♫ Bad Bugs, Bad Bugs, Whatcha
Gonna Do? ♪ : Parasites in Sheep
Dr Chris Clark
WCVM
University of Saskatchewan
Sheep Parasites
 The price of doing
business!
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PGE
Coccidiosis
Tapeworms
Fluke
Skin parasites
40
35
30
25
20
15
10
5
0
Caprine
Ovine
There’s a problem
 When we think of
parasites we think of
drugs
 Minimal drugs licensed
for parasites for sheep in
Canada
What does this mean for a sheep
producer?
 Drugs used in food
animals are federally
regulated
 Only a veterinarian can
prescribe extra-label drug
use
Its more complicated
 Drugs
 Pesticides
 Identified by DIN number
on packaging
 Identified by PCP number
on package
 Extra-label use permitted
with veterinary
prescription and
withdrawal period
 No extra-label drug use
permited
Antibiotic labels tell you all you need to
know
SC = under the skin
IM = in the muscle
IV = in the vein
Implications
 Treatment options for sheep are limited
 You need a veterinarian to prescribe parasite
treatments
 Use gFARAD for withdrawal information
The Canadian Prairies
 Good for sheep
 Bad for most parasites
 “its’s a dry cold”
 It is not bad luck it is bad
management
Coccidiosis
 Mainly a problem of
intensively raised lambs
 Especially indoors
 Outdoors needs specific
conditions
 Onset early as 8d
 Typically 4-6 weeks
 Severe diarrhea +/- blood
 Tenesmus
 Morbidity high, mortality
low
Coccidiosis
 Etiology
 E. cradallis, E. ovinoidalis
 Diagnosis
 Epidemiology, fecal, PM
 Not all that easy!
Management
 Avoid the epidemiology
 Use of coccidiostats
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Deccox
Baycox
Monensin
Amprolium
 problems
 Treatment
 TMS
Parasitic gastro-enteritis (PGE)
 Means different things in different regions
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Teladosagia (ostertagia)
Haemonchus
Nematodirus
Trichostrongylus
Trichostrongyloidea
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Eggs passed in feces
Hatch and develop to L3 on pasture
L3 ingested
Develop to L5 – adult in host causing disease
Pass eggs in feces
 Hypobiosis
 Small ruminants – Periparturient egg rise is significant
 Adults develop some immunity
Canadian Prairies
 Egg –L3 development
 Requires heat and
humidity
Haemonchosis
 Barbers pole worm
 Found in abomasum
 Blood sucker
 Prolific
 Results
 Ill thrift
 Anemia, bottle jaw
 Sudden death
Epidemiology
 Eggs passed in feces must develop to L3 on pasture
 5 day minimum
 Requirements
 Heat 18-26C (< 5 dormant, <10 nothing)
 Humidity 100%
 Canadian prairies –lucky to get one cycle
Significance
 Most years disease is rare
 If the weather is right you
have a problem
Haemonchus diagnosis
 Reality
 PM
 Clinical signs
 High egg count
Haemonchus control
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Traditionally
Deworm
Deworm
Deworm
Repeat as required
Teladosagia
 Nematode of the abomasum
 Larval forms disrupt acid production
 Type 1 disease
 Diarrhea and weight loss
 Type 2 disease
 Early spring – bottle jaw
Natural cycle in ideal conditions
Traditional control
 Deworm ewes at lambing
 Deworm lambs repeatedly throughout late summer
and fall
Nematodirus
 Intestinal worm
 Egg development in 2-3
months
 N. battus – different
epidemiology
 Diagnosis difficult as disease
is prepatent
 Egg looks like liver fluke
Trichostrongylus
 Intestinal worm with epidemiology and effects similar
to Teladosagia
 Eggs are indistinguishable
Controlling PGE
 Understanding the epidemiology
 All research is done in a different climate
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Periparturient egg rise
Egg – L3 development on pasture
Cycling in lambs
Some winter die off
Using epidemiology to control PGE
 Periparturient egg rise
 Can last 8 weeks
 Deworming ewes in association with parturition
 Can be used to minimize pasture contamination in late
spring
Using epidemiology to control PGE
 Deworm lambs at
weaning and move to
new pasture/feedlot
Anthelmintics
 BZ- Benzimidazoles
 LM – Levamisol, Pyrantel, Morantel
 AV- Avermectins
Anthelmintic resistance
 Do you have a problem?
 Fecal egg count reduction test
1.
2.
3.
4.
FEC
Weigh and dose
Wait 10d then redo FEC
Should be >85% reduction in egg count
Anthelmintic resistance
 Biosecurity
 Dose all new arrivals on arrival
 Weigh and dose
 Dose on an empty stomach
 Wait 2-3 days before turn out
Anthelmintic resistance
 Weigh and dose
 Avoid rotation of dewormer classes
 Dose when needed (egg counts, FAMACHA, BCS)
 Refugia
 Dose and move
Tapeworms
 Intestinal
 Cystic Disease
Intestinal tapeworms
 Monezia
 Not important
Intermediate hosts
Taenia ovis
Dog - sheep
The costs of disease
 2009 – 270 lambs in the 1st 6 months
”In heavy infestations the carcass is condemned.
It is commonly considered that an animal is
heavily infested if lesions are discovered in two of
the usual inspection sites including the masseter
muscle, tongue, oesophagus, heart, diaphragm
or exposed musculature and in two sites during
incision into the shoulder and the rounds.
Carcasses with C. ovis infestations may not be
acceptable for export.”
Traditional control
 Typified by Australia and New Zealand
 Routine deworming
 Mandated with appropriate products
 Feed control
 Freezing
 Cooking
Liver fluke
 Complex life cycle
 Absolute requirement for
snail
 Lymnaea truncatula
Liver fluke - disease
 Acute
 Sudden death at pasture
 Sub acute
 Poor doing fall/winter
 Chronic
 Anemia, hypoproteinemia
poor BCS
Fascioloides Magna
Sheep is an aberrant host
 Continual fluke migration
 Presentation
 Death
 Control
 Avoidance f snail areas
 Triclabendazole
Liver Fluke Control
 Albendazole
 Adult fluke only
 Triclabendazole
 V effective
 Not in Canada
Skin parasites
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Lice
Keds/ticks
Mites
Flies
Lice
 Bovicola ovis – chewing
 Linognathus spp. -sucking
Keds
 Melophagus ovinus
Ticks
Ticks latch on and feed
Have 8 legs
Do not live on the goat
Mites
 Sheep scab
 Psoroptes ovis
 Treat with an avermectin
twice (7d apart)
Fly strike in sheep
 Management problem
 Severe welfare issue