Small Ruminant GI Parasites - The Basics and Beyond: Alphina Ho Watson, DVM Research Veterinarian International Goat Research Center Prairie View ...
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The Basics and Beyond: Small Ruminant GI Parasites Alphina Ho Watson, DVM Research Veterinarian International Goat Research Center Prairie View A&M University May 10, 2018
“Parasites”
• Ectoparasites
• Lice
• Mites
• Maggots (“screwworms”)
• Endoparasites
• Gastrointestinal Worms
• Roundworms
• Flatworms: Tapeworm, Flukes
• Protozoan
• Toxoplasmosis, Coccidian organisms (Eimeria spp.)
• Blood parasites
• Babesia, Anaplasmosis, etc.
Gastrointestinal Nematodes
• Roundworms
• “HOT” Complex
• Haemonchus
• Ostertagia
• Trichostrongylus
• Trichuris
• Cooperia
• Nematodirus
• Bunostomum
Barber-pole Worm
Roundworms of Note
• Haemonchus contortus
• “Barber-Pole Worm”
• Damages abomasal wall & sucks blood
• Trichostrongylus spp.
• Burrows into abomasal & intestinal lining
• Ostertagia ostertagii
• Undergoes hypobiosis
• Eggs look the same under microscope
(Photo: cal.vet.upenn.edu)
Hypobiosis
(L4 can go into a
dormant state and
survive in the animal;
even with no
reinfection, can see 2-3 weeks
adults in animals 3-6
(prepatent
months later)
period)
(L3 living in
pasture have a
tough sheath
and can survive
for months)
(Source: www.farmanimalhealth.co.uk and Dr. Niki Whitley, FVSU)
Symptoms
• Weight loss/skinny
• +/- Diarrhea (dirty tails)
• Anemia
(Photo: Nexus Academic Publishers)
• Pale conjunctiva, gums
• “Bottle Jaw”
• Edema from protein loss
• Weak/Anorexic
• ADR, down, lateral
(Photos: Courtesy Dr. Niki Whitley, FVSU)
Dewormer Resistance – “Super Worms” • “a genetic change in a population of worms that allows some individual worms to survive and multiply despite administering the proper dose of dewormer at the right time” • In US currently, resistance exists to ALL anthelmintics used to treat small ruminants • level varies by geographic region and farm • One size DOES NOT fit all!
How Do I Deworm?
Multi-pronged approach “Strategic Deworming” - Deworming only the animals that need to be dewormed, in combination with pasture rotation and non- chemical means to control the effects of GI parasites in the herd. • Determine parasite load • Combination deworming • Maintain refugia • Non-chemical control
Determine Parasite Load: FAMACHA • Developed in South Africa • Haemonchus contortus ONLY! • Conjunctival anemia scoring • 1= red, “Healthy” • 2= red-pink, “Very good” • 3= pink, “OK” • 4= pink-white, “Deworm” • 5= white, “In trouble” • Training workshops teach how to (Photo: Katherine Petersson, www.wormx.info) perform & score properly • Make sure animal is not anemic for another reason!
Determine Parasite Load: Body Condition Score • Manual palpation of lumbar, shoulder and hip regions • Estimate of overall animal health and nutrition -> healthier = less susceptible • 1= really skinny • 3= just right • 5= really fat • Doesn’t directly measure parasitism • if really skinny, suspect parasitism • supplements information from FAMACHA
Determine Parasite Load: FECRT
• Fecal Egg Count Reduction Test
• Collect feces on day of deworming
• before drenching
• Process feces and count eggs recovered
• under microscope
• Collect another sample in 7-10 days, count eggs
• >90% reduction means dewormer is effective
•Combination Deworming: Drugs • Benzimidazoles • SafeGuard, Panacur (fenbendazole) • Valbazen (albendazole) – watch out for pregnant! • Macrocyclic lactones • Ivomec (ivermectin – sheep drench) • Cydectin (moxidectin – sheep drench) • Imidazothiazole • Prohibit, LevaMed (levamisole)
FDA-approved antiparasitic drugs for sheep and goats
(Source: US FDA)Combination Deworming: “Rules”
• Use a combination of drugs from
DIFFERENT classes
• Preserve the efficacy of available drugs
• e.g., a benzimidazole, a macrocyclic lactone
and levamisole together
• DO NOT UNDERDOSE
• Weigh all animals, use correct dose for
weight
• If estimating, dose for heaviest animal
• Make sure you’re drenching properly
• over back of tongue, swallows
• DO NOT deworm everyone
• Select for resistant worm population (Source: https://ahdc.vet.cornell.edu/programs/NYSCHAP/docs/GoatDewormerChart.pdf)“Rules”, con’t • Hold off feed overnight • Increase worm exposure to dewormer • Dry-lot for 3 days • Before turning into new pasture • Multiple days’ dosing can improve response • e.g., drenching Panacur 3 days in a row • DO NOT use ‘long-acting’ dewormers (e.g., LongRange) • Great way to develop resistant worms!
DO NOT use cattle pour-ons in goats!
Deworming Combo at PVAMU • Cydectin (moxidectin) & Safeguard (fenbendazole) • Reduction of egg counts very unimpressive • Prohibit (levamisole) as a last-line dewormer (alone, when nothing else worked) • November 2017, started combining Cydectin, Valbazen (albendazole) and Prohibit (levamisole) • Reduction in egg counts has improved dramatically
Maintain/Establish “Refugia”
• Population of worms that are susceptible to the chemical
dewormers
• will die when animals are dewormed
• They help to keep the resistant worm numbers low:
• compete for same resources
• hardier than resistant worms
• Do not blanket-deworm entire herd!
• decimating the susceptible population actually selects for resistant
worms (only they will survive to re-seed your pastures)!Non-chemical control: Pasture Rotation • Move goats whenever grass
Non-chemical control: COWP Copper Oxide Wire Particles • Most efficacious against H. contortus • +/- control of other worms + coccidia • 0.5 to 1 gram/head in young, 2 to 4 grams/head in adults • Use lower doses in sheep (toxicity!), small breed goats • Higher doses: no more than 2 treatments in one grazing (Photo: Susan Schoenian) season, wait >6 weeks between doses • Used in conjunction with anthelmintics for best effect • NOT copper sulfate (toxic!)
Non-chemical control: Lespedeza
Lespedeza cuneata L. (sericea lespedeza)
• Tannin-containing legume
• Many varieties - most can’t handle grazing, too
stemmy
• AU Grazer™ - developed by Auburn University and
the Alabama Agricultural Experiment Station
• more palatable, withstand grazing
• studied most with H. contortus, but individual trials show
effectiveness against some Trichostrongylus and
Ostertagia
• also Eimeria (coccidia)
• prevents bloat?
• Hay, leaf meal pellets, seeds; ensiled?Non-drug control: “Resistant” animals Select for less-susceptible animals: • Maintain detailed flock/herd records • Deworming frequency (if constantly deworming, CULL) • Fecal Egg Counts (if consistently high when deworming, CULL) • FAMACHA scores and BCS (if consistently pale and skinny, CULL) • Maintain genetics of those who rarely need to be dewormed, have good BCS and FAMACHA scores, low FECs • EBVs/DNA tests • What if pale on FAMACHA, but decent BCS and “acts normal”? • R/O other disease processes • If you keep this animal, is it contaminating your pastures??
Suggested “Parasite-resistant” Breeds
• Spanish
• Myotonic (“Tennesee Stiffleg”)
• Kiko
• BUT there is as much difference within breeds (“lines” of
animals) as between breeds
(Information courtesy of Dr. Niki Whitley, FVSU)Non-chemical control: BioWorma • Duddingtonia flagrans - a nematophagous (Images: www.duddingtonia.com) fungus naturally in environment • Spores fed as feed supplement, pass through animal to feces, traps and “eats” worm larvae in pasture • Reduces pasture contamination (not worm burden in animal) • Just approved in Australia, not in US… yet
Additional Alternatives?
• Pine bark ( FEC?) • Worm replacement?
Ò Garlic • Vaccine development?
• vaccine exists in other countries
Ò Pumpkin seed (does not prevent, kills those
present)
Ò Diatomaceous earth
• Will not be available in U.S.?
Ò Commercial herbal
dewormers
• All alternative support, not
replace, chemical dewormers
(Information courtesy of Dr. Niki Whitley, FVSU)Review • Detemine parasite load • FAMACHA score 4 or 5 (+/- 3); Body Condition Score 2 or 1 (+/- 3) • Only deworm those who need to be dewormed • use dewormer combo (from different classes) • Maintain refugia • Non-chemical control • Pasture rotation • Rotational-grazing • COWP • Resistant animals • Lespedeza • Nematophagous fungus
Parasite control requires an
integrated/whole farm approach!
Mixed species
grazing Proper Anthelmintic Use
Clean Pastures
Browsing
Genetic selection
Strategic
Fecal egg counts
deworming
FAMACHA©/ Five Point
Good nutrition Check/ Selective
Good Deworming
management
Pasture Rest and
Manage anthelmintic
Rotation
resistance
Resistant breeds
(Image courtesy of
Dr. Niki Whitley,
FVSU)
Zero grazing Alternative foragesAU Grazer™ Lespedeza Resources
• Sims Brothers, Inc.
3924 County Rd. 87 Union Springs, AL 36089
(334) 738-2619 FAX: (334) 738-2620
email: simsbrothers@yahoo.com
Web page: http://simsbrothers.com/
• Tennessee Farmers Cooperative
Web page: https://www.ourcoop.com
à Product Catalogue à search ”lespedeza”Worm Resources • http://www.wormx.info/ - Great site with current information on small ruminant parasite control and lots of Facts Sheets • https://www.duddingtonia.com/ - General information about D. flagrans and how it can help reduce GI nematodes • http://www.aasrp.org/ - American Association of Small Ruminant Practitioners’ website (for veterinary resources, to look for a vet in your area who works on goats/sheep, camelids and wild ungulates, etc.)
Thank You!
Deworming Quiz (Taken from wormx.info)
True or false? Sheep and goat producers often underestimate the weight of their animals and do not give enough dewormer so many more worms survive treatment, increasing drug resistance. True Animals should be weighed individually or dosed according to the heaviest animal in the group and dosing equipment should be checked frequently for accuracy. The only exception to the rule of dosing according to the heaviest animal is when using levamisole, which can be toxic at high levels.
True or false? Goats metabolize drugs much more rapidly than other animals and require a higher dose than sheep or cattle to achieve effectiveness and slow development of resistance. True It is generally recommended that goats be given a dose 2X higher than the sheep or cattle dose on the label for all dewormers except levamisole; levamisole should be administered at 1.5X the label dose and individual animals should be weighed due to the risk of toxicity. By law, it is necessary to consult a veterinarian before using any drug in a manner not specifically listed on the label. Pour-on formulations are poorly absorbed and should not be used.
True or false? When giving a dewormer by mouth (drenching), it is important to deliver it over the back of the tongue so the full dose is swallowed and lodges in the rumen. True If the drench is not given over the back of the tongue, the esophageal groove may close and most of the dewormer will bypass the rumen. This will shorten the duration of action and effectiveness will be reduced.
True or false? Witholding feed for 24 hours before deworming increases the rate of digesta transit and decreases drug availability and effectiveness. False Witholding feed actually slows the passage of digesta, allowing more contact time between the dewormer and the parasites which increases effectiveness. This is especially true when using the benzamidazoles (Safeguard®, Valbazen®) and ivermectin. However, bear in mind feed should never be withheld from a ewe or doe in the final weeks of pregnancy due to the risk of pregnancy toxemia.
True of false? Giving two doses of the same dewormer, 12 to 24 hours apart, is dangerous and costly. False Repeat dosing is a safe and effective way to increase contact time between parasites and the dewormer. If using levamisole, repeat the dose at 24 hours (rather than 12) for safety. Repeat dosing can be used in addition to withholding feed, especially with the benzamidazoles, to enhance the contact time between parasites and the drug.
True of false? Rotating or changing dewormers to a different class with each treatment causes resistance to develop simultaneously to more than one drug. True It is recommended that one drug be used until it is no longer effective and then the drug should be switched. If a rotation is used, resistance develops slowly but surely to all of the products used but the producer is often unaware until multiple drug resistance is severe.
True or false? Using 2 or more different dewormers at the same time offers a significant advantage in delaying resistance because it reduces the number of worms that survive treatment. True In order for a parasite to survive after administration of two dewormers from two different classes, it has to have resistant genes to both drugs (which rarely occurs). In Australia and New Zealand, the use of combination dewormers is routinely practiced and has been for many years.
True or false? A good practice is to deworm all of the animals in the herd then move them immediately to a new, clean, safe pasture. False It is very important not to move treated animals immediately to clean pasture unless a portion of the herd was not treated with a chemical dewormer. Although this does not seem to make sense, if only the resistant (bad) worms survive treatment, they are also the only ones to multiply and contaminate the pastures. The last thing any producer wants is a pasture contaminated with only the larvae of resistant parasites
True of false? Dewormer resistant worms can only come from 2 sources; either home-grown from poor deworming practices or they are purchased when new animals enter the herd. True In a closed flock or herd, resistance within a worm population is typically a slow, gradual process requiring many years for the genetic changes to take place. Alternatively, resistant worms can be purchased, and bypass the many years of genetic change necessary to reach high levels. Depending on how many animals with resistant worms are purchased, treatment failures can occur practically instantly in a herd that never had previous problems.
True or false? Once dewormer resistance is diagnosed as a clinical problem, reversion to susceptibility will likely never occur. True Unfortunately, unless the effectiveness of a drug is monitored over time with a fecal egg count reduction test (FECRT), resistance will not be noticed until there is failure, resulting in sick or dead animals despite correct use of that dewormer. Once resistance to a certain class of drug is noticed, it is a permanent change in the genetic makeup of the parasite.
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