are confined and for house cats but are not as effective for pets
that
have free roam of the neighborhood or who spend time in places where
other
dogs are present, such as parks. If fleas are the only concern, it
is
probably less expensive to use Frontline, since it sometimes works
for 6 to
8 weeks to control fleas, especially for dogs that are not flea allergic
and can tolerate a small number of fleas prior to the time the product
is
reapplied. If it is possible where you live to use Frontline
every other
month and to use a less expensive heartworm prevention medication,
you
should be able to save some money on heartworm and flea control. This
is
even true if you have to use Frontline or Advantage for six months
of the
year and heartworm medicine all year, although the savings would be
smaller.
There are a number of over-the-counter flea control products but these
do
not work as well as Advantage or Frontline and good flea control usually
saves money since fleas cause a lot of skin disease.
Mike Richards, DVM
9/25/2000
Heartworm
Prevention and Flea and Tick Control
Question: Hi Mike:
I was reading the article
that you had written in the June issue
of the Vetinfo Digest on Medications for Heartworm Prevention
and Flea and Tick
Control. We live in an area of NE OH where ticks, fleas and heartworms
are
all prevalent.
I have been hearing
a lot about a product called Defend (EXspot
INSECTICIDE FOR DOGS). It supposedly:
Kills and repels Fleas
up to 4 weeks, Kills and Repels Deer
Ticks (lxodes dammini) Vector of lyme Disease up to 4 weeks.
Kills and repels
Mosquitoes. aids in prevention of Bkiid Feeding by Mosquitoes.
Vector of
Heartworm up to 4 weeks. Kills and repels Brown dog ticks.
(Rhipicephalus
sanguineus) up to 4 weeks. Kills and repels American Dog Ticks
(Dermacentor
variabilis for 2 to 3 weeks. Contains two 1cc applicators.
We also use Heartguard
Plus and I notice in your article as a
combination you like to use Frontline and Heartguard Plus.
In your opinion how does the
product Defend as I described above compare to Frontline. Are
their any
advantage or disadvantages that you can see in using Defend.
Thank you for your time, consideration, and cooperation. I hope
to hear from you soon, David
Answer: David-
We used Defend (tm) prior to the time that Advantage (tm) and Frontline
(tm) were available. Based on our experience, Defend is a very effective
tick control product which works well for 10 to 14 days. Defend (tm)
is a
moderately effective flea control product which rarely eliminates 100%
of
the fleas present on the dog. It is not effective enough to use on
a pet
with flea bite hypersensitivity or flea bite allergy but it may be
an
effective enough product to keep fleas to a liveable level for pet
without
these problems. I do not know what the current label says, but when
it was
sold through veterinarians the label said it could be applied at two
week
intervals. This interval would be necessary to get good control
of ticks
and moderate control of fleas. This product definitely does not control
mosquitos well enough to consider stopping heartworm control medications.
Defend is less expensive than Frontline, which is its sole advantage,
in my
opinion. Frontline is a much better product for flea control and is
as
effective for tick control. For pets with skin disease, Frontline is
usually effective enough to decrease the number of times treatment
for skin
disease is necessary, making total care of the pet less expensive despite
the cost of the product. For pets who are not sensitive to flea bites
and
where a low flea population may be tolerable, Defend may be less expensive
to use.
Mike Richards, DVM
8/24/2000
Program and lower seizure threshold
Question: hi gang...
i thought i remembered that someone or some folks out there give
their dogs
program?....someone in the clicker solutions list wrote the following:
" after doing quite a bit of research on my own I found out that
Program can lower a dogs seizure thresh hold. "
obviously i don't know what research she did, but i thought i'd
pass it
along for those of you who do use it or might use it. i don't
know if it's
a big deal, but it's always good to check these things out, right?
-----------------
So, Dr. Mike, are there any health concerns with
using
Program, month after month? Ought I to discontinue using
it?
Thanks so much.
Best regards, H
Answer: H-
Dr. Clemmons at the University of Florida has apparently made the statement
that Program (tm) and Advantage (tm) can lower the seizure threshold
in dogs
prone to seizuring, based on several emails I have received over the
last few
months. There is no published data to support this claim, that
I am aware
of, and I haven't heard of similar experiences from other veterinarians.
That
doesn't mean it isn't possible --- but it probably isn't a major concern
without at least a few other people making the connection.
If Program does lower the seizure threshold this would be a concern
for pets
known to have seizure episodes but not a problem for the general population
of dogs. Fleas are a much bigger concern for the average dog
and preventing
flea infestation is a major boost to good health. If Program
is working well
to control the fleas in your household it is almost certainly better
for your
dogs to continue using it. If one of your pups does develop seizures
that
would be the time to worry about whether or not it might be worthwhile
to
continue with the Program in that particular dog.
I am not aware of any other long term health problems associated with
the use
of Program at this time.
Mike Richards, DVM
12\20\99
Heartworm medication reaction ?
Q: My toy poodle was fine until recently when we started her on her heartworm medication, the one month chewable variety. The next day she became very lethargic and weak almost to the point of not being able to stand. I rushed her to the vet early this morning and they diagnosed her with a very low red blood cell count something like 14 instead of the normal 35. Her temperature was normal at 102, according to the vet. She was put on a large dose of steroids at 10:30 AM and this evening the vet called and said she had gained her red blood cell count very slightly. He seems to think she may be out of danger, but I'm still very concerned. The vet has no idea what may have caused this, but my suspicions lie with the heart worm medication having triggered this. The medication is Heartgard Plus by Merck which contains ivermectin/pyrantel. Could you please give me your opinion on this and any further recommended treatment? Also, does this sound curable? Thanks, Tom
A: Heartgard (Rx) and Interceptor (Rx) both come
under a lot of scrutiny as potential causes of immune medicated hemolytic
anemia (IMHA) and immune mediated thrombocytopenia (ITP) because they are
often the only medications that a pet is on when these occur. There is
no evidence at this time of an increase in the cases of IMHA or ITP in
dogs on these preventives. Recently, the once monthly flea treatments have
also been subjected to some suspicion since they are the newest medications
many dogs are on when these problems occur. There is also no evidence that
they cause either of these conditions, presently. That doesn't mean new
information won't come to light at some future time but I honestly do not
suspect these medications as culprits in these diseases.
Mike Richards, DVM
Heartgard (Rx) and Interceptor (Rx)
Heartgard (Rx) and Interceptor (Rx) both come under a lot of scrutiny
as potential
causes of immune medicated hemolytic anemia (IMHA) and immune mediated
thrombocytopenia (ITP) because they are often the only medications
that a pet is
on when these occur. There is no evidence at this time of an increase
in the cases
of IMHA or ITP in dogs on these preventatives. That doesn't mean new
information
won't come to light at some future time but I honestly do not suspect
these medications
as culprits in these diseases.
Mike Richards, DVM
Q: I have a 12 year old (18 lbs. Schnauzer) and
a 3 year old (75 lbs. collie) - The collie
is presently on heartworm medication and hypothyroid medication (2
pills daily - .05mm each)
- the collie is prone to seizures approximately every 8-9 weeks, we
believe from the
hypothyroidism. Will putting the collie on The Program flea control
pill monthly cause any
reaction or side effects with the other medications the dog is on?
Would it be safe? And the
12 year old is on no medications but on a special diet due to fatty
stones just surgically removed.
I want my animals safe and I don't like giving them medications unless
absolutely necessary.
Frontline flea control was expensive and did not work for my animals
last flea season. Topical
treatments are just not enough and I am suspicious that some of the
flea bombs and dips that
I have used in the past may have been toxic enough to have caused these
seizures in my collie.
The seizures have only been noticable since January of this year. Thank
you for your time.
Please respond. RJ in Pennsylvania
A: RJ - There is no evidence that I am aware of
that Program (Rx) will induce or facilitate seizures.
It should be safe to use in this situation and does not interact with
the medications listed.
It is always hard to figure out what is causing seizures and many times
it is impossible to do so.
That leaves a lot of room for guessing at causes. It is probably unlikely
that previous insecticide
use is the cause of the seizures but it is probably possible. Hypothyroidism
has been implicated
as a cause of seizures but it is probably not a common cause, either.
Supplementation of thyroid
hormone should reduce the incidence of seizures if hypothyroidism is
the underlying cause.
The topical version (vs. the spray version) of Frontline (Rx) has been
more successful on long
haired breeds such as collies, for us. If Program does not control
the fleas you might consider
trying this - or using both Program and Frontline or Advantage (Rx).
I hope that the seizures do diminish as time goes on.
Mike Richards, DVM
A note from Dr. Richards:
As of January, 2004, there is evidence
that collies have a specific genetic defect that makes them more susceptible to
reactions to ivermectin, as well as some other medications, including loperamide
(Immodium AD tm) and some chemotherapeutic agents. However, this discovery does
not change the information related to dosing. At the dosage recommended for
prevention of heartworm disease using ivermectin, there do not appear to
be substantiated reports of toxicity. Use of the FDA approved products (Heartgard
Rx, Heartgard Plus Rx and Iverhart Rx) is reasonable. Trying to dilute large
animal ivermectin for use in collies is not reasonable. At higher dosages, such
as those used to treat sarcoptic mange or demodectic mange, the potential for
reactions is much higher and the use of ivermectin in collies is not recommended
for these purposes. There are some very good reasons to consider using
ivermectin based heartworm prevention medications even with the knowledge that
collies may be more susceptible to overdosage reactions. One very good reason is
the ability of ivermectin to prevent heartworm infection better when a
month of medication is accidentally skipped than some of the heartworm
prevention medications, making it very useful when this situation seems likely
based on the past history of medication administration. Whether or not to use
ivermectin in an approved form for an individual collie is a decision that is
best made based an analysis of that particular collie's overall needs.