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EQUINE PARASITES
VT-226
Large Animal Theory II
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ASCARIDS
Description
Adults are a creamy color
Males measure = 28 cm
Females measure = 50 cm
Ova: Dark brown, thick shelled, spherical
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OXYURIS EQUI
Description White
Slender body
Pointed tail
Male measure = 12 mm or less
Females measure = 75 - 150 mm
Ova: Slender, somewhat flattened along
one side
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OXYURIS EQUIS Rat Tail
Hypersensitivity
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OXYURIS EQUI
Proctitis
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OXYURIS EQUI
One side is
characteristically
flattened,
contains an
infective L3
larva. Mucoid
plug at one end.
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OXYURIS EQUI
Cluster of eggs
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OXYURIS EQUI
L4 larva resemble carpet tacks
with a pointed tail an buccal
capsule that is used to graze on
the intestinal mucosa.
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OXYURIS EQUI
White adult females
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STRONGYLES
Small - lifecycle
L3 larvae
living free
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S. vulgaris, L3 larvae
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S. vulgaris
Large buccal capsule,
2 teeth overlapping
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S. vulgaris
Clot in the cranial
mesenteric artery
with larva in
cross-section
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S. edentatus, no teeth
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S. edentatus
Behind the peritoneum
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S. edentatus
Liver fibrosis
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S. equinus
3 teeth
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STRONGYLES
“Plug feeders”
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STRONGYLES
Description
Small strongyles Large strongyles
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STRONGYLOIDES
Description
5-25mm in length
Ova: Thin walled, larvae inside
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STRONGYLOIDES
An embryonated egg and first stage larvae
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STRONGYLOIDES
Free-living
female
Free-
living
male
Free-
living
larvae
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STRONGYLOIDES
Transmammary
transmission
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Anoplocephala & Paranoplocephala
spp.
Description
Adults: Broad, thick, white, 2.5 cm – 80 cm
in length
Average length = 15 cm
Eggs are: Amber – almost clear, shape
varies from almost round – somewhat
square
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Anoplocephala egg
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Anoplocephala egg
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Anoplocephala magna
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Anoplocephala perfoliata
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Anoplocephala scolex
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Anoplocephala ileocecal valve
infestation
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HABRONEMA
Description
10 – 15 mm in length
Eggs are: Elongated, thin walled,
larvae inside
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HABRONEMA “Summer Sores”
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Habronema granulomatous
conjunctivitis
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Habronema “summer sores”
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Habronema “summer sores”
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Gasterophilus
Bots & Bot fly
Generally nonpathogenic
Perforating gastric ulcers
Common
Gasterophilus intestinalis = Most
common species
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Gasterophilus
Female
G. intestinalis
Botfly
(bee-like)
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Gasterophilus
Eggs cemented to hair
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Gasterophilus
Close-up:
Contains an L1 that
will be viable for
several months as it
waits for stimulation
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Gasterophilus, mature L3s
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Theileria equi Description
Trophozoites are: Basophilic,
pear shaped or round, amoeboid
Maltese Cross
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Theileria equi, “Maltese cross”
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Theileria equi, “Maltese cross”
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Pediculosis (Lice)
Hematopinus asini Damalinia equi
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Pediculosis: Alopecia and Tail
Damage
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Horse biting lice and scurf