Small Ruminant

Parasite Management

Dr. Niki Whitley

The Cooperative Extension Program at

North Carolina Agricultural and Technical

State University

ncwhitle@ncat.edu; 336-285-4684

Mention of products/services in this presentation is not an endorsement

Internal parasites • Internal parasites (mostly “gut”

worms) are the primary health

problem in goats/sheep

• Goats and sheep are the most

susceptible farm livestock to

worms.

• Worms are rapidly becoming

resistant („immune‟) to dewormers.

• We need to use every method we

can to control worms not just

dewormers alone

The worst one (for sheep and goats):

Barberpole worm (Haemonchus contortus)

Although there are other worms that can cause problems, the barberpole worm

sucks blood and can kill sheep and goats very quickly. These worms cause

anemia (blood loss) that can be seen as very pale eyelids (and bottle jaw –

swelling under the jaw from loss of blood proteins). Barberpole worms do not

normally cause scours/diarrhea.

Female worm

Barberpole worms in a

goat stomach

Pale eyelids in a sheep

caused by a barberpole

worm infection

Other worms

•Trichostryonglus (Hair worm) •Nemtodirus (Thin-necked int. worm •Oesophagostomum (Nodular worm) •Trichuris (Whip worm) •Trichostrongylus axei

•Ostertagia/Teledorsagia (Brown stomach worm)

•Tape worms (only ones can “see” in feces)

Stomach and intestinal – scours, weight loss, poor doers

Others: liver fluke

Not a lot in our area

Deer worm – Meningeal worm

Coccidia are different for each species (goats vs sheep vs cattle vs chickens, etc.) Eimeria spp. Cause scouring Damage lining of small intestines; can be permanent. Treat with amprolium (Corid) or sulfa drugs. Prevent with coccidiostats Be careful with most drugs to treat or prevent this – they can be dangerous for horses (read labels!)

A parasite but not a worm - coccidia

“Whole farm” approach to parasite

management • Understand parasites

• Manage animals for their problem level

• Create clean or safe pastures

• Consider multi-species grazing

• Use pasture rest and rotation

• Consider alternative forages

• Understand the role of nutrition

• Could use zero grazing

• Use genetic selection

• Manage refugia (worms that will die when treated)

• Use multiple measures of worm infection to decide who to deworm

Barberpole worm life cycle

• Eggs hatch and grow inside manure to the

infective stage larvae (L3) which comes out of

the manure and can migrate up grass in dew

drops/water.

• Goats/sheep eat the grass with the L3 on it; In

the stomach, the L3 mature (L4 and then to

adults – both suck blood). Adult worms lay eggs

and the eggs exit the animal in feces.

•The L4 can go into a dormant (“sleeping”) state

and survive in the animal a long time; the L3

outside on the pastures have a tough sheath

(“skin”) and can live a long time (months).

•They like to develop in warm (above 60 degrees

F) and moist weather; pastures have lower worm

problems in very cold and very hot/dry periods.

Most likely to get worms

(more susceptible)

• Just weaned up to yearlings

• Orphans/bottle babies

• Late-born (in worm season)

• High-producing females

• Just before/after giving birth

• Thin animals

• Geriatric sheep

• Stressed/sick animals

• Some breeds/not adapted

• Goats

Less likely (more

resistant)

• Mature (adults)

• Dry (not milking), open or

early pregnant

• Pets (“babied”/well fed)

• Ones in good body

condition (fat)

• Some breeds or

adapted/selected animals

Management • Clean areas,

especially where

eat; use feeders

• Clean water

• Avoid overgrazing

• Do not graze below

2 inches (4+ best).

• Time birthing to

minimize parasite

infections.

Pasture or forage management • Rotate pastures to keep grazing height

up and reduce worms on pasture

• Rest 2-4 months for a pasture to be “cleaner”; 6 months best or use adult cattle or horses to clean pasture (they eat and kill goat/sheep worms but the worms do not hurt the horses or adult cattle)

• New pastures, those rotated with crops/tilled or those “burned” are “clean”

• Allow access to browse (like woods); 80% of worms are in the first 2 inches of forage

• Forages with high tannin (like sericea lespedeza) have been shown to lower worm egg counts in feces of goats and sheep

Nutritional management Animals fed well and in better body

condition are better able to handle or

resist worms; this is especially important

in late pregnancy

Higher protein has been shown to reduce

problems with worms; feeding some

grain on pasture helps them fight worms

Animals raised in confinement (barns) or dry

lots with no access to grazing have few

worm problems but could have coccidia

problems if the feeders, waterers and

barn areas are not kept clean.

Genetic selection • Breeds vary in their resistance to

gastro-intestinal parasites. – Resistant breeds: Spanish, Myotonic,

Kiko?

• There is as much difference within breeds (“lines” of animals) as between breeds.

– The 20-80 rule: around 20 percent of the herd/flock sheds 80 percent of the eggs onto pasture.

– Parasite traits are moderately heritable (inherited); you can select for it!

– Selection for parasite resistance will not adversely affect the growth of lambs or fertility of ewes.

• Resistance – Ability of host to resist infection

– Measured by fecal egg counts

• Resilience – Ability of host to withstand

challenge and/or infection.

Slow down worm immunity to

dewormers Refugia are worms that have not been exposed to deworming treatment.

• 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 (1.5-2x labeled dose for

goats; talk to vet though).

• Do not underdose.

• Deworm new animals with anthelmintics

from at least two different chemical

classes (one from all three for goats).

Without refugia, worms will eventually be

resistant to all anthelmintics.

How do we decide who to

deworm?

Eye lid

color

Packed cell

volume

Treatment

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

Can use the FAMACHA© eyelid color scoring system to estimate anemia in

sheep and goats (works for Barberpole worm only – maybe liver fluke)

Body condition score can help

decide if should deworm

Spine Transverse

processes Muscle Fat

1 Individually clearly felt, sharp, obvious

Fingers easily pass underneath

Very little No

2 Form a smooth line

with deep undulations Smooth round

edges Concave Very thin

3 Only slightly

detectable undulations

Well covered have to push firmly

to get fingers underneath

Not concave

Not convex Moderate

4 Only detectable with

firm pressure Cannot be felt at all

Maximally developed

Convex

Thick

5 Not detectable Very thick

Score: 1 2 3 4 5

Dag Scores

(“Dingle-berries”, Dirty butts)

Dag score Description Treatment

recommendation

0 No fecal soiling No indication for

treatment

1 Very slight soiling on edge of

tail No treatment

2 Slight soiling on edge of tail and

on each side Usually no treatment

3 Moderate soiling of tail and wool

Dag formation Consider treatment

4 Severe soiling extending far into

wool/hair

Severe dag formation

Treatment, crutching (trimming hair if long)

recommended

5 Very severe

watery diarrhea extending to hocks

Treatment and crutching (trimming hair if long)

essential

Other – bottle jaw, hair coat,

energy level (?)

Fecal egg counts eggs per gram of feces

• Indicate “potential” parasite burden in animal.

• Indicate potential parasite problems on the pasture.

• Use to determine if dewormers still work (fecal egg count reduction test).

• Use to determine genetic differences (who to breed or who to sell).

Fecal egg counts-what do they mean?

Cautions with FEC

• Many eggs look alike; normal regular

fluctuations in output; output varies by

season; eggs not evenly distributed in

feces; species vary in output of eggs;

inhibited larvae and L4‟s do not lay

eggs; total eggs are often a mixture of

species; diarrhea increases fecal

moisture (may dilute eggs); not all

parasites are pathogenic; possibility of

human error

Three drug classes (in US) Look for the DRUG name on the label, not the name brand

1) Benzimidazoles Chemical name ends in

'..dazole Fenbendazole, Albendazole,

Oxybendazole

2) Nicotinics Levamisole, Morantel,

Pyrantel

3) Macrocyclic lactones

Chemical name ends in “ectin”

a) Avermectins

Ivermectin, Doramectin, Eprinomectin

b) Milbemycins Moxidectin

Works best if given orally and at 1.5 to 2X the

labeled dose (see deworming chart at

www.acsrpc.org).

Use sheep products first, then cattle or horse

Consult your vet if the dewormer you want to use

is not labeled for your animal species or if you

are using more than the labeled dose

When using dewormers for

goats

Benzimidazoles (BZD)

Characteristics

• White dewormers

• Water soluble

• Broad spectrum

• Wide margin of safety

• Efficacy against tapeworms

• Efficacy against liver flukes

(albendazole)

• Widespread resistance

• Resistance is caused by

dominant gene

Products

1) Fenbendazole SafeGuard®, Panacur®

2) Albendazole Valbazen®

3) Oxfendazole Synanthic®

Nicotinic agonists

Characteristics

• 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

Products

1) Imidazothiaoles (IMID)

a) Levamisole

Prohibit®, Levasol®

2) Tetrahydropyrimidines

(TETR)

a) Morantel

Goat Care 2X

Positive Pellet

b) Rumatel®

c) Pyrantel

Strongid®

Macrocylic lactones (ML)

Products

1) Avermectins

a) Ivermectin

Ivomec®

b) Doramectin

Dectomax®

c) Eprinomectin

Eprinex ®

LongRange™

2) Milbemycins

a) Moxidecin

Cydectin®

Quest®

Characteristics

• Broad spectrum

• Wide margin of safety

• Works against external

parasites (ticks, flies, etc)

• Lasts longer than other

types

• Widespread

resistance/immunity,

especially ivermectin

Keep your dewormers working • Weigh animals to determine

proper dose (or guess HIGH).

• Do not under-dose.

• Use proper oral dosing

(drench) technique – give on

top of tongue at the back of

the mouth; make sure they

swallow it.

• Fast animals prior to

treatment.

• Give multiple anthelmintics

(with vet input) – Often they work together even if

they do not work when given alone

• Manage for refugia

How do you know if you have dewormer

resistance (immunity) on your farm?

1) DrenchRite® Larval Development Assay

• An in vitro test for the detection of resistance to all anthelmintic groups.

– Need pooled fecal sample from 10 or more animals (minimum of 6); at least > 350 epg, >500 epg preferred

• Animals with FAMACHA© scores of 3, 4, or 5 are more likely to have higher egg counts if barber pole worm is the primary parasite.

2) Fecal Egg Count Reduction Test (FECRT)

• Comparison of before and

after fecal egg counts – Benzimidizoles

7 days post-treatment

– Levamisole

7 days post-treatment

– Avermectins

14 days post-treatment

• Should include “control”

(untreated) animals in testing.

The future of parasite control

“natural” anthelmintics?

• Copper oxide wire particles

• Copper sulfate (?)

Garlic

Pumpkin seed (variable)

Diatomaceous earth

Papaya

• Pine bark

• Sericea lespedeza (leaf meal)

• Others (commercial herbals)?

• Vaccine development – They are testing a promising

vaccine in Australia

– Likely will not come to US

• New anthelmintics – Zolvix®

Monepantel (may be approved soon for sheep in US)

– Startect® derquantel + abamectin

• EPDs/DNA tests

Parasite control requires an integrated/whole farm approach.

Pasture Rest and Rotation

Strategic deworming Fecal egg counts

Mixed species grazing

Alternative forages

Good nutrition

Zero grazing

Genetic selection

Manage anthelmintic resistance

Browsing

Resistant breeds

Good management

FAMACHA©/ Selective

Deworming

Proper Anthelmintic Use Clean Pastures

Questions?