things you should know about internal parasites

SUSAN SCHOENIANSHEEP & GOAT SPECIALISTUNIVERSITY OF MARYLAND EXTENSIONSSCHOEN@UMD.EDU

Many different internal parasites can infect small ruminants, but your focus should be on two: 1. Barber pole worm (Haemonchus contortus)2. Coccidia (Eimeria species)

BARBER POLE WORMHAEMONCHUS CONTORTUS

Nematode – roundworm

Disease can be chronic or acute

Causes anemia and bottle jaw.

Other symptoms include weight loss, loss of body condition, poor stamina, and anorexia

Does not usually cause diarrhea

COCCIDIAEIMERIA SPP.

Single-cell protozoa

Species-specific, even between sheep/goats.

Not all strains are pathogenic

Damages lining of small intestines; damage can be permanent.

Disease can be clinical or sub-clinical

Diarrhea is most common symptom, but not always.

Other symptoms include weight loss, loss of body condition, anorexia, rough hair coat, and anemia.

Worms have developed resistance to alldewormers and all dewormer classes.

Level of resistance varies by farm and geographic region.You need to know which one(s) still work on your farm.

And probably even some of the coccidiostats, e.g. Corid®, Bovatec®.

How to determine drug resistanceShould do every 2-3 years

FECAL EGG COUNT REDUCTION TEST (FECRT)

Collect fecal samples from individual animals (> 250 epg) before and after treatment with anthelmintic.

Need to collect samples for each drug or drug combination you want to test, ideally >15 animals each + an untreated group.

Compare before and after fecal egg counts to determine percent reduction. Less than 95% indicates that resistance is present.

10-14 days if testing all anthelmintics

Cost ????

DRENCHRITE TEST LARVAL DEVELOPMENT ASSAY (LDA)

Collect pooled fecal sample from 10 or more animals (> 350-500 epg).

Send sample to Dr. Ray Kaplan’s lab at University of Georgia for analysis.

Labor-intensive lab test; takes 3-4 weeks to get results.

$450 per sample

There aren’t any “natural” dewormers (yet)!But maybe natural products will reduce the number of animals that require deworming.

• With the exception of copper oxide wire particles (COWPs), there is insufficientevidence to support claims of the effectiveness of any “natural” dewormers.

• Natural products alone should not be relied on for controlling/treating internal parasites.

• If natural products are used, they should be used in combination with other integrated parasite management techniques.

• No matter what method of parasite control is used, it is imperative that animals regularly be monitored for clinical signs of parasitism and be dewormed with an effective commercial dewormer, if so required.

Moringa oleifera

Effect of copper oxide wire particles on the parasite status of bucks in the 2014 Western Maryland Pasture-Based Meat Goat Performance Test (0.5 g COWP administered on d-42)

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Study - no COWP

Fecal egg or oocyte counts are not indicative of the need to treat for worms or coccidiosis.

• It is normal for there to be some eggs in sheep and goat feces.

• Because there are so many factors involved, fecal egg counts should not be used to determine the need for deworming an individual animal.

• The decision to deworm should be based on the observation of clinical signs: anemia, bottle jaw, weight loss, scours, etc.

• Fecal egg counts should be used to…1. Determine the effectiveness of deworming

(before and after fecal treatments).2. Monitor pasture contamination.

3. Identify resistant and susceptible animals in the flock or herd.A qualitative fecal analysis is of limited

value. Don’t waste your money on a simple fecal flotation.

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IDENTIFYING RESISTANT ANIMALSMONITORING PASTURE CONTAMINATION

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Who’s most susceptible to parasites on your farm?❺PERIPARTURIENT FEMALES LAMBS AND KIDS

• Slow to develop immunity to parasites.

• Development of immunity varies by parasite.

• Development of immunity varies between breeds and between animals.

• Continued exposure to parasites is necessary to develop and maintain immunity.

• High challenges can overwhelm immunity and cause disease.

• Small ruminant females suffer a temporary loss of naturally-acquired immunity around the time of parturition.

• It may start 2-4 weeks before parturition and last for up to 6-8 weeks after.

• The eggs deposited during the periparturient egg rise are largely responsible for the infections that lambs and kids acquire during summer grazing.

Options for dealing with the periparturient egg rise

MANAGEMENT

Increase level of protein in late gestation ration.

Keep flock/herd indoors or in dry lot during periparturient period.

DEWORMING

Deworm ewes/does after first killing frost to eliminate hypobiotic worms.

◦ Use dewormer that is effective against hypobiotic larvae.

◦ Leave a few ewes/does untreated.

Deworm pregnant females during last month of pregnancy.

◦ Use dewormer that is effective against hypobiotic larvae.

◦ Leave a few ewes/does untreated.

Targeted selective treatment (TST) - only treat ewes/does that require it based on FAMACHA© scores and Five Point Check®.

All dewormers should be administered orally.Use a syringe with a long metal nozzle to deposit drug over tongue.

• Drenches are the only anthelmintics FDA-approved for sheep and goats, with the exception of Rumatel (feed product).

• The extra-label use of an injectabledewormer would be difficult to justify (in sheep).

• Injectables have longer withdrawal periods than oral formulations.

• Pour-on dewormers were not developed for goat hair and sheep wool (or hair).

• Due to sub-therapeutic levels of drugs being in the system, injectables and topical dewormers promote drug resistance.

Only a licensed veterinarian has the legal right to use or prescribe a drug “extra label.”

SHEEP

• Ivomec®, Valbazen®, Cydectin® and Prohibit® drenches are all FDA-approved for sheep at the labeled dosages.

• Unless a higher dose is deemed necessary, there is no reason for sheep producers to use anthelmintics “extra-label”.

• Withdrawal periods are not always known when anthelmintics are used extra-label.

GOATS

• Only SafeGuard® and Rumatel® are FDA-

approved for goats at the labeled dosages.

• Valbazen® is approved to treat liver flukes in goats.

• Because of the ineffectiveness of approved drugs, extra-label drug use is almost always required to effectively treat goats for worms.

• There are more violative drug residues in goats than any other species, mostly because of “off-label” use of anthelmintics.

On some farms, coccidiosis is a more serious problem than stomach worms such as H. contortus.

Prevention of coccidiosis starts with good management, nutrition, and sanitation.

Coccidiostats in mineral, feed, and water can help prevent disease outbreak and reduce sub-clinical disease. Bovatec® (lasalocid) Rumensin® (monensin) Deccox® (Decoquinate) Corid® (amprolium)

Clinical coccidiosis is treated with amprolium (Corid®) and sulfa drugs (e.g. Di-Methox®)

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Genetics offers the best long-term solution for controlling internal parasitism in small ruminants.• Parasite resistance varies by species, breed, and individual.• Genetic change is permanent

Genetic selection for parasite resistancePARASITE RESISTANCE

If animal gets infected

Measured by number of worms in gut

Estimated by fecal egg counts (FEC)

Moderately heritable

PARASITE RESILIENCE

How animal tolerates infection

Measure by packed cell volume (PCV)

Estimated by FAMACHA© score

Moderately heritable

If you’re losing a lot of animals or having to worm them a lot, you’re probably doing something wrong!• Your stocking rates are too high.• Your pastures are too contaminated.• Your animals need to be on a higher plan of nutrition.• You’re using ineffective dewormers.• You’re under-dosing your animals.• Your animals are too susceptible.

Integrated parasite management (IPM)

1) MANAGEMENT

Reducing stocking rates

Pasture rest and rotation

Clean or safe pastures

Zero grazing

Alternative forages

2) TREATMENT

Targeted selective treatment (TST) using the FAMACHA© System and Five Point Check©

Five checkpoints

1. Eye (FAMACHA score)2. Jaw (bottle jaw)3. Back (body condition score)4. Tail (dags, scours)5. Nose (nasal bots)

Coat (coat condition)

Proper use of anthelmintics

Browsing

Annual forages

Multi-species grazing

Mowing and haying

Minimum grazing height

Genetic selection

Thank you for your attention. Questions? Comments?

SUSAN SCHOENIANSHEEP & GOAT SPECIALIST

UNIVERSITY OF MARYLAND EXTENSIONSSCHOEN@UMD.EDU