PARASITES AND GOATS
DAKOTA GOAT ASSOCIATION
STATE WIDE GOAT CONFERENCE - OCTOBER 20, 2017
Sheep & Goat Specialist
University of Maryland Extension
firstname.lastname@example.org - (301) 432-2767 x343
www.wormx.info - www.sheepandgoat.com
• American Consortium for Small Ruminant Parasite Control (ACSRPC)
• Biology of parasites
• Anthelmintics (dewormers) 101
• Anthelmintic resistance
• Combination treatments
• Copper oxide wire particles
• Nematode trapping fungus
• Fecal egg counting
AMERICAN CONSORTIUM FOR SMALL
RUMINANT PARASITE CONTROL
A group of scientists, veterinarians, and extension specialists devoted to (1) developing
novel methods for sustainable control of gastro-intestinal nematodes in small ruminants
and (2) educating the stakeholders in the small ruminant industry on the most up-to-date
methods and recommendations for control of gastrointestinal nematodes.
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AFFECTING SMALL RUMINANTS
OVERVIEW OF PROBLEM
• Gastro-intestinal parasites are the primary
health problem affecting sheep and goats
• GI parasites can be an obstacle to
profitable and sustainable small ruminant
production in many climates and
• Small ruminants are more susceptible to
parasitism than other farm livestock
• Goats are more susceptible than sheep.
• Problem is worsened by drug resistance.
GOATS AND PARASITES
WHY ARE THEY SO SUSCEPTIBLE?
• Goats are browsers or intermediate grazers.
• They rely on feeding strategies to avoid
ingestion of infective worm larvae, which are
found mostly in first two inches of vegetative
• Unlike sheep, goats are unable to reduce
establishment of infective worm larvae or to
expel adult worms.
• In goats, immunity is rarely completely effective
• Exposure to worms is necessary to develop
immunity; low levels are insufficient.
GOATS CAN HOST MANY DIFFERENT
KINDS OF INTERNAL PARASITES.
1. Haemonchus contortus
Barber pole worm
2. Trichostrongylus spp.
Black scour worm (bankrupt
3. Teladorsagia (Ostertagia)
Brown stomach worm
NEMATODES – ROUNDWORMS - STRONGYLES
5. Trichuris ovis
• Haemonchus contortus
Barber pole worm
• Trichostrongylus spp.
Black scour worm
• Teladorsagia (Ostertagia)
Brown stomach worm
Eggs look the same; need to hatch larvae in order to differentiate species.
Trichostrongylus/Teladorsagia are often not differentiated even when doing larvae ID.
ROUNDWORMS CAN BE
HARD TO CONTROL
• Short, direct life cycles
• No intermediate host
• Ability to engage in hypobiosis
• Barber pole worm is prolific egg layer
• Goats slow to develop immunity.
• Compromised immunity of peri-
• Widespread and growing drug
L4 larvae in “arrested
During winter, most
larvae are in “arrested
prolonged cold. This
allows worms to
survive over winter (as
hypobiotic larvae) and
Hypobiotic larvae is
the primary means by
which worms survive
in a northern climate.
PERI-PARTURIENT EGG RISE (PPER)
• Loss of immunity during late gestation
and early lactation; occurs from several
weeks before to several weeks after
• Well-documented phenomenon in
sheep; also documented in goats.
• With spring kidding, PPER often
coincides with hypobiotic larvae
resuming their life cycle.
• Need to have a strategy for dealing with
periparutient egg rise.
• Primary source of pasture
COCCIDIA (EIMERIA SPP.)
THE OTHER BIG PARASITE PROBLEM
• Single-cell protozoan parasite.
• Has more complex life cycle than roundworms.
• Not all species are pathogenic (harmful).
• Affects lambs/kids mostly before and after
• Sheep develop strong and lifetime immunity;
goats probably less so.
• Causes diarrhea, but not always, and general ill-
• Associated with poor hygiene and management.
• Good hygiene, nutrition, and
• Coccidiostats in mineral, feed, or water
Need to feed or put in water before risk period
1. Lasalocid (Bovatec®) - sheep
2. Monensin (Rumensin®) - goats ( horses)
3. Decoquinate (Deccox®) - both
4. Amprolium (Corid®) - ELDU, OTC
• Natural control
• Sericea lespedeza pellets
• Other (?)
• Amprolium (Corid®)- ELDU, OTC
• Sulfa drugs (Di-Methox®) - ELDU, Rx, VFD
Damages lining of small intestines.
Damage can be permanent (“runts”)
WHAT ABOUT TAPEWORMS?
• Tapeworms are the only parasite visible in the
feces. Diagnosed by seeing segments in
• Tapeworms tend to be non-pathogenic; not
harmful, but they’re blamed for a lot, usually
no benefit to treatment (goats?).
• Lambs develop immunity at very young age.
• Tapeworms can cause mild unthriftiness and
digestive disturbances, intestinal blockages
(rare) and affect gut motility, predisposing
lambs to enterotoxemia (occasionally).
• Treat with albendazole (Valbazen®) or
praziquantel (in some horse dewormers,
WHAT ABOUT MENINGEAL WORM?
• Parasite of white tail deer.
• Also called deer or brain worm.
• Sheep, goats, alpacas, and llamas are
all abnormal hosts.
• Infection requires an intermediate host,
terrestrial snail or slug.
• Causes various neurological symptoms.
• No diagnostic test in live animal.
• No FDA-approved or proven treatment.
• Cornell University has been evaluating
treatment protocols: fenbendazole
(SafeGuard®) + anti-inflammatory drugs
(Dexamethasone or Banamine).
WHAT IS AN ANTHELMINTIC?
• Compound used to kill gastro-intestinal
parasites (worms) without harming host.
• More commonly called wormer, dewormer or
• Anthelmintics have different chemistries.
• Chemistry determines which worms they are
effective against, mode of action, and withdrawal
• Anthelmintics are grouped by chemistries.
• There is cross-resistant among drugs in the
same groups, having the same modes of action.
THERE ARE THREE (SORT OF 4) “CHEMICAL”
CLASSES OF DEWORMERS FOR SMALL
RUMINANTS (IN THE US).
Macrocylic lactones (ML)
Avermectins Milbemycins Imidazo-thiazoles Tetrahydro-pyrimidines
ANTHELMINTICS FDA-APPROVED FOR GOATS
Adult worms Not approved
Larvae (L4) Not approved sporadic
Hypobiotic larvae Not approved
Lungworms Not approved
Tapeworms Not labeled Not approved
Liver flukes Adult stage
Safety wide 10x (sheep)
Dosage 1.2 ml/50 lbs. 4 ml/100 lbs. Varies by product
Meat withdrawal 6 days 7 days 30 days
Milk withdrawal 0 days
EXTRA-LABEL ANTHELMINTICS FOR GOATS
Cydectin® sheep drench
Larvae (L4) Limited
Hypobiotic larvae Limited
Tapeworms Double dosage
Liver flukes Adult stage
External parasites Some
label for bot control
Safety wide 10x
20x 5x 3x
Dosage 1.1 ml/25 lbs. 2 ml/25 lbs. 6 ml/25 lbs. 4.5 ml/25 lbs. Depends on
Meat withdrawal 16 days
(1 day for each additional day used)
9 days 14 days 17 days 4 days
Milk withdrawal 4 days
(1 day for each additional day used)
7 days 9 days 8 days 3 days
• Worms develop resistance to drugs.
Can’t be killed!
Pass resistant genes onto next
• Some animals are more resistant to
Ability to reduce parasite establishment.
Pass resistance genes onto next
TWO KINDS OF RESISTANCE WHEN WE
TALK ABOUT INTERNAL PARASITES
WHAT IS ANTHELMINTIC
• Genetic ability of a worm to survive a dose of
anthelmintic which would normally be
• Only worms that survive treatment carry
genes that confer resistance.
• Result of selection through exposure of worm
population to an anthelmintic.
• When more than 5 percent of worms are
“drug tolerant”; i.e. failure to reduce FEC by
95% or more (some say 90%).
• In the US, worms have developed resistance to
all dewormers and dewormer classes, though it
varies by geographic region and farm.
• Worse in Southeast due to increased parasite risk
and need for deworming.
• Worse on farms that frequently deworm or use
improper deworming practices.
• Most farms have resistance to at least two
dewormers; some farms have resistance to all
Benzimidazoles Ivermectin Levamisole Moxidectin
Maryland Virginia Georgia
WHAT ABOUT RESISTANCE IN MORE
A 16 77
B 70 41
C 38 78
D 0 0
• There is growing suspicion
that the geographic range of
the barber pole worm is increasing
and that resistance to deworming
agents is on the rise.
• A pilot project in Alberta (2015)
showed that many Alberta sheep
flocks have high parasite burdens
and that ivermectin and fenbendazole
-resistant parasites may be common
in the province.
• NCAT is working with Montana State University Extension to determine
anthelmintic resistance in Montana, Wyoming, and Utah.
ANTHELMINTIC RESISTANCE IS
INEVITABLE, BUT CAN BE DELAYED.
Practices that accelerate development of resistant worms
1. Frequent deworming
2. Whole flock treatments
3. Calendar based treatments
4. Treat and move strategy
5. Rotating dewormers
7. Depositing drug in mouth instead of deep into oral cavity.
8. Use of persistent activity dewormers
9. Use injectable dewormers
10.Use pour-on dewormers.
11.Use of feed dewormers*
12.Improper storage of dewormers
FECAL EGG COUNT
• Compare before and after fecal egg counts
from same animals.
• Old protocol compared post-treatment FECs of
treated animals vs. control (untreated) group.
• ~15 animals per drug tested
• Minimum FEC of 250 epg*, preferably higher.
• Can use individual or pooled (composite)
• Cost varies. Can learn to do yourself or send to
• Labor-intensive laboratory test that
determines resistance to all dewormers
and classes from a single pooled fecal
sample (from ~10 animals).
• Minimum FEC of 500 epg.
• Also identifies larvae: % Haemonchus
Trichostrongyles eggs look the same.
• Test done exclusively by Dr. Ray Kaplan’s
lab at the University of Georgia.
• $450 per sample
TWO WAYS TO TEST FOR
Different drugs to kills same parasites.
Not different drugs for different parasites.
“THERE NOW IS VERY STRONG
EVIDENCE THAT USING COMBINATION
TREATMENT IS THE BEST METHOD FOR
USING DEWORMERS AND SHOULD BE
INSTITUTED ON ALL FARMS
DR. RAY KAPLAN, UNIVERSITY OF GEORGIA (JANUARY
• Most farms have resistance to at
least two of the three major groups of
dewormers; some have resistance to
• At first introduction, drug efficacy is over
• Once efficacy falls below 95%, drug
resistance is present, though drug is still
useful for treatment.
• As effectiveness of dewormer decreases
(<95%), as it is used more, it provides less
and less benefit to animals.
• Below 50%, it is no longer effective as sole
There is already resistance to Zolvix® in
other countries. Zolvix® is not sold in US.
WHY GIVE COMBINATION
• Contrary to popular belief, rotating between
dewormers will not prevent resistance from
developing. In fact, it will allow worms to develop
resistance to multiple drugs simultaneously. It is
no longer recommended.
• Research done in New Zealand has shown that
the best approach is to use several different
dewormers at one time as a combination
• When combined with “best management
practices” (that help to maintain refugia),
combination treatments may improve drug
efficacy and result in a reversion back toward
Most dewormers sold in New Zealand and Australia
are combination products (multiple drug actives in
same product); combination products are not
available in US.
HOW DO COMBINATIONS WORK?
• Unlike rotating drugs, there is an
additive effect with each drug used
in a combination treatment.
• By achieving a higher efficacy,
there are fewer resistant worms
that survive treatment.
• The sooner you start using
combination treatments the better,
as you achieve the greatest
difference in the percentage of
resistant survivors when efficacy of
dewormers is high.
Drug 1 Drug 2 Drug 3 Combo12 Combo123
80% 80% 80% 96.00% 99.20%
90% 90% 90% 99.00% 99.90%
60% 95% 98.00% 98.00%
60% 60% 95% 84.00% 99.20%
99% 99% 99.99% 99.99%
60% 60% 60% 84.00% 93.60%
50% 50% 50% 75.00% 87.50%
40% 40% 40% 64.00% 78.40%
95% 80% 20% 99.00% 99.20%
RECOMMENDATIONS FOR USING
• Purchase and administer each dewormer separately in a
• Do not mix dewormers. They are not chemically
compatible. Only veterinarians have the right to compound
• Administer each dewormer at full dose based on an
• Can give one drug immediately after the other.
• Observe withdrawal period of drug with longest withdrawal
RECOMMENDATIONS FOR USING
DEWORMERS IN COMBINATION
Valbazen® Cydectin® Prohibit®*
Goats 4 ml/50 lbs.
[9 days meat]
[7 days milk]
9 ml/50 lbs.
[17 days meat]
[8 days milk]
Depends on dilution
[4 days meat]
[3 days milk]
WHAT ARE COPPER OXIDE WIRE
• Tiny metal rods of copper oxide
• Poorly absorbed, slow release form of
copper versus copper sulfate which is
very absorbable; therefore, greater
potential for toxicity (especially in
• Has been shown to reduce barber pole
worm infections in sheep and goats.
• Available as copper supplement
(different brands) for cattle (12.5 and
25 g) and goats (2 and 4 g). https://www.wormx.info/copper-oxide-wire-particles
• Goats require more copper than sheep in their
diets and are less susceptible to copper toxicity.
• Copper metabolism is very complicated, with
several antagonists (interactions), including
molybdenum, sulfur, zinc, cadmium, and iron.
• Copper absorption is more important than copper
concentration in diet.
• Copper requirements have been set at 15, 20, and
25 ppm for lactating, mature, and growing goats
respectively [NRC, 2007].
• The maximum tolerable amount is unknown for
YOU CAN ASSESS THE
COPPER STATUS OF
• Copper toxicity is less likely in goats, but it
can occur, as can a copper deficiency.
• Blood copper levels can be misleading
• Excess copper accumulates in liver.
• Collect liver and kidney samples for
• Frozen or chilled samples can be sent to
Michigan State University for testing.
NEMATODE TRAPPING FUNGUS
• Duddingtonia flagrans is a
nematophagous fungus, meaning that it
traps, paralyzes, and consumes
• Non-chemical, biological control of the
free-living stage of nematode parasites.
• Substantially reduces number of infective
worm larvae, including multi-resistant
• Is fed to grazing animals. Spores resist
digestion. No effect on host animal.
Passes through into manure.
• Reduces amount of reinfection from
contaminated pasture. Interrupts of life
USING FUNGUS TO CONTROL PARASITES
• Not commercially available. Not yet.
• Dr. Jim Miller from Louisiana State
University (retired) has been told that
product (fungus) should be available
sometime early 2018.
• Will need to feed every day to maintain
• Cost may be issue.
• Greatest application is probably zoo
• Positive or negative. Yes or no. - or +
• Mix feces with flotation solution.
Place cover slip on meniscus. Put on
• Estimates number of eggs in a fresh sample
of manure: eggs per gram of feces (EPG).
• Mix known amount of feces (2-4 g) with
known amount of flotation solution (26-28
• Fill chambers of McMaster slide.
FECAL EGG COUNTS (FECS)
• You can learn to do your own
fecals or send sample to a
• Microscope (100x)
Mechanical stage helpful
• McMaster egg counting slide
• Homemade flotation solution
THREE PRIMARY USES OF
FECAL EGG COUNTS
1. Determine treatment efficacy by comparing before and
after fecal egg counts from a group of animals (~n=15)
• Determine drug resistance on your farm
• Determine efficacy of alternative treatment(s)
2. Monitor pasture contamination
• How fast is pasture contamination building up?
• Determine when to move animals
3. Identify resistant and susceptible animals
• Differentiate between resistance and resilience
• Need sufficient parasite challenge to get data separation (at
least 500 epg group average, 1000 epg better)
counts are not
S H E E P & G O AT S P E C I A L I S T
U N I V E R S I T Y O F M A RY L A N D E X T E N S I O N
S S C H O E N @ U M D . E D U – ( 3 0 1 ) 4 3 2 - 2 7 6 7
X 3 4 3
S H E E PA N D G O AT. C O M – W O R M X . I N F O
Thank you for your attention.