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Part 5
of Series
Part
1
Parasite Control for Goats: Meet the Enemy
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Part 2
Managing the Barberpole Worm
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Part 3 Integrated Parasite
Management With
FAMACHA
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Part 4
Dewormers and Dewormer Resistance
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Part 6 Doing Your Own Research and Fecal Egg
Counts
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There has been a
great increase in interest in alternative
dewormers ie. substances used to control worms
which are not commercially available drugs or
pharmaceuticals. This has been especially true
with the continued development of dewormer
resistance by worms. Sometimes these are called
non-chemical dewormers, but also would include
organic dewormers, herbal dewormers, and natural
dewormers. Specific substances to be discussed
include tannins (including sericea lespedeza),
copper oxide wire particles, diatomaceous earth
and herbal preparations. There is some
significant scientific data on the several
alternative dewormers, but data on herbal
dewormers is scarce. The SCSRPC has coordinated
research on sericea lespedeza and copper oxide
wire particles and accumulated data from several
trials. One characteristic of many alternative
dewormers is not only the lack of data, but also
the lack of consistent data when data is
available. For example, in the study of copper
oxide wire particles in sheep, the copper oxide
wire particles were fairly effective in sheep in
all locations, but data in goats were not as
consistent, in fact, in three trials at one
location, they had little effect, but were
effective in a number of studies conducted in
three other locations. Alternative dewormers
need to be studied at several locations, with
sheep and goats and with different classes of
animals ie. kids vs. yearlings vs. mature does.
There is not much money available to fund this
kind of research which is why we have so little
data and understanding of these alternative
dewormers. There is a USDA funded study on
herbal dewormers for sheep and goats at Lincoln
Univesity in Missouri that is progressing. In
addition, when one gets into the many different
combinations of herbal dewormers that can be
used, the research becomes too large to be
accomplished. Hearsay data is not very good and
in some cases, very few animals were tested. In
the next article in this series, we will discuss
how to do your own research to see if the
dewormer (alternative or conventional) that you
use is working in your animals.
Tannins
Condensed tannins
have been shown to suppress fecal egg counts and
reduce worms in the digestive tract. Tannins
are a large group of polyphenolic compounds that
differ in many physical characteristics. Some
tannins such as in sericea lespedeza and other
plants have been shown effective in suppressing
worms whereas tannins in oaks and other plants
do not appear to possess those
characteristics. There is an excellent summary
of research on sericea lespedeza for worm
control by ATTRA (Tools for Managing Internal
Parasites in Small Ruminants: Sericea lespedeza,
http://www.attra.org/attra-pub/sericea_lespedeza.html).
Some work has been done overseas with sainfoin,
birdsfoot trefoil, dock and chicory
(tannin-containing plants that grow in the US)
showing that they too effectively suppress
worms. There are several studies that have been
done overseas with tannin containing plants,
most of which do not grow here or have a very
limited area of adaptation (Sulla, big trefoil).
One study showed that the tannins in some types
of browse are effective in suppressing worms.
Goat Eating Sericea Lespedeza
Even as much
research as has been done on sericea lespedeza
here in the US, there is so much that we don’t
understand other than it works both as fresh
forage and as a dried product (hay, meal,
pellets). Feeding in the short term reduces
fecal egg counts by half, and longer term
feeding appears to kill a portion of the worms
in the animal. In addition, fecal egg hatch may
be reduced and larval development and motility
affected. When goats are grazed on a solid
stand of lespedeza or a mixed lespedeza stand
(goats do have a strong preference for sericea
lespedeza in the middle of summer) and under
both scenarios, worm control was such that
dewormers were not needed, even in kids. When
animals were grazed on alternate weeks on
sericea lespedeza, there was a significant
reduction in fecal egg counts, but not as much
as for animals grazing sericea lespedeza
alone. We do not know if a pasture containing
20% sericea lespedeza will help suppress worms.
Can we supplement with sericea lespedeza hay to
animals for 10 days each month (or some such
scenario) and get a useful reduction in fecal
egg counts? There appear to be some differences
in potency of some improved varieties of sericea
lespedeza. To summarize, we know that sericea
lespedeza works (we assume it is tannins in the
plant), but we need to figure out more ways to
apply that knowledge to our goat production
systems.
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Tannin containing plants may work several ways
to reduce fecal egg counts. They have a high
level of protein and the protein and tannins
interact to improve protein nutrition of
animals. Protein supplementation has been shown
to suppress fecal egg counts in sheep and goats
most likely due to stimulation of the immune
system and tannin containing plants may work in
this way. Also, these plants grow high off the
ground and animals grazing these plants should
pick up fewer infective larvae which are on the
lower two to three inches of the plant. There is
some research that shows that tannins may bind
to the cuticle “skin” of worms and cause damage
to it. There are many other proposed mechanisms
by which tannins may work, but the important
thing is that we have identified some
tannin-containing plants that do suppress worms
and we can develop this knowledge into
application. In addition, there is potential
that we may identify other tannin containing
plants that suppress worms.
There are a
number of varieties of annual lespedezas which
were formerly thought to not have tannins, but
this needs to be reexamined as we now have
better tests for tannins. These plants may be
helpful for parasite control even if they are
proved to not have tannins since they have high
levels of protein and tend to grow high off the
ground. There are also native lespedezas which
grew in the tallgrass prairie and generally rare
now on most native range sites. These plants
could be useful since some have proven to have
tannins.
Copper Oxide Wire
Particles
Copper sulfate
was found to be effective in controlling the
Barberpole worm in the early 1900's and has been
used in many deworming solutions since. One
drawback was that it typically required 100 cc
of solution since copper sulfate is caustic and
must be made up in a dilute solution. Copper
oxide wire particles (COWP) were developed as a
slow release form of copper to treat copper
deficiency in Australia and New Zealand. One
researcher working with COWP to supply copper
observed a reduction in symptoms of worms in the
treated animals and in 1990 some New Zealand
researchers studied the effect of copper oxide
wire capsules on worms. They observed that COWP
were effective at removing only the Barberpole
worm. Since our major worm during the summer in
the Southeast U.S. is the Barberpole worm, COWP
should be effective as a dewormer at this time
of year. There have been a number of studies
conducted in both sheep and goats in the US in
recent years and there is a good summary written
by ATTRA (Tools for Managing Internal Parasites
in Small Ruminants: Copper Wire Particles at
http://www.attra.org/attra-pub/copper_wire.html).
The work is very
clear for sheep; administration of 1-2 grams
COWP in a gelatin capsule for ewes or 1.0 g for
lambs will reduce fecal egg counts 50-90% and
seems to be more effective in growing animals.
One must be careful with repeated use of COWP in
sheep due to the potential for copper toxicity.
However, COWP administration was repeated 4
times during the summer without toxicity. COWP
is an effective dewormer for sheep when the
Barberpole worm is the predominant species and
details on its use in the ATTRA publication
listed above.
COWP have been
shown to be effective in goats although in three
studies at one location it did not appear to be
effective because the Barberpole worm was not
the primary worm.. However at other locations
and multiple studies, COWP was an effective
dewormer in goats. Since goats are more
tolerant of copper, there is less concern about
repeated use of the COWP capsules than for
sheep. Basically, doses of COWP from 0.5 to 2.0
g appeared useful in reducing fecal egg counts
from 50-80% in goats and appeared to be more
effective in kids than in adults. A recent
study on pregnant goats shows promise for the
use of COWP incorporated in the feed (fed only
once) to reduce fecal egg counts. For details
on the use of COWP as a dewormer, refer to the
above ATTRA publication.
Trace Mineral
Bolus
There have been
two experiments at one location using a slow
dissolving trace mineral bolus (Small-Trace for
sheep, Agrimin Ltd., not available in the U.S.)
as a treatment for worms in adult goats. In one
experiment, there was a 75% reduction in fecal
egg count and in the other study, there was over
50% reduction in fecal egg count. This was
thought to be an effect of the copper oxide in
the bolus. The bolus seemed to have some
beneficial effects in reducing reinfection for
4-6 weeks. Research remains to be done in
sheep. The high level of copper may limit the
capsule to being used once during the worm
season with sheep.
Copper sulfate
was used for deworming sheep before dewormer
drugs were available. Copper sulfate was
recommended for control of stomach worms (Barberpole
worm) in sheep with 100 cc of a 1 % solution
being given to a yearling or adult sheep and
half that amount to a 3 month old lamb (USDA
Farmers Bulletin 1330, 1925; there are several
revisions of this bulletin). For tapeworms,
they recommended 1% copper sulfate with 1% of
snuff or powdered tobacco. The tobacco was
steeped in water overnight and the copper
sulfate added . The dose was 50cc for lambs and
twice this amount for a full grown sheep. Other
state experiment station bulletins recommended
copper sulfate treatment for worms in sheep,
often after an overnight fast. Studies at one
location showed that 1 1/2% copper sulfate was
effective at controlling the Barberpole worm in
sheep (AVMA 43:163, 1937). A more recent study
(2008) showed that a copper sulfate drench
(following fasting ) caused a 60% fecal egg
count reduction in ewes that had just been
weaned. However, in another study where copper
sulfate was incorporated in the feed for one
day, it was not effective as a dewormer.
Repeated use of copper sulfate has potential to
cause copper toxicity in sheep although some
reports indicated its use on a monthly basis for
a year. Higher concentrations of copper sulfate
in the drench (than 1.5%) are caustic. One
source reported success with feeding a 3.3%
mixture of copper sulfate in the salt which
appeared promising for several months until
sheep died from copper toxicity. When they
reduced the concentration in the salt to 2%., it
was ineffective at controlling worms. More
research is needed on copper sulfate.
Tobacco and
Nicotine Sulfate
Tobacco and
nicotine sulfate have been recommended in old
USDA and State Experiment Station Bulletins for
control of parasites. Data and dose are
sometimes sketchy in older literature as are
quantitative results. It was recommended for
control of intestinal worms (bankrupt worm and
brown stomach worm). It must be remembered that
nicotine sulfate is a nerve paralyzing toxin
with which one hopes to use enough of the drug
to paralyze the worm (causing him to turn loose
and go out the digestive tract) without using
too much, paralyzing (and killing) the animal.
The margin of safety between an effective dose
and killing the animal is not very wide, so one
must be very careful when using this chemical as
a dewormer. Most workers used 1-1.5% solution
of 40% nicotine sulfate with 100 cc being given
to a yearling or adult sheep and half that
amount to a 3 month old lamb. It was often used
in a mixture with copper sulfate (see above).
It must be emphasized that using these compounds
can be toxic to the sheep/goat. If you insist
on experimenting with copper sulfate and/or
nicotine sulfate, use them with a few cull
animals that you won’t mind losing if you do
have a problem with toxicity.
Diatomaceous
Earth
Diatomaceous
earth is fossilized unicellular marine or fresh
water algae called diatoms. It is used as a
food ingredient (read the labels on processed
foods) and in swimming pool filters. There are
cautions about using the swimming pool grade for
feeding animals in that it can be contaminated
with heavy metals whereas the food grade must be
proven to have non toxic levels of heavy
metals. Diatomaceous earth has been used for
many years for control of various pests from
grain weevils to houseflies. Goat producers
that use it for deworming control often mix it
with the mineral supplement or in the feed.
Most claims are that it extends the time between
dewormings although some claim that it kills
worms in goats. There have been 4 or 5
scientific studies and the data consistently
show that diatomaceous earth does not kill worms
in goats although one study did show that at a
very high level (5% of the diet), it had a
slight effect. There is speculation that it may
help fecal pellets to dry out faster which could
reduce the success of eggs developing into
infective L3 larvae. Research conducted on this
aspect has not been conclusive. It is very
difficult to study the claim that diatomaceous
earth increases the time between dewormings.
Herbal Dewormers
A problem with
herbal dewormers is that active ingredients may
vary with the stage of maturity, environment
(including soil that it is grown in, fertility,
moisture and daylength pattern), processing
and/or extraction procedure and variety of
plant. If you look at herbal supplements in the
pharmacy, the FDA has required manufacturers to
standardize the products based on a major active
ingredient i.e. Garlic is standardized based on
concentration of allicin, a bioactive ingredient
in garlic. When you buy dried cooking garlic
for deworming sheep or goats, you have little
idea of the concentration of allicin in it.
This is the problem for other herbals because
the active ingredient may be so low it is nearly
zero in one plant material source and another
source of plant material may contain higher than
average level of active ingredient. Another
problem is that common names do not always refer
to the same plant. For example, wormwoods refer
to plants of the genus Artimesia which includes
several species, some of which have a very high
level of artimesinin and some which do not have
artimesinin and in one study, the efficacy of
artimesia as a dewormer did not relate to its
active ingredient artimesinin ie. some other
substance must have been active in the plant.
Therefore, when working with herbals, there may
be inconsistencies in results for many reasons.
The only way to prove a dewormer (alternative
substance or pharmaceutical) is working for you
is to do a fecal egg count before using the
dewormer and 1-2 weeks after deworming on a
half dozen or more animals. It may be possible
for a consortium of producers to collect data
and help identify herbs or herbal combinations
which most commonly have an effect and these may
be worth more in-depth research. There has been
a good study on herbal dewormers conducted in
Pakistan which reviewed 232 studies on
bioactivity of plants on helminths (from
tapeworms to liver flukes and everything in
between). They identified 32 plants for
evaluation of their effectiveness as dewormers
based on literature and local information from
farmers and those providing veterinary
services. They did a tremendous amount of
research and identified 6 herbs with significant
dewormer activity, most of which do not grow in
the US or have a very limited distribution in
the US. They also found that alcoholic extracts
of the plants tended to be more effective than
feeding the plant (or plant part) itself.
Similar research needs to be done in the US, but
the research required tremendous inputs of time
and money.
Various herbs
have been used as dewormers, including garlic,
ginger, wormwoods, tansy, papaya seeds, pumpkin
seeds, extracts of black walnut hulls etc. You
can find many recommendations on various goat
listservers and web sites, some written articles
and word of mouth. There are even a few
commercial herbal preparations available from
various goat suppliers or on the internet.
Caution, some herbs can be toxic if consumed at
high levels! There are a few published
scientific studies in recent years on herbal
dewormers in goats. In one study, the herbal
dewormer, composition not given and different
combinations of herbs were used in different
years and it appeared to have been fairly
effective. One study showed that a wormwood
native to the US (present in all states but
Florida and Alabama) reduced fecal egg count by
50% after feeding a pound of air dried material
a day for 4 days. There is another published
study showed that a commercial herbal
preparation failed to control worms in sheep.
Another study indicated that herbal dewormers
were not very effective (http://nodpa.com/newsletters/NODPANewsFinal_March08_Proof.pdf
(Page 16). There are several unpublished
studies that failed to see a positive response
to garlic. Many producers swear by garlic and
other herbs, but good nutrition and management
also have an effect. One producer used a
product for 5 years and never lost a goat to
worms until they had a dry year and the goats
ran out of browse and were forced to graze the
grass to the ground resulting in severe goat
losses. They had to use conventional dewormers
to rescue the remaining animals. Their
management was preventing worm problems and not
their product. There is much that we don’t
understand about herbal dewormers and therefore,
one should not be surprised about different
people reporting different results. Remember
also that those who have less than positive
results are not as vocal as those who have
positive results.
Fungus
One promising
alternative treatment is nematophagus fungus, a
fungus normally present in the feces at a low
level which parasitizes some of the developing
worm larvae in the fecal pellet. There has been
some promising research with feeding spores of
this fungus to goats and sheep to increase the
number of these fungi in the feces. The higher
level of fungus in the fecal pellet kills most
of the larvae in the pellet. Since animals have
fewer infective larvae to pick up, the need for
deworming is reduced or eliminated. There are
currently two problems with the technology 1)
the fungal spores must be fed every day, less
frequent feeding will not work. 2) lack of a
commercial source of spores. Hopefully some
commercial company will develop an extended
release bolus that would release spores for 90
days. There was a company in Denmark providing
fungal spores for research, hoping to develop a
product, but their parent company has been
bought out and there is no longer a source of
spores. Research is being conducted in
Australia and India on the spores, so hopefully,
in the future these studies will culminate in
the development of a commercial product.
In conclusion,
there are some alternative dewormers that have
significant research data to show they work,
some may have limited data that merits further
studies, but many of them are very lacking in
data. If you choose to use these products, you
need to monitor the animals closely for worms,
using FAMACHA as a minimum and fecal egg counts
are even better, since these products may or may
not work. Also, one has to be aware of toxicity
potential of some alternative dewormers.
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