Best Management Practices for Controlling Internal Parasites in Small Ruminants

1. Best Management Practices for Controlling Internal Parasites in Small Ruminants(FAMACHA© certification) SUSAN SCHOENIAN Sheep & Goat Specialist EmeritusUniversity of Maryland Extensionwww.wormx.info | sschoen@umd.edu

2. Best Management Practices • Understanding the biologyWorms, animals, and environment • Genetic selection • Management • Nutrition • Pasture managementSericea lespedeza • Managing dewormer resistance • Proper dewormer use • Targeted selective treatment • Dewormer safety • “Natural dewormers”Copper oxide wire particles • BioWorma® • Fecal egg analysis

3. The internal parasites that can infect small ruminants WormsHelminths • RoundwormsNematodesStrongyles • Flatworms • CestodesTapeworms • TrematodesFlukes Coccidia Giardia Cryptosporidium Protozoa Small ruminants usually harbor mixed infections.

4. Roundworms | Nematodes | Strongyles OF PRIMARY IMPORTANCE LESS IMPORTANT AND USUALLY LESS PATHOGENIC BunostomumphlebotomumHookworm Cooperia spp.Small intestinal worm LungwormsMuellerius capillarisProtostrongylusrufescens NematodirusThreadnecked worm • Haemonchus contortusBarber pole worm • TrichostrongyluscolubriformisBrown stomach worm • Teladorsagia circumcinctaBlack scour (bankrupt) worm • OesaphagostomumNodule worm • Parelaphostrongylus tenuis*Meningeal worm • Strongyloides papillosusThreadworms • Trichostrongylus axeiStomach hair worm • Trichuris ovisWhipworm

5. Barber pole worm Haemonchus contortus • Blood sucking worm that resides in the abomasum (true stomach). • Causes blood and protein loss (anemia; sometimes bottle jaw). • Acute or chronic disease. • Death common, sometimes sudden. • Thrives under warm, moist conditions (40-90°F). • Originally a “tropical” parasite from sub-Saharan Africa. • Genetic variability and adaptive

6. Brown stomach worm Black scour worm Trichostrongylus (small intestines) Teladorsagia (abomasum) • Cause weight and production loss “poor doers” • Impair digestion. • Common symptom is scours (diarrhea) • Not usually death • Usually found in mixed infections with barber pole worm. • Prefer cooler, wetter conditions.

7. What about tapeworms? OVER-RATED AS A PROBLEM • Cause concern because they are the only parasite visible outside the animal. • Tapeworms are not usually pathogenic. • Heavy infections may cause mild symptoms or affect gut motility (predispose lambs/kids to enterotoxemia); blockages considered rare. • Usually no benefit to treatment.Research done with lambs, not goats. • Treat with albendazole (Valbazen®) or praziquantel (in horse paste dewormers, Rx). (Moniezia expansa)

8. What about the meningeal worm? (Parelaphostrongylus tenuis) • Can cause significant problems in some animals, on some farms, and in some years. • Natural parasite of white tail deer. • Sheep/goats and camelids are abnormal hosts. • Snail/slugs are intermediate hosts. • Ingested larvae cross blood-brain barrier and cause neurological damage (symptoms). • Treat with high doses of fenbendazole (SafeGuard®, Rx) and anti-inflammatory drugs (Rx).

9. Lungworms Large and small • Large lungworms uncommon • Small lungworms more common but less (and not very) pathogenic. • Disease is rare. • Generic respiratory symptoms. • Identify 1st stage larvae in feces with Baermann technique. • Treat with same dewormers. • Prevalent in cooler, moist climates (northern locations); require intermediate host (snail or slug). • Brought-in animals could potentially introduce.

10. Liver flukes (Fasciola hepatica) • Flat, leaf shaped worms • Mostly a problem in low-lying perennial wet areas where the intermediate snail host is present. • In the US, occurs most commonly in the Pacific Northwest and Great Lake states. • Climate change with milder temperatures and heavier rainfall could increase risk of liver fluke disease. • Resulting liver damage causes similar symptoms as barber pole worm (anemia, bottle jaw, weight loss). • Albendazole (Valbazen®) is only approved dewormer effective against liver flukes (adult).

11. Coccidia (Eimeria spp.) • Single celled protozoan parasite that infects small intestines or upper colon. • Host-specific: no cross-infection between different animals, not even between sheep and goats. • Not all species of coccidia are pathogenic (2/13 in sheep; 5/17 in goats) to host. • More complex life cycle than worms: 2-3 weeks. Usually second biggest parasite problem in small ruminants.

12. Coccidiosis • Transmission is via oral-fecal route; animals consume sporulated oocyst (egg). • Affects mostly lambs/kids, 1-6 months of age. • Subclinical and clinical disease • Mature animals largely immune but serve as reservoirs of infection. • Lambs/kids develop immunity with age and continuous exposure. • Symptoms include loss of weight and body condition, poor appetite, rough hair coat, dullness, and scours (diarrhea)Should suspect coccidiosis any time young lambs/kids have gut issues. • Greater risk in confinement, but can occur on pasture, especially under intensive grazing situations (“hot spots”).

13. Preventing coccidiosis • Good sanitation and hygiene • Good nutrition and management • Management of comorbidities • Timely inclusion (and adequate consumption) of coccidiostats in feed, mineral, water, and/or milk replacer. • Lasalocid (Bovatec®) - lambs • Monensin (Rumensin®) - kids • Decoquinate (Deccox®) - lambs/kids • Amprolium (Corid) - extra label

14. Treating coccidiosis • Amprolium (Corid)Treat individually for 5 daysAvailable over-the-counter, but extra label (Vx) • Sulfa drugs (e.g., DiMethox®, Albon®)Treat individually for 5 daysPrescription (Rx) and extra label (Vx) • Ponazural (Marquis®) • Toltrazuril (generic BayCox®) • Diclazuril (Vecoxan®, Dycoxan®)

15. Control of barber pole worm and other roundworms You can’t run from worms! We can try.

16. Biology: the worms • Roundworms (nematodes)have short, direct life cycles (15 to 21 days), requiring no intermediate host. • Egg laying ability varies. Compared to other worms, the barber pole worm is a very prolific egg layer. • Microscopically, eggs look the same. Must hatch eggs to identify genus from the larvae.

17. Roundworm life cycles L4,adult L3 L1 L2

18. Hypobiosis • Under unfavorable climatic conditions, larvae undergo a period of arrested development (usually at the end of the grazing season). • Hypobiosis is how worms survive winter (or survive the dry season in tropical climates). • When favorable climatic conditions return, they resume their development and become normal, egg-laying adults. • The resumption of development often coincides with the periparturient egg rise • Worms developing from hypobiotic larvae are the primary source of pasture contamination in the spring and early summer.

19. How animals cope with parasites. sheep What happens when exposure overwhelms the sheep’s ability to develop immunity? sheep goats Evolved to use grazing behavior to stay away from worms. Ingest infective larvae (L3) when they graze close to the ground. Develop immunity with age/exposure What happens when we make goats eat within 4 inches of ground level?

20. Biology: the animals • Immunity is affected by MANY different factors: • Species • Breed • AgeExposure • Sex • Individual • NutritionBody condition • Pregnancy • Lactation • Comorbidities • Stress • Type of parasite

21. Which animals are the most susceptible to internal parasites? Lambs/kids less than 6 months of age, especially orphans. Periparturient females, especially yearlings and ewes/does with multiple offspring. Any animal that is underfed and/or in poor body condition (<2).

22. Periparturient egg rise • Temporary reduction in immunity to parasites that occurs around the time of lambing/kidding. • Results in increased fecal egg and oocyst counts in ewes/does, though not necessarily clinical disease. • May last from two weeks before up to 8 weeks after; egg counts typically peak around 30 days after lambing/kidding. • Magnitude varies by species, breed, and season. • Eggs/oocysts become primary source of infection for naïve young lambs/kids.

23. Strategies for managing the PPER in ewes/does • Deworm all ewes/does before or at the time of lambing/kidding. • Selectively deworm ewes/does before or at the time of lambing/kidding. • Lamb/kid at a time of the year when parasites are less active. • Keep animals in confinement (or dry lot; zero grazing) during periparturient period (controls worms only, won’t help with coccidia). • Increase dietary protein in late gestation ration (increase ~30% above NRC requirements). • Feed BioWorma® to periparturient females. • Select species, breeds, and animals that are more resistant to internal parasites.

24. Free-living stage • Development of eggs and larvae occurs in a temperature range of approximately 50°F to 96°F. • The minimum length of time required for development of the egg to the L3 (infective stages) is 3-4 days in Haemonchus contortus (barber pole worm).(move animals every 3-4 days to prevent reinfection) • In cooler weather, larvae survive for a longer period of time. (((longer rotations) • In hotter weather, larvae survive for a much shorter period of time. (shorter rotations) • Infective larvae don’t migrate much higher than 4 to 6 inches on grass. (don’t graze below 4 inches)

25. Genetic selection • Goats are more susceptible to internal parasites than sheep, especially hair sheep. • Some breeds of sheep/goats are more resistant to internal parasites than others. • Can select for parasite resistance in any population of sheep/goats • 20-30% of the flock/herd is responsible for shedding 70-80% of parasite eggs onto the pasture (so, get rid the heavy egg shedders). • Resistance to parasites may be related to other fitness and survival traits.

26. Sheep breeds more resistant to worms documented But not necessarily coccidia • Landrace hair sheep***Caribbean hair sheep St. Croix, Barbados Blackbelly • Wool sheep native to the Southeast***Gulf Coast NativeLouisiana and Florida NativeFlorida Cracker • Composite hair sheep St. Croix crosses) Katahdin St. Augustine (?) Royal White (?) Dorper • Conventional wool breedsTexelOther (?)

27. Goat breeds more resistant to worms less documentation But not necessarily coccidia • Meat goatsMyotonic (Tennessee Fainting Goat)***KikoSpanishBoerPygmySavanna (?) • Dairy goatsSwissNubianNigerian Dwarf (?) • Fiber goatsAngora • Other (?) Myotonic is probably the most resistant goat breed.

28. Resistance vs. resilience RESISTANCE RESILIENCE Ability of animal to tolerate parasitic infection, i.e., maintain health, thrive, grow, and reproduce. Quantified by observation or measurement of clinical parameters: bottle jaw, blood hematocrit/packed cell volume (PCV), weight gain/loss, body condition, dag score/scours, and milk production. FAMACHA© scores were initially developed as a predictor of PCV. Lower heritability than fecal egg count. FAMACHA© - low to moderate correlation with FEC • Ability of the animal to reduce the number of parasites that establish, reproduce, or survive in its body. • Quantified by fecal egg count (# of worm eggs per gram of feces, EPG), which is an estimate of the number of worms in the animal’s gut. • Generally considered to be a moderately heritable trait (20-40%). • Heritability (H2) estimates vary; more heritable at higher FEC and in sheep.

29. Ways to select for parasite resistance • Estimated breeding values (EBVs) via National Sheep Improvement Program (NSIP)/AUST LambPlan. • Enroll your flock/herd in NSIP and submit data for fecal egg count EBVs. • Select breeding stock, especially males with strong EBVs for parasite resistance (FEC). • Central performance tests • Consign rams/bucks to tests that evaluate animals for parasite traits. • Use rams/bucks from tests or breeders who participate in performance tests. • On-farm performance testing (your own records) • Select and/or cull for parasite resistance BEST

30. Estimated breeding values (EBVs) • A computer-generated prediction of the genetic merit of a sheep/goat for economically important traits such as growth, milk, prolificacy, mothering and parasite resistance. • Similar to EPDs. EBV = 2x EPD. • EBVs increase the accuracy of selection. • Genomically-enhanced EBVs increase the accuracy of selection with EBVs and allow selection at an younger age.

31. Fecal egg count EBV • FEC is usually assessed at weaning (WFEC) and post weaning (PFEC). • Fecal egg count EBV is calculated as a percentage change. - 50% = reduction in FEC of 50% + 50% = increase in FEC of 50% = Progeny would have 25% difference • By selecting for negative FEC EBVs, FEC is reduced in resulting generations, which increases parasite resistance in the flock/herd.

32. Ram and Buck Tests Artificial and/or natural challenge; FEC and FAMACHA© data RAM Buck (meat) Eastern Oklahoma State CollegeNot in 2024 Penn State UniversityPen-test: does not evaluate for parasite traits Southeastern Buck TestMississippi State University University of Florida West Virginia University*Artificial + natural challenge Others • Dorper sire (progeny) testTexas A&M AgriLifeAmerican Dorper Sheep Breeders Society • Penn State UniversityPen-test: does not evaluate for parasite traits • University of Florida • Virginia Tech Southwest AREC*Artificial + natural challenge • Others

33. On-farm selection for parasite resistance Most accurate selection for parasite resistance is via fecal egg counts. • Compare animals of similar age that aremanaged together (contemporary group) • Need fecal egg counts from all animals • Requires significant exposure to parasites(500 EPG or higher group average). • Need large enough spread between fecal egg counts: at least 1500 eggs. • Age to select animals varies. • Using other criteria for selection, such as FAMACHA© selects indirectly for resistance (FEC); slower progress. • Cannot compare with animals from other farms. Select the BEST males; cull the WORST females.

34. Management effects on parasitism • Hygiene and sanitation are very important aspects of parasite control, especially with coccidia (spread oral-fecal route). • Mixing older animals with younger animals can cause more parasite problems. Mixing goats with sheep may cause more problems (for sheep). • There are fewer worm problems when lambing/ kidding occurs during the cooler/drier times of the year, when temperatures are not as conducive to egg hatching and larvae development.

35. Management effects on parasitism • Lambs/kids raised strictly on grass (pasture) should not be weaned too early, e.g., < 120 days. • You can raise sheep/goats in confinement or dry lot (zero grazing) to virtually eliminate worm problems (but not coccidia). • Quarantine drenching: animals new to the farm should be dewormed (with drugs from all classes) in quarantine to prevent the introduction of drug-resistant worms.

36. Importance of good nutrition • Nutrition is important for immune response to worms and repairing tissue damage done by worms. • Thin, underfed animals are more susceptible to parasitism. • Supplementing animals with limiting nutrients improves their resilience and resistance to internal parasites. • Supplemental protein (especially by-pass) protein can reduce the negative impacts of internal parasitism.

37. Managing dewormer resistance • Dewormer resistance occurs when a drug loses its ability to kill worms at the standard prescribed dose. • Scientifically, it is when deworming fails to reduce fecal egg count by 95% or more. • In the US, there is resistance to all dewormers and dewormer classes. • Resistance varies by geographic area and farm and is a result of past deworming and management practices. • Resistance tends to be highest in the Southeast and for the benzimidazoles (Valbazen® and SafeGuard®) and avermectins (Ivomec®). • Some farms have resistance to all dewormers. • Many farms still have efficacy with moxidectin (Cydectin®) and especially levamisole (Prohibit®, Leva-Med®).

38. Two ways to determine dewormer resistance 1) FECAL egg count reduction test (FECRT) 2) Drenchrite® larval development assay (LDA) Lab test that determines resistance to all dewormers simultaneously from a single pooled fecal sample. Minimum FEC of 500 epg Louisiana State University is sole provider of test. Test is currently unavailable but will be available in the future once the assay has been validated in the lab. Expensive one-time cost • Compare before and after fecal egg counts from the same treated animals • Must test each drug separately. • Can use pooled or individual samples • New standards recently adopted. • Fecal egg counting can be costly but is available for a lower cost from several land grant universities. • Can learn to do your own fecal egg counts.

39. Managing dewormer resistance • Don’t deworm everyone in the group • Leave a portion of the flock/herd untreated • Don’t deworm frequently • Don’t rotate dewormers • Use combination treatments (additive) • Don’t underdose • Use oral drenches • Use proper dosing techniques • Store dewormers properly • Don’t use dewormers too long past their expiration date(s). • M A I N T A I N R E F U G I A

40. What is refugia? • Refugia is the concept of leaving some internal parasites unexposed to dewormer(s); worms “in refuge.” • Worms in refuge remain susceptible to future anthelmintic treatment. • Refugia includes life stages within the animals and on pasture. • Refugia considered essential for maintaining dewormer efficacy and slowing down dewormer resistance. https://www.beattheparasites.com/

41. Pasture and grazing management • Subdivide pastures for rotational grazing. • Consider planting tannin-rich forages, such as sericea lespedeza. • Consider planting annuals to provide clean grazing. • Maintain pastures in a vegetative state for better nutrition. • Graze taller forages • Provide browse for goats (and sheep). • Mixed grazing with other livestock. • Supplement limiting nutrient(s).

42. Pasture rest and rotation is the key to controlling internal parasites, since sheep/goats get infected with worm larvae (L3) when they graze pasture plants. • Quick rotations are ideal, not more than 3-4 days to prevent reinfection (slightly longer will probably work, since development usually takes more time). • Long rest periods are best, ~60 days in hot weather, ~90 days in cool weather. • Removing a hay crop or plowing and reseeding a pasture will cause more larvae to die. • Shouldn’t graze below 4 inches: most larvae can be found in the first few inches of plant growth (near the moisture). • Need sacrifice area(s) for when pasture is too short.

43. Sericea lespedeza Considered invasive in some states. • Perennial, warm season, non-bloating legume that grows under sub-optimal soil conditions. • Consuming SL (at least 25% of diet) by sheep/goats has resulted in reduced fecal egg counts, worm burdens, and clinical symptoms of barber pole worm. • Effect has been demonstrated in fresh forage, hay, silage, leaf meal, and pellets. • Also effective against coccidiosis. • Continuous consumption may reduce growth rates due to reduction in trace minerals. (SL; Lespedeza cuneata)

44. Dewormers for sheep and goats 1FDA approved for goats 2FDA approved for sheep

45. Dewormer safety • Dewormers generally have wide margins of safety when used according to label and ACSRPC recommendations. • Don’t give albendazole (Valbazen®) during first 45 days of pregnancy or 45 days after removal of males. • Levamisole (Prohibit®, Leva-Med®) has the narrowest margin of safety (4x). Be sure to dose accurately according to dilution. • There are anecdotal reports of levamisole causing late term abortions in goats. • Camelids: do not give albendazole to pregnant females or crias less than 6 months of age. Don’t re-dose albendazole on consecutive days. • Dispose of unused dewormers properly.

46. Extra label drug use (ELDU) • Use of any drug in any manner that is not specified on the label: species, indication, dosage, frequency, and route of administration. • Only a veterinarian has the legal authority to use or prescribe a drug extra label. • A veterinarian-client-patient relationship (VCPR) is required for extra label drug use. • Extra label drug use is usually necessary to effectively treat internal parasites in goats and camelids.

47. Veterinarian-client-patient relationship (VCPR) Required by law for a veterinarian to diagnose or treat animal(s) and prescribe or dispense medication(s). Veterinarian needs to know your animals and farm in order to make treatment recommendations. Veterinarian has responsibility for treatment. Veterinarian is available for follow-up. Requires regular visitations to your farm; varies by veterinary office but is usually every 6 to 12 months. Should be a written agreement of VCPR. Is a good thing!

48. Proper use of dewormers • Use oral dewormers • Use the right dose • Maximize treatment • Use a combination

49. Use oral dewormers • Oral dewormers put the drug where the worms are, in the stomach and intestines. • More worms are killed when dewormers are given orally. • In the US, only oral forms of dewormers are specifically formulated (and FDA approved) for sheep and goats. • Injectable dewormers are not recommended because they accelerate drug resistance and have longer withdrawal periods. They should not be given orally. • Pour-on dewormers were not developed for sheep and goat skin and fiber. They should not be given orally. • Dewormers that you feed are not recommended unless the animal is eating well and can be individually treated.

50. Use the right dose • Use labeled dosages for sheep. • Goats metabolize dewormers more rapidly than sheep, so they require higher dosages of the drugs, usually doubled (except 1.5x for levamisole). • Camelid dosages are variable. • The American Consortium for Small Ruminant Parasite Control (ACSRPC) publishes deworming charts for sheep, goats, and camelids. Wormx.info -> Topics -> Deworming -> Charts