SUSAN SCHOENIAN (Shāy-nē-ŭn)Sheep & Goat SpecialistWestern Maryland Research & Education Centersschoen@umd.edu - www.sheepandgoat.com
Alt. forages Deworm Browsing “Natural” Clean anthelmintics pastures Integrated meanscombining and coordinating Refugia IPM Nutrition diverse elements Zero grazing Manage -ment into a whole. Host Genetics Internet definition immunity Grazing Mgt.
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.
PasturePlants Animal Soil Immunity Behavior Possible clinical disease Parasite Biology Life cycle Weather Temperature Moisture
A living organism (generally undesirable) that exists by stealing the resources produced or collected by another living organism. [Wiktionary] barber pole worms in abomasum
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.
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.
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
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 (?)
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.
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.
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
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.
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.
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].
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.
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
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.
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
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
Sheep have several defense mechanisms for dealing with internal parasites: 1. Immune exclusion 2. Self-cure 3. Immunity a) Innate b) Acquired
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
St. Croix lambs ACQUIRED Immunity that is not inherited. Immunity that is acquiredINNATE (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
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.
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
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
Good sanitation Use feeders Clean water Avoid overgrazing Do not graze below 2 inches. Time lambing to minimize parasite infections.
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.
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.
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
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.
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.
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
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 (?)
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.
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.
Packed cell Treatment Eye lid color volume recommendation1 Red > 28 Optimal No2 Red-Pink 23-27 Acceptable No3 Pink 18-22 Borderline ?4 Pink-White 13-17 Dangerous Yes5 White < 12 Fatal Yes
Transverse Spine Muscle Fat processes Fingers easily pass Individually clearly felt,1 sharp, obvious underneath Very little No Form a smooth line with2 deep undulations Smooth round edges Concave Very thin Well covered Not concave Only slightly detectable3 undulations have to push firmly to get fingers underneath Not convex Moderate Only detectable with firm4 pressure Cannot be Maximally Thick developed felt at all5 Not detectable Convex Very thick
TreatmentDag score Description recommendation0 No fecal soiling No indication for treatment1 Very slight soiling on edge of tail No treatment Slight soiling on edge of tail and on2 each side Usually no treatment Moderate soiling of tail and wool3 Dag formation Consider treatment Severe soiling extending far into wool Treatment, crutching4 Severe dag formation recommended Very severe Treatment and crutching5 watery diarrhea extending to hocks essential
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.
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.
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
1) Imidazothiaoles (IMID) a) Levamisole Prohibit®, Levasol®2) Tetrahydropyrimidines (TETR) a) Morantel [Rx] Rumatel® b) Pyrantel [Rx] Strongid®
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.
1) Avermectins a) Ivermectin Ivomec® b) Doramectin [Rx] Dectomax®2) Milbemycins a) Moxidecin Cydectin® Quest® [Rx]
Broad spectrum Wide margin of safety Effective against (biting) external parasites Persistent activity Widespread resistance, reported especially ivermectin Resistance is caused by dominant gene
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
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
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.
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 [?]
Thank you for your attention. Any questions? Susan Schoenian firstname.lastname@example.org