Hello pilot-ga and thank you for your question.
It looks like moxidectin is quite safe, but there has been a report of
undesirable side effects (lethargy, anorexia, ataxia, and tremors) in
a dog after 3 months of treatment. Based on this result, the
recommendation for small animal practice is that "[u]ntil more
information is gathered on its toxicity in dogs, one should take the
same precautions as with extra-label use of ivermectin. As moxidectin
is more lipophilic than ivermectin, it should be used carefully in
thin or debilitated animals."
So why is moxidectin considered safe for use? According to the same
source quoted above,
"The wide margin of safety for ML endectocides [like moxidectin] is
attributable to the fact that mammals do not have glutamate-gated
chloride channels; these compounds have a low affinity for other
mammalian ligand-gated chloride channels and do not readily cross the
blood-brain barrier."
NEW APPROACHES TO THE TREATMENT OF CANINE DEMODICOSIS
http://www.boston-terriers.com/demodex.htm
Moxidectin appears to be so safe that it is on the road to being
approved for use in humans. In fact, it was developed and tested
through the MACROFIL project, a World Health Orgainzation (WHO)-based
project which is developing it as a macrofilaricide, i.e., a treatment
that kills adult worms in humans.
Final results of moxidectin trials in animal models were reviewed by
WHO in March 2000. These pre-clinical studies have shown it to fulfil
many of the criteria for a potential macrofilaricide: easy to use,
safe and effective.
TDR at the interface of research and control
www.who.int/tdr/publications/tdrnews/pdf/news62.pdf
And it is an effective drug:
"Properly timed per os monthly prophylactic doses of ivermectin (6-12
µg/kg body weight), milbemycin oxime (0.5-1.0 mg/kg body weight) or
moxidectin (3-6 µg/kg body weight), or topical selamectin (6-12 mg/kg
body weight) are completely effective in preventing development of
adult heartworms. To achieve these results, administration should
begin within one month following the start of the transmission season,
and the last dose should be given within one month after transmission
ceases."
AHS Guidelines
http://www.heartwormsociety.org/ahsguide.htm
There have been good results with lambs too. One report describes
lambs who were drenched in moxidectin, and apparently suffered no ill
effects; they gained significantly more weight than lambs drenched in
another drug, ivermectin:
"The weight gains of 164 3-4-month-old Romney ewe lambs following
treatment with either moxidectin (Cydectinreg.) or ivermectin
(Ivomecreg.) oral drenches in a cross-over design experiment were
compared. In the experiment, one group of 79 lambs was drenched
initially with moxidectin and 29 days later with ivermectin. A second
group, comprising 85 lambs, had similar treatments but given in the
reverse order. On both treatment occasions the dose for each group was
calculated to provide the recommended minimum dose of 0.2 mg/kg for
the appropriate anthelmintic to the heaviest animal in that group and
all animals were given the same dose. The two groups were run together
as a single mob ensuring similar feeding levels and parasite
challenge. Group 1 lambs achieved an average daily bodyweight gain
(ADG) of 161.7 g/day after moxidectin treatment and 135.4 g/day after
ivermectin treatment. Group 2 lambs achieved an ADG of 100.4 g/day
after ivermectin treatment and 222.6 g/day after moxidectin treatment.
These differences were highly statistically significant."
New Zealand Journal of Agricultural Research --
A comparison of production responses in lambs drenched with
moxidectin or ivermectin
http://www.rsnz.govt.nz/publish/nzjar/1995/88.php
On the other hand, an alpaca didn't do so well:
"A product containing moxidectin given subcutaneously to 60 alpacas
produced severe pulmonary oedema, 3-5 minutes post injection in one
animal with white froth passed from the nose and mouth. This animal
recovered gradually with treatment. The signs observed were consistent
with acute anaphylaxis which may occur sporadically with any
injectable product. Such a reaction is an infrequent and unpredictable
occurrence. "
Report of Adverse Experiences
http://www.nra.gov.au/qa/aer95.shtml
Information about the human trials is presented at:
TDR Drug Research
http://www.who.int/tdr/research/progress9900/tools/drug-onchofil.htm
My conclusion would be to use the drug in healthy, robust canines, but
be careful on debilitated animals.
Search Terms Used:
moxidectin ivermectin
warning moxidectin canine
It's been a pleasure researching your question. If you need anything
further, please feel free to ask for clarification (and I'd appreciate
your holding off on rating my answer until I have a chance to respond
to any request!)
Sincerely,
richard-ga |
