parasite control in dairy sheep
DESCRIPTION
Presentation for 18th Annual Symposium of Dairy Sheep Producers of North America. October 2012.TRANSCRIPT
SUSAN SCHOENIAN (Shāy-ne-ŭn)EXTENSION SHEEP & GOAT SPECIALISTWESTERN MARYLAND RESEARCH & EDUCATION [email protected] - www.sheepandgoat.com
PA R A S I T E C O N T R O L I N D A I RY S H E E P
Gastro-intestinal parasites
Primary health problem affecting sheep and lambs, especially east of the Rockies.
Severity varies by • Geographic region• Production system
Control is limited by effectiveness of anti-parasitic drugs (called anthelmintics).
Goals of internal parasite control
Eliminate parasites
1. Prevent clinical disease, production losses, and mortality, and …
2. Slow down drug resistance.
Critical control points in dairy sheep
LACTATING EWESPERI-PARTURIENT EGG RISE
EARLY WEANED LAMBS
Parasite control in dairy sheep
Parasite biology
Integrated parasite management (IPM)
1. Pasture management2. Animal factors/
management3. Deworming
Anthelmintics
Anthelmintic resistance
Internal parasite species affecting sheepIt is normal for healthy sheep to have various kinds of parasites in their gut.
1. Multi-cellular(Helminths)
a) Nematodes(roundworms)
b) Cestodes(tapeworms)
c) Trematodes(flukes)
2. Single-cell(protozoa)
Nematodes - roundworms
1. Strongyle
2. Lungworms
3. Meningeal worm
Strongyle-type worms
Haemonchus contortus
Teladorsagia (Ostertagia)
TrichostrongylusNematodirusOesophagostomumCooperiaTrichuris ovisBunostomum
Haemonchus – Trichostrongylus – Teladorsagiabarber pole worm – bankrupt worm – small brown stomach worm
Short, direct life cycles that are weather-dependent.
Can overwinter on pasture.
Ability to go into hypobiotic (arrested) state (in host) when environmental conditions are not conducive to their development.
Vary in their egg laying ability.
Eggs look same under microscope.
L3
L4, adult
L2
L1
Haemonchus contortusbarber pole worm
Primary parasite affecting sheep and lambs in warm, moist climates and/or with summer-dominated rainfall.
Most pathogenic species
Blood-sucker
Prolific egg layer
Image from University of Georgia
Haemonchus contortusbarber pole wormSYMPTOMS(due to blood and protein loss)
Anemia (paleness) Edema - “bottle jaw”
(accumulation of fluid)
Not usually diarrhea Weight loss Loss of body condition Poor stamina Sudden death
Other strongylesPrimarily Teladorsagia and TrichostrongylusSYMPTOMS(usually additive w/barber pole worm)
Production lossWeight lossDagginessScours (diarrhea)Only occasional
deathImage source: NADIS UK
Lungworms
Usually not significant
Usually additive in effect
Possible respiratory symptoms Coughing Irritated airways Pneumonia
Difficult to diagnose Usually no clinical signs Larvae (not eggs) in feces Post-mortem diagnosis
Meningeal wormdeer worm, brain worm
Normal parasite of white tail deer.
Sheep are an abnormal host. Ingest intermediate host
(snail or slug) Larvae migrates into central
nervous system where itcauses neurological disease (various symptoms).
Treat with repeated doses of fenbendazole and anti-inflammatory drugs.
Monthly treatments with ivermectin have been used as a preventative (camelids). Paralaphostrongylus tenius
Cestodes - Tapeworms Indirect life cycle; require
pasture mite as an intermediate host.
Tend to be non-pathogenic
Usually no benefit to treatment.
Treat with albendazole (Valbazen®), fenben-dazole (Safeguard®, or praziquantel (Quest Plus®). Moniezia expansa
Trematodes - Liver flukes Regional problem
(Gulf States, Pacific Northwest) Require an intermediate
host (snail or slug) Infect bile ducts - liver damage Diagnosis based on finding eggs
in feces and post-mortem Similar symptoms as barber
pole worm (anemia and bottle jaw) Treat with albendazole (Valbazen®)
or clorsulon (Ivomec® Plus).
Fasciola hepatica
Single-cell protozoa - Coccidia Species-specific
10 species known to infect sheep, but not all are pathogenic.
More complicated life cycle than most roundworms.
Cause damage to cells lining small intestines.
Most prevalent Indoor pens Feed lots Intensive grazing areas
Eimeria spp.
Coccidiosis - diagnosisFECAL EXAM
Of limited value – shouldn’t use as sole diagnostic tool Can have clinical
coccidiosis with low oocyte count and vice versa.
Not all species of coccidia are pathogenic.
Is normal to find coccidia oocytes in fecal samples.
CLINICAL SIGNS
Adults are largely immune, but serve as a reservoir of infection.
Lambs (1-6 mos., esp. 4-8 wks.) are very susceptible. Scours (diarrhea) Open fleece Weight loss Anorexia Dehydration Weakness
Coccidiosis - prevention
Good sanitation
Coccidiostats in feed, mineral, water, and/or milk replacer.
Lasalocid (Bovatec®) Monensin (Rumensin®) Decoquinate (Deccox®) Amprolium (Corid)
Coccidiosis - treatment Medicate water or
drench individual animals (preferable).
Anthelmintics1. Amprolium (Corid)2. Sulfa antibiotics▪ Di-Methox®▪ Sulmet®
Supportive therapies All Tx’s require veterinary Rx.
A method of controlling parasites using a combination of chemical and non-chemical means.
1. Non-chemical▪ Pasture management▪ Animal management
2. Chemical▪ Proper and judicious
use of drugs
Integrated parasite management (IPM)
Pasture and grazing management
1) Safe pastures2) Low risk
pastures3) Evasive grazing4) Strip grazing5) Rotational
grazing6) Multi-species
grazing
Pasture and grazing management
7) Compost manure before spreading
8) Alternative forages
9) Minimum grazing height
10) Delay grazing11) Night penning12) Zero grazing
Chicory
Sericea lespedeza
Animal management
1) Host immunity2) Lambing
management3) Nutrition4) Genetics
Targeted, selective deworming
1. FAMACHA© System
2. Five Point Check©
Fecal egg counting
FAMACHA© system
A system developed in South Africa to assess barber pole worm infection and determine the need for deworming.
Scores estimate packed cell volume (PVC) by measuring anemia using a color eye chart.
Each score has a treatment recommendation.
Eye lid color
PCV 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
Five Point Check©
An extension of the FAMACHA© system that includes evaluation criteria for other important internal (and external) parasites.
Includes five check points on the animal:
1. Ocular membrane (eye)2. Bottle jaw3. Body condition score 4. Dag score (scours)5. Nasal discharge (nose bots)
Fecal egg counting
Determining the number of worm eggs per gram of feces (EPG) in order to estimate the worm burden in an animal.
Egg count includes all strongyle eggs; cannot differentiate at egg stage.
Requires a measured amount of feces and flotation solution. A McMaster slide is used to count eggs.
Most veterinarians and many diagnostic labs do not perform quantitative egg counts (only simple fecal flotations).
Fecal egg count uses
Individual sample to determine need for deworming individual animal.
Individual or pooled samples to determine level of pasture contamination.
Pooled sample to determine treatment need in a large flock, where FAMACHA© and Five Point Check® are not practical.
Individual samples to determine effectiveness of anthelmintic treatment (FECRT) or management strategy.
Individual samples to determine genetic differences in parasite resistance.
Anthelmintics
A limited resource that should be used judiciously.
Anthelmintic families (3)Drugs in the same family have the same way of killing worms.BENZIMIDAZOLES
1.FenbendazoleSafeGuard®Panacur®
2.AlbendazoleValbazen®
3.OxybendazoleSynanthic®
MACROCYLIC LACTONES
1. AvermectinsIvermectin(Ivomec®)Eprinomectin(Eprinex®)Doramectin(Dectomax®)
2. MilbimycinsMoxidectin(Cydectin®)
NICOTINICS
1. Levamisole(Prohibit®)
2. Pyrantel(Strongid®)
3. Morantel(Rumatel®)
FDA-approved anthelmintics
SHEEP AND LAMBS
Ivermectin (Ivomec® drench)
Albendazole(Valbazen® liquid)First 30-d gestation
Moxidectin (Cydectin® drench)
Levamisole(Prohibit® drench)
LACTATING DAIRY EWES Withdrawal periods
have not been established for lactating dairy ewes.
Requires extra-label drug use, as prescribed by a licensed veterinarian.
Work with veterinarian to establish safe withdrawal periods for milk.
Anthelmintic formulationsORAL DRENCHES
FDA-approved for sheep.
Easier to administer.
Clear system faster.
Shorter withdrawal periods.
More effective
INJECTABLES
Not FDA-approved.
Sub-therapeutic levels select for resistant worms.
Longer withdrawal periods.
POUR-ONS
Not-FDA approved.
Not developed for sheep skin.
Less effective.
Sub-therapeutic levels select for resistant worms.
Anthelmintic resistanceInevitable: no treatment is 100% effective.
1) When an anthelmintic treatment fails to reduce fecal egg counts by 95% or more; severe when less than 60%.
2) There is varying degrees of resistance to all anthelmintic classes. Benzimidazoles - widespread Avermectins - widespread Moxidectin - emerging Levamisole - variable
3) Resistance varies by geographic location and farm and is influenced by past anthelmintic use.
Anthelmintic resistance Each anthelmintic family has
a different way to kill worms.
Worms develop resistance to the mechanism of worm control not individual drugs.
There is cross resistance among drugs in the same family.
If a different drug in the same family appears to work, its efficacy will be short-lived.
Determining anthelmintic resistance1) Treatment response
2) Fecal egg count reduction test (FECRT)▪ Before (d-0) and after fecal
egg counts (d 10-14)
3) DrenchRite® testLarval development assay (LDA)
Slow drug resistance by increasing refugia
Decrease frequency of treatments.
Do not treat everyone; leave some animals untreated.
Do not move treated animals to a clean pasture.
Do not deworm when there is a low level of pasture contamination.
Re-introduce suceptable worms.
Do not make it easier for worms to develop resistance to drugs By exposing worms
to sub-therapeutic levels of drugs.1) Underdosing2) Using injectable
dewormers3) Using pour-on
dewormers4) Depositing drug into
mouth instead of esophagus.
5) Persistent activity dewormers (?)
Do not introduce resistant worms to your farm To prevent the
introduction of resistant worms to your farm, deworm all newly acquired animals with anthelmintics from all three chemical classes.
For saleRam - $1,000Resistant worms - free
OTHER
NATURAL “ANTHELMINTICS”
Copper oxide wire particles
Copper sulfate Nicotine sulfate Diatomaceous earth Pumpkin seed Garlic Papaya Sericea lespedeza
(leaf meal)? Pine bark? Others
NEW ANTHELMINTICS
Monepantel (Zolvix®) Derquantel +
abamectin (Startect®)
Nematode trapping fungus
FUTURE (?) Vaccine for
Haemonchus contortus (in development)
Internal parasite resources American Consortium for Small Ruminant Parasite
Controlwormx.orgacsrpc.orgwormcontrol.orgcontrolworms.org
Maryland Small Ruminant Pagewww.sheepandgoat.com
Sheep 201: A Beginner’s Guide to Raising Sheepwww.sheep101.info/201/parasite.html
Today’s PowerPoint presentationwww.slideshare.com/schoenian
Thank ewe for your attention.
Lambs are 69% Katahdin x 31% Lacaune.