This presentation was prepared for the Blue Ribbon Sheep Forum in Storrs, CT (2/25/12).

1. SUSAN SCHOENIAN (Shāy-nē-ŭn)
Sheep & Goat Specialist
Western Maryland Research & Education Center
sschoen@umd.edu - www.sheepandgoat.com

2. Alt.
forages
Deworm Browsing
“Natural” Clean
anthelmintics pastures
Integrated
means
combining and
coordinating
Refugia
IPM Nutrition
diverse
elements Zero
grazing
Manage
-ment
into a whole.
Host
Genetics
Internet definition immunity
Grazing
Mgt.

3. Integrated pest management
(IPM) is a method of controlling CHEMICAL
parasites in a population of Deworm
animals by using a combination
of chemical and non-chemical
methods.
[Pfizer Animal Health]
INTEGRATED
NON-CHEMICAL
alternative forages;
browsing; clean pastures;
coccidiostats; delayed grazing;
FAMACHA©; Five Point Check©; genetic
selection; host resistance; low stocking rates; management; multispecies grazing;
“natural” anthelmintics; nutrition; pasture rest and rotation; grazing height; proper
anthelmintic use; protein supplementation; refugia; sanitation; and zero grazing.

4.  Though it varies by farm,
worms have developed
resistance to ALL of the
anthelmintics.
 It’s not sustainable (or
sometimes even possible)
to control internal parasites
with drugs alone.
 There is a growing interest
among producers and
consumers alike for more
natural methods of pest
control.

5. Pasture
Plants Animal
Soil Immunity
Behavior
Possible
clinical
disease
Parasite
Biology
Life cycle Weather
Temperature
Moisture

6.  A living organism
(generally
undesirable) that
exists by stealing
the resources
produced or
collected by
another living
organism.
[Wiktionary]
barber pole worms in abomasum

7. EXTERNAL (ECTO)
INTERNAL (ENDO)
 A parasite that lives inside  A parasite that lives on
another organism. the outside of the animal.
barber pole worm ticks, lice, mites, flies, etc.

8. There is a species from each kind that is especially problematic for sheep .
PROTOZOA
HELMINTHS Single-cell
Multi-cellular
 Coccidia
1. Nematodes  Giardia
Roundworms  Cryptospordium
2. Cestodes
Tapeworms
3. Trematodes
Flukes VS.

9.  Haemonchus contortus
Barber pole worm  Bunostomum
Hookworm
 Cooperia
Small intestinal worm
 Nematodirus
Threadneck worm
 Oesophagostomum
Nodule worm
 Strongyloides
common threadworm
 Trichostronylus  Trichuris ovis
hair or bankrupt worm
whipworm
 Telodorsagia (Ostertagia)
medium or brown stomach worm
 Lungworms
 Paralaphostrongylus tenius
Meningeal worm

10.  Most deadly.
 Found in abomasum
 Blood-sucker
 Short, direct life cycle
 Prolific egg producer
Barber pole worm
 Requires warmth and moisture Image source: Dr. Nabavi (Iran)
to complete its life cycle.
 Warm, moist climates
 Summer rainfalls
 As a mechanism of survival, can go into a hypobiotic (arrested) state.
 Is adapting to cooler climates  global climate change (?)

11. CLINICAL SIGNS
 Sudden death
Gradual weight loss
Weakness
Poor stamina
Diarrhea constipation
Anemia
FAMACHA© score 4 or 5
Sub-mandibular edema
“bottle jaw”
Death

12.  Same genus.
 Affect abomasum1
and small intestines2.
 Similar life cycle
as barber pole worm 
 Mixed infections with barber pole
worm are common.
 Cause reduced performance, ill-
thrift and dagginess (diarrhea),
occasionally death.
 Under the microscope, eggs look
the same as barber pole
worm eggs.

13.  Roundworm that normally
infects white tail deer,
but causes little problems.
 But causes severe neurological
disease when it infects an
abnormal host, such as a sheep.
 Has indirect life cycle with
terrestrial snails and slugs
serving as the intermediate hosts.
 10-14 days after ingestion of an infective snail or slug,
the parasite migrates to the spinal cord (central nervous
system) and begins causing damage to neurological tissue.
 Sheep are a dead end host. Must necropsy to confirm diagnosis.

14. CLINICAL SIGNS
 Variable and similar to other
neurological diseases, such as
polio, listeriosis, and rabies.
 Weakness
 Lameness
 Circling
 Blindness
 Head tilt
 Abnormal behavior
 Paralysis
 Death

15. TREATMENT -- early -- PREVENTION
 Exclude deer
 Repetitive, high doses of
anthelmintics [Rx]  Don’t graze in woods or near
 Ivermectin for 5 days ponds.
 Fenbendazole for 5 days
 Avoid grazing poorly-drained
 All anthelmintics have been pastures.
used to treat meningeal
worm infections.  Reduce snail, slug population.
 Anti-inflammatory drugs [Rx]  Preventative treatments with
anthelmintics
 Regular deworming will promote
 There is no scientific evidence development of anthelmintic-
that any of the various resistant GI worms.
treatment protocols are
effective.

16.  Indirect life cycle, with
pasture mites serving as the
intermediate host.
 Worm segments are visible in
feces (gross!).
 Generally non-pathogenic
(disease-causing).
 Generally no benefit to
treatment for tapeworms
alone.
 Can treat with fenbendazole
(SafeGuard®), albendazole
(Valbazen®, or praziquantel.

17.  Indirect life cycle, with Image source:
gastropods serving as the http://www.flickr.com/photos/peteredin/3386220058/
intermediate host.
 Can be found everyone, but are
mostly a problem in the Gulf
States and Pacific Northwest, i.e.
cool, wet climates.
 Clinical symptoms include
anemia, bottle jaw, and weight
loss.
 Liver flukes can’t be found in a
normal fecal egg flotation.
 Treat with albendazole
(Valbazen®) or Clorsulon [Rx].

18.  Single-cell, spore-
forming protozoan
parasite.
 Complicated life cycle
with many stages and
both sexual and asexual
reproduction
 Approximately 21 days
 10 species known to
infect sheep and goats.
 Not all are pathogenic
 Host-specific.

19.  Subclinical
(usually goes undetected - most costly)
 Poor performance
 Performance set-back
(even after treatment)
 Clinical
 Failure to thrive
 Ill-thrift
 Open-fleeced
 Dagginess
 Diarrhea
 Anorexia
 Anemia
 Dehydration
 Death

20. PREVENTION TREATMENT
 Coccidiostats in feed,  Drench with Corid
mineral, or water. (amprolium) or Sulfa drugs
 Bovatec® (lasalocid)
(Albon®, Di-methox) [Rx]
 Supportive therapy
 Deccox® (decoquinate)
 Rumensin® (monensin) [Rx]
 Corid (amprolium) [Rx]
 Good management
 Good sanitation
 Proper stocking rates
 Coccidiostats, especially Rumensin® can be toxic to horses and dogs.

21. FECAL EGG COUNTS (FEC) LARVAL ID
 To differentiate between  To differentiate between strongyle
strongyle (stomach) and (stomach) worms (H. contortus,
tapeworm eggs and coccidia Teladorsagia, and trichostrongyles)
oocytes. ▪ University of Georgia
▪ Other universities
 Can’t differentiate between
strongyle (stomach) worm
eggs except Nematodirus) LECTIN-STAINING TEST
1. Do-it-yourself  Determine percent of Haemonchus
2. Public lab contortus eggs in a fecal sample
3. Diagnostic lab
 Oregon State University
4. Private lab
 University of Georgia
5. Veterinarian

22.  Host immunity
 Management
 Clean or safe pastures
 Multi-species grazing
 Pasture rest and rotation
 Alternative forages
 Nutritional management
 Zero grazing
 Genetic selection
 Manage refugia
 Targeted selective
treatment

23.  Sheep have several
defense mechanisms
for dealing with
internal parasites:
1. Immune exclusion
2. Self-cure
3. Immunity
a) Innate
b) Acquired

24. IMMUNE EXCLUSION
SELF-CURE PHENOMENON
 Ingested larvae fail to
establish in heavily  Adult nematodes are
infected animals. spontaneously expelled
when there is a massive
larval invasion over a
very short exposure
period.
 Usually observed after
a heavy rain.
Why does it occur (?)
▪ Increase in
abomasal pH
▪ IgE mediated
hypersensitivity

25. St. Croix lambs
ACQUIRED
 Immunity that is not
inherited.
 Immunity that is acquired
INNATE (INBORN, NATURAL) during life.
 Immunity that results from
 Infection is limited during exposure to the disease.
the initial exposure.
 Immunity that occurs
naturally as part of an
individual’s genetic
make-up. Crossbred lambs

26.  Develops with advancing age
and parasite exposure.
 Not until >4 months of age,
depending upon breed and
nematode species.
 Preventative anthelmintic
treatments interfere with the
development of immunity.
 Adults are generally immune
to parasites, but under stress
can break down.
 Sheep have a weaker degree
of immunity than other
livestock, except for goats.

27.  Lasts for about 4 weeks
 May occur earlier (in
pregnancy) if ewes are
underfed or under stress.

Primary source of infection
for new crop of lambs.
 Cause (?) Hypothesis:
Lactation after pregnancy
 Increasing prolactin levels
 Reduction in IgA antibodies associated
with transfer of maternal antibodies in
colostrum

28.  If lambing occurs in the
spring, it will coincide
with the maturation
and egg production
from previously
arrested worm larvae.
 Management strategies
1. Deworm all ewes prior to
parturition with an
anthelmintic that is effective
against hypobiotic larvae.
2. Increase protein level of ration
during late gestation (by 30%).
3. Selective deworming using
FAMACHA© system and/or
Five Point Check©.

29. MORE SUSCEPTIBLE MORE RESISTANT
 Weaned lambs  Mature sheep
 Bummer lambs  Dry ewes
 Late-born lambs  Pet sheep
 Yearlings  Mature wethers
 High-producing females  Sheep in good body
 Periparturient ewe condition
 Thin animals  Fat sheep
 Geriatric sheep
 Unadapted breeds
 Stressed animals

30.  Good sanitation
 Use feeders
 Clean water
 Avoid overgrazing
 Do not graze below
2 inches.
 Time lambing to
minimize parasite
infections.

31.  Pasture rotation is a
recommended strategy for
controlling internal parasites
because it allows the use of
cleaner (rested) pastures.
 Intensive rotational grazing may
not help to reduce parasitism
unless rest periods are long
enough.
 Due to increased stocking rates,
management intensive grazing
may increase internal parasite
problems in sheep and lambs.
 It takes about 2 months of rest
for a contaminated pasture to
become relatively “clean” for
sheep grazing.

32.  A pasture that has not been grazed by
sheep (or goats) for the past 6 to 12
months.
 A pasture that has been grazed by
adult cattle and/or horses for the past
6 to 12 months.
 New pasture
 A pasture that has been renovated
with tillage.
 A pasture in which a hay or silage crop
has been removed.
 A pasture that has been rotated with
row crops.
 A pasture that has been burned.

33.  Livestock that browse have
fewer parasite problems.
 Livestock grazing tall-growing
forages will have less parasite
problems.
 80% of parasite larvae is found in
the first two inches of vegetative
growth.
 Grazing tanniferous forages may
reduce the effects of parasitism.
 Sericea lespedeza
 Chicory
 Birdsfoot trefoil

34.  Sheep and goats share the same
parasites, but they are different
from the parasites that affect
adult cattle and horses.
 Producers who graze multiple
species of livestock report fewer
parasite problems with small
ruminants.
 Cattle and horses “vacuum”
sheep/goat pastures of infective
worm larvae.
 Sheep, goats, and cattle have
complementary grazing habits.

35.  Animals on a high plane of nutrition
and in better body condition are
better able to withstand worm
burdens.
 Nutrition in early pregnancy (fat
stores) can affect the immune
response to internal parasites.
 Sheep receiving higher levels of
protein prior to lambing have lower
fecal egg counts.
 Supplementing grazing lambs with
protein has been shown to reduce
fecal egg counts.
 Nutritional supplementation is most
likely to be beneficial when pregnant
females and young animals are below
optimal body condition at a time
when pasture quality and/or quantity
is limited.

36.  Sheep raised in confinement
or dry lot (zero grazing) tend
to have fewer worm
problems.
 Sheep put in confinement or
dry lot do not usually get re-
infected with worms.
 Coccidiosis could still be a
problem, if preventative
measures are not taken.
 Good sanitation
 Proper feeders
 Coccidiostats

37.  Resistance
 Ability of host to
resist infection
 Measured by fecal
egg counts (FEC-EPG).
 Resilience
 Ability of host to withstand
challenge and/or infection.
 For barber pole worm:
measured by packed cell
volume (PCV) and
estimated by FAMACHA©
eye anemia scores.

38. St. Croix
 Breeds vary in their
resistance and resilience
to gastro-intestinal
parasites.
1. Hair sheep
(tropical or West
African origin)
2. Gulf Coast Native
3. Katahdin
4. Dorper
 Others (?)

39.  There is as much
difference within breeds
as between breeds.
 The 80-20 rule
Approximately 20 percent of
the flock sheds 80 percent of
the eggs onto pasture.
 Parasite resistance is are
moderately-heritable.
H2 = 0.22-0.63 (avg. 0.25)
 Selection for parasite
resistance will not adversely
affect the growth of lambs
or fertility of ewes.

40.  Do not deworm on a regular
schedule.
 Do not deworm all animals in a
group.
 Do not return treated animals to
a clean pasture.
 Give all anthelmintics orally at
the proper dose.
 Do not underdose.
 Deworm new animals with
anthelmintics from 2-3 different Without refugia, worms will eventually
chemical classes. be resistant to all anthelmintics.

41. Point What to check Which parasites
Paling of ocular
membranes Barber pole worm
1 Eye
FAMACHA© eye anemia Liver fluke
score
2 Back Body condition score All
Brown stomach worm
Dag score
Hair worm
3 Rear fecal soiling
Threadneck worm
evidence of scouring
Nodule worm
Sub-mandibular edema Barber pole worm
4 Jaw
(bottle jaw) Liver fluke
5 Nose Nasal discharge Nasal bots

42. Packed cell Treatment
Eye lid color
volume recommendation
1 Red > 28 Optimal No
2 Red-Pink 23-27 Acceptable No
3 Pink 18-22 Borderline ?
4 Pink-White 13-17 Dangerous Yes
5 White < 12 Fatal Yes

43. Transverse
Spine Muscle Fat
processes
Fingers easily pass
Individually clearly felt,
1 sharp, obvious
underneath Very little No
Form a smooth line with
2 deep undulations
Smooth round edges Concave Very thin
Well covered Not concave
Only slightly detectable
3 undulations
have to push firmly to
get fingers underneath Not convex
Moderate
Only detectable with firm
4 pressure Cannot be
Maximally Thick
developed
felt at all
5 Not detectable Convex Very thick

44. Treatment
Dag score Description
recommendation
0 No fecal soiling No indication for treatment
1 Very slight soiling on edge of tail No treatment
Slight soiling on edge of tail and on
2 each side
Usually no treatment
Moderate soiling of tail and wool
3 Dag formation
Consider treatment
Severe soiling extending far into wool Treatment, crutching
4 Severe dag formation recommended
Very severe Treatment and crutching
5 watery diarrhea extending to hocks essential

47.  Indicates “potential”
parasite burden in
animal.
 Indicates potential
parasite contamination.
 Use to determine level
of drug efficacy.
 Use to determine
genetic differences in
parasite resistance
among animals.

48.  Fecal egg counts are not
always well-correlated
with disease.
 Presence of eggs does not
mean that the animal is
clinically parasitized and
needs treatment.
 Absence of eggs or
oocytes (coccidia) does not
mean that the animal is
parasite-free and not in
need of treatment.

50. 1)Benzimidizoles
2)Nicotinic agonists
3)Macrocylic lactones

51. 1) Fenbendazole
SafeGuard®,
Panacur®
[Rx]
2) Albendazole
Valbazen®
3) Oxyfendazole
Synanthic®
[Rx]

52.  White dewormers
 Water soluble
 Broad spectrum
 Wide margin of safety
 Efficacy against
tapeworms
 Efficacy against adult liver
flukes (albendazole)
 Do not use albendazole
during first 30 days of
pregnancy or ram removal.
 Widespread resistance
 Resistance is caused by
dominant gene

53. 1) Imidazothiaoles (IMID)
a) Levamisole
Prohibit®, Levasol®
2) Tetrahydropyrimidines
(TETR)
a) Morantel [Rx]
Rumatel®
b) Pyrantel [Rx]
Strongid®

54.  Levamisole
 Clear drench
 Water soluble
 Broad spectrum of activity
 Not effective against
arrested larvae
 Narrower margin of safety
 Resistance reported
 Resistance is caused by a
recessive gene
 Morantel and Pyrantel
 Not effective against
larval stages of worms.

55. 1) Avermectins
a) Ivermectin
Ivomec®
b) Doramectin [Rx]
Dectomax®
2) Milbemycins
a) Moxidecin
Cydectin®
Quest® [Rx]

56.  Broad spectrum
 Wide margin of safety
 Effective against (biting)
external parasites
 Persistent activity
 Widespread resistance,
reported especially
ivermectin
 Resistance is caused by
dominant gene

57. 1) DRENCHRITE® 2) FECAL EGG COUNT
LARVAL DEVELOPMENT ASSAY REDUCTION TEST (FECRT)
 An in vitro test for the detection  Comparison of before and
of resistance to all anthelmintic after fecal egg counts
groups.
 Benzimidizoles
7 days post-treatment
 Need pooled fecal sample from 10
 Levamisole
or more animals (minimum of 6)
7 days post-treatment
at least > 350 epg
 Avermectins
>500 epg preferred
14 days post-treatment
▪ Animals with FAMACHA© scores of
3, 4, or 5 are more likely to have  Should include “control”
higher egg counts if barber pole
worm is the primary parasite. (untreated) animals in testing.

58.  Weigh animals to determine
proper dose.
 Do not underdose.
 Use proper drench technique.
 Fast animals prior to
treatment with ivermectin or
albendazole.
 Give multiple anthelmintics
 Synergetic effect
 Maximize refugia

59.  An anthelmintic acts to expel
or destroy parasitic worms.
 Using this definition, there
aren’t any consistently
effective “natural”
anthelmintics.
 An animal that is clinically
parasitized should be treated
with a “chemical” dewormer.
Haemonchosis

60.  They may not treat a
clinically-parasitized animal,
but they may reduce the
number of animals that
require treatment.
 Disruption of parasite
life cycle (on pasture)
▪ Eat larvae or eggs
▪ Inhibit larvae development
▪ Inhibit egg hatching
 Strengthening of the
immune system.
An increasing number of scientific studies are being conducted to identify compounds which
may have anthelmintic-like properties. Current claims are largely antidotal.

61.  Herbal dewormers
[oils and seeds]
 Artemisia genus (Wormword)
 Garlic Papaya
 Paprika Ginger
 Pumpkin Mustard
 Tanniferous forages
 Nematode-trapping fungus
 Copper oxide wire particles
 Copper sulfate
 Tobacco (nicotine sulfate)
Sericea lespedeza

62.  Zolvix® drench (Monepantel)
Amino-Acetonitrile (ADD) class
First new anthelmintic since
1980’s
 Unique mode of action
 Targets a receptor that
paralyzes the worm
 Effective against worms that are
resistant to other anthelmintics.
 Currently undergoing
testing in the U.S.
Approval for sheep, if/when [?]

63. Thank you for your
attention.
Any questions?
Susan Schoenian
sschoen@umd.edu
www.sheepandgoat.com