The document provides information about parasites that affect small ruminants like sheep and goats. It discusses the different types of internal and external parasites, including nematodes, cestodes, trematodes, and protozoa. It describes the lifecycles and signs of various parasites like barber pole worms, lungworms, tapeworms, and coccidia. It emphasizes that effective parasite control requires an integrated approach considering the animal, parasite, and pasture, and focuses on treatment in response to infection levels rather than routine preventative deworming.

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CRITICAL THINKING IN ANIMAL SCIENCE
Species: small ruminants
Topic: parasite control
SUSAN SCHOENIAN
Extension Sheep & Goat Specialist
Western Maryland Research & Education Center
University of Maryland Extension
sschoen@umd.edu - www.sheepandgoat.com
WESTERN MARYLAND RESEARCH & EDUCATION CENTER
Keedysville
Washington County
491 acres
Three units
University of Maryland
Extension
1. Administrative home for
West region
2. Extension specialists
3. Ag experiment station
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WESTERN MARYLAND RESEARCH & EDUCATION CENTER
Research Education (Extension)
Agronomy Ag marketing
Forages Farm management
Fruit Grapes and viticulture
Horticulture Forestry/natural resources
Small ruminants Nutrient management
Viticutlure/enology Small ruminants
WESTERN MARYLAND PASTURE-BASED
MEAT GOAT PERFORMANCE TEST
Established in 2006 to evaluate
the performance of meat goats
consuming a pasture-only diet
with natural exposure to gastro-
intestinal parasites.
Up to 70 weanling male meat
goats are tested per year.
While on test, goats are
evaluated for growth, parasite
resistance (fecal egg counts) and
parasite resilience (eye anemia
scores and need for anthelmintic
treatment).
Early June – early October
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CLASSIFICATION OF FARM ANIMALS
By their digestive systems
Monogastric
Simple stomach
Pigs and poultry (and people)
Ruminant
Cud-chewing
4 compartment stomach.
- Cows, sheep, and goats
Pseudo-ruminant
(3 compartment stomach)
- Alpacas and llamas
Hind-gut fermenter
Fermentation occurs in the caecum and/or
large intestine
Horses and rabbits
SMALL RUMINANTS
Sheep
Goats
Cervids (deer)
Camelids (alpacas and llamas)
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SHEEP AND GOAT PRODUCTION
Meat
Lamb/mutton
Chevon/cabrito
Fiber
Wool
Mohair
Cashmere
Dairy
Milk
Cheese
Other
Landscape management
Goats – shrubs, trees, browse
Sheep – weeds, grass
Bio-medical/tech
Research models
Blood
Pharmaceutical production
SHEEP AND GOAT PRODUCTION
World
1.93 billion sheep and goats
China, Australia, India
6 percent of world meat consumption
3 percent of world fiber production
3.4 percent of world milk production
United States
8.7 million sheep and goats
Texas, California, intermountain states
Less than 1% of livestock receipts in U.S.
Per capita consumption of lamb is less
than 1 lb. per person
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SHEEP AND GOAT PRODUCTION IN MARYLAND
23,000 sheep
Maryland Sheep & Wool Festival
Maryland Wool Pool
14,900 goats
2,400 dairy goats
< 6 certified goats/sheep dairies
12,500 meat/other goats
Counties that raise the most
sheep/goats are Frederick, Carroll,
Garrett, Baltimore
While there are some commercial and
larger farms, most are lifestyle farms.
Average producer has less than 30
animals.
PARASITES – WHAT ARE THEY?
An animal or plant that lives in or
on a host (another animal or
plant); it obtains nourishment
from the host without benefiting
or killing the host.
A (generally undesirable) living
organism that exists by stealing the
resources produced/collected by
another living organism.
Parasitism is a type of symbiotic
relationship between organisms of
different species where one
organism, the parasite, benefits at
the expense of the host.
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TWO KINDS OF PARASITES
(ecto
ecto)
External (ecto) (endo
endo)
Internal (endo)
EXTERNAL (ECTO) PARASITES
Ticks
Deer tick – lyme disease
Ked - sheep tick
Biting and sucking lice
Mites
Fleas
Flies
Nose bots
Fly strike (maggots)
Diseases with insect vectors
Bluetongue virus
Cache valley virus
stillbirths and congenital abnormalities
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SIGNS OF EXTERNAL PARASITISM
Wool or hair loss
Rough hair coat
Itching
Rubbing
Scratching
Skin discoloration
Skin rash
Tail wagging
Distress
Foul smell (wound)
Visible signs of maggots
Snotty nose
Hold nose close to the ground
Weight loss
TREATMENT OF EXTERNAL PARASITES
Insecticides
Pour-on
Sprinkle
Spray
Dust
Dip
(old-time, other countries)
Some anthelmintics
Macrocylic lactones only
Ivermectin, doramectin, moxidectin
Ivermectin is usually drug the of choice
Organic treatments
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FOUR KINDS OF INTERNAL PARASITES
Nematodes (roundworms) Trematodes (flukes)
Cestodes (tapeworms) Protozoa
NEMATODES (ROUNDWORMS)
Gastro-intestinal worms Lungworms
Bunostomum sp. Dictyocaulus filaria
Hookworm Muellerius capillaris
Cooperia sp.
Small intestinal worm Meningeal worm
Deer / brain worm
Haemonchus contortus Parelaphostrongylus tenuis
Barber pole worm
Nematodirus sp.
Threadneck worm
Ostertagia sp.
Medium or brown stomach worm
Oesophagostomum
Nodular worm
Trichostrongylus sp.
Bankrupt worm, hair worm
Trichuris ovis
Whipworm
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ROUNDWORMS ARE USUALLY THE MOST SIGNIFICANT
HEALTH PROBLEM AFFECTING SHEEP AND GOATS
Their grazing habits
Sheep graze close to the ground.
Goats are often forced to graze close to the
ground (despite their preference for grazing
high).
Sheep and goats are often kept on small
pastures with high stocking rates.
Their fecal pellets disintegrate easily.
They graze close to their feces.
The primary parasite affecting sheep and goats
is a blood-sucking killer!
Haemonchus contortus (barber pole worm)
ROUNDWORMS ARE USUALLY A MORE SERIOUS PROBLEM IN
SMALL RUMINANTS THAN OTHER LIVESTOCK
Immunity develops more slowly in
small ruminants than other livestock.
Females have relaxed immunity at the
time of parturition.
Few drugs are FDA-approved for
small ruminants, especially goats.
→ The worms have developed resistance
to drugs in all anthelmintic classes
(more so than in any other species).
? Conflicting information.
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LIFE CYCLE OF STOMACH WORMS
BARBER POLE WORM
Haemonchus contortus
Lives in the abomasum (“true” stomach).
Sucks blood from host animal.
Clinical signs: anemia (pale mucous membranes), edema (bottle jaw), loss of body condition
and weight, poor hair coat, lethargy, and death.
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BARBER POLE WORM CONTROL:
Pasture management
Clean, safe pastures
Pasture rotation/rest
Minimum grazing heights
> 3 inches
Wait until dew has lifted before grazing
Mixed-species grazing
small ruminants cows, horses
Alternative forages
e.g. Sericea lespedeza
Browsing
Proper stocking rates
BARBER POLE WORM CONTROL: other strategies
Zero grazing
Good sanitation
Nutrition
Protein supplementation
Genetic selection
Resistant breeds
Hair sheep, Gulf Coast Native
Kiko, Spanish, Myotonic
Within breed selection
The 80-20 rule
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BARBER POLE WORM CONTROL
Developed in South Africa: FAMACHA© = FAffa MAlan CHArt
Selective deworming using
FAMACHA© score plus . . .
1. Body condition score
2. Coat condition
3. Britch soiling/dags
Evidence of scouring
Consider host resistance
• Species
• Breed
• Age
• Status
BARBER POLE WORM CONTROL:
Fecal egg analysis
Qualitative (simple fecal flotation)
--of limited value.
Quantitative (eggs per gram of feces)
Modified McMaster technique (standard) →
By itself, not a good indicator of the
need to deworm.
All strongyle eggs look the same (except
nemotodirus)
Different worms produce different numbers of
eggs (barber pole worm is a prolific egg layer)
What’s a high FEC varies by worm, season, and
class of animal.
Measure of pasture contamination.
Do before and after fecal egg counts to
determine drug effectiveness (resistance).
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PROPER ANTHELMINTIC USE
TREATMENT NOT PREVENTION
1. Dose according to weight.
2. Administer drugs orally
(except Cydectin® injectable for goats).
3. Deposit drug into esophagus using oral dosing syringe with long,
metal nozzle.
4. Higher doses for goats
(except Cydectin® injectable for goats).
5. Deworm all new arrivals with drugs from two different chemical
classes.
6. Do not dose everyone in the flock or herd.
7. Do not dose on a set schedule.
8. Test for drug resistance:
FECRT - before and after fecal egg counts
DrenchRite® / Larval development assay (LDA)
WHAT ABOUT THE OTHER GI ROUNDWORMS?
Usually secondary in
importance.
Usually part of mixed worm
infections.
Cause digestive disturbances,
e.g. diarrhea.
Same life cycle.
Similar methods of control.
Same anthelmintics.
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LUNGWORMS
Found in lungs and bronchial tissues.
Some speceis require intermediate host
(snails, slugs) to complete life cycle.
Larvae are coughed up, swallowed, and
passed in feces.
Common in wet areas.
Diagnose by fecal exam (first stage larvae
in feces) and necropsy.
Difficult to diagnose.
Common anthelmintics are effective
against lungworms.
MENINGEAL WORM
Parasite of white-tail deer
Primarily harmless.
Sheep, goats, alpaca, llamas,
moose, and horses are unnatural
hosts.
Causes damage to central nervous
system death.
Snails and slugs are intermediate
host.
Larvae reach CNS 10-14 days after
ingestion of snail or slug.
Common in wet areas and where
there are a lot of deer.
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MENINGEAL WORM
Diagnose based on clinical
symptoms and necropsy.
Many differential diagnoses.
Treat with high, repetitive doses
of anthelmintics and anti-
inflammatory drugs.
Ivermectin and fenbendazole are
drugs of choice.
Treatment may or many not be
effective.
Prevent by keeping sheep and
goats away from snail and slug
habitats and deer.
CESTODES (TAPEWORMS)
Host
Moniezia sp.
Intermediate host
Echinoccus granulosus
Hydatid disease
Taenia ovis
Ovine cysticerosis
Sheep measles
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TAPEWORMS – MONIEZIA EXPANZA
Require an intermediate host (soil/pasture mite) to complete their life cycle.
Mature tapeworms shed segments (proglottids), which are filled with eggs.
TAPEWORMS – MONIEZIA EXPANZA
Tend to be non-pathogenic.
Tend not to cause any problems,
especially in adult animals.
Research shows no benefit to
treatment.
Extreme cases…
Blockage in large intestines.
Ill thrift and poor growth in
young animals.
Only certain dewormers are
effective against tapeworms.
Benzimidazoles
Safeguard®, Valbazen®
Praziquantel
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TAPEWORMS – SHEEP MEASLES
Sheep and goats serve as
intermediate host.
Do not affect health of sheep or goat,
but can cause cysts in meat and
result in carcass condemnation
Not harmful to people
Dogs (wild and domestic) are
definitive hosts.
Few symptoms in the dog.
Control by deworming dogs and
preventing dogs (wild and domestic)
from eating carrion or raw meat.
TREMATODES - FLUKES
Common liver fluke
Fasciola hepatica
Lives in bile ducts
Causes liver damage → death
Similar symptoms as barber pole worm
2-3 month life cycle.
Snail serves as intermediate host
Common in wet climates: Gulf states,
California, Pacific Northwest, and Great Lakes
region.
Diagnose by fecal analysis and necropsy.
Treat with albendazole (Valbazen®) and
clorsulon (Ivermec Plus)
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PROTOZOA – SINGLE CELL ORGANISMS
Eimeria spp.
Coccidia
Cryptosporidia sp.
Giardia sp.
COCCIDIA – EIMERIA SP.
Species-specific.
All adult sheep and goats have coccidia in
their guts.
Primarily affects weanlings.
Caused by stress, overcrowding, and poor
sanitation.
Damages lining of small intestines;
damage can be permanent.
Subclinical or clinical disease
Primary symptom is diarrhea
(smeared with blood or mucous).
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COCCIDIA – EIMERIA SP.
Diagnose with fecal analysis and
clinical symptoms.
Difficult to diagnose because…
Many causes of diarrhea
Limitation of fecal analysis
Not all coccidia are pathogenic.
Significant damage can occur before
oocytes are shed in feces.
Clinically normal animals have
oocytes in feces.
COCCIDIA – EIMERIA SP.
Prevent with good sanitation and
management.
Dewormers have no effect on
coccidia.
Prevent with coccidiostats* in
feed, mineral, or water.
Rumensin®
Bovatec®
Deccox®
Corid
Treat with Corid or sulfa drugs
(requires veterinary rx).
*Can be toxic to equines.
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PARASITE CONTROL (GI NEMATODES)
Complex problem.
There is no magic bullet or recipe.
Requires an integrated approach.
animal - parasite - pasture
Recent changes in philosophy . . .
Treatment not prevention
Control parasitism + manage drug resistance
Requires critical understanding and thinking.
Thank you for your attention.
Any questions?
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