Equine- Large Strongyles, Small Strongyles and Filarioidea Flashcards
What is Dictyocaulus arnfieldi Hosts?
Donkeys
In horses adults do not reach sexual maturity and patency
What is Dictyocaulus arnfieldi Identification?
Slender nematodes in bronchi 8 cm long
What is Dictyocaulus arnfieldi Site(s) of infection?
Lungs
What is Dictyocaulus arnfieldi Life cycle?
Adult stages in bronchi lay eggs containing L1
Eggs hatch in lungs and in feces; eggs and L1 found in feces
Develop to L3, migrate from feces to herbage where ingested
What is Dictyocaulus arnfieldi Pathogenesis and lesions?
Horses: damage to pulmonary tissue
What is Dictyocaulus arnfieldi Clinical signs?
No clinical signs in donkeys
Horses: chronic, productive cough
What is Dictyocaulus arnfieldi Diagnosis?
L1 recovered in fresh feces and lung washings
Adults in lungs at necropsy
What is Dictyocaulus arnfieldi Treatment and prevention?
In endemic areas do not pasture horses and donkeys together
What is Subfamily Strongylinae Common name?
large strongyles
What is Subfamily Strongylinae Examples?
Strongylus vulgaris
Strongylus edentatus
Strongylus equinus
What is Subfamily Cyathostominae Common name?
small strongyles
cyathostomins
Large Strongyles were the main problem causing parasite.
•MCLs and other anthelmintics effectively controlled them.
•Now Small Strongyles (cyathostomins) are the main problem causing parasite.
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Large Strongyles
•3 species to be discussed
•Larvae migrate in organs; colic
•Adults bloodsuckers/plugfeeders; anemia Cyathostomins
•>50 species
•Larvae damage large intestine mucosa = colic; diarrhea
•Resistance
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What is Large Strongyles Identification?
Adult mouth capsule
All eggs the same
L3 can be distinguished
What is Large Strongyles Site of infection?
Adults large intestine
L3/L4 location species dependent
What is Strongylus vulgaris Identification?
Adult 1-2 cm
What is Strongylus vulgaris Life Cycle?
PPP 6 mo
Larvae migrate in arterial vessels of intestine
Larval stages in cranial mesenteric, ileocolic arteries and other arteries to intestine
What is Strongylus vulgaris Pathogenesis and lesions?
Larvae cause arteritis, marked thickening, thrombus, infarction, death
Aberrant larvae migration
Adults are bloodsuckers; remove plugs of mucosa
What is Strongylus vulgaris Clinical signs?
Larvae: thrombo-embolus; colic
Adults: anemia in heavy infections
What is Strongylus edentatus Identification?
Adults 3-4 cm
What is Strongylus edentatus Life Cycle?
PPP 11 mo
Larval stages in liver and abdominal
tissues (flanks)
What is Strongylus edentatus Clinical Signs/Diagnosis?
Acute (larvae): fever, anorexia
Chronic (larvae): intermittent colic
Adults: anemia in heavy infections
What is Strongylus equinus Identification?
Adults 3-4 cm
What is Strongylus equinus Life Cycle?
9 mo
What is Strongylus equinus Site of Infection
Larvae in liver
What is Strongylus equinus Clinical Signs/Diagnosis?
Larvae form hemorrhagic tracts
Adults: anemia in heavy infections
What is Large Strongyles Clinical signs?
Colic most typical
Fever, anorexia, constipation, etc.
Adults, in heavy infections, anemia
What is Large Strongyles Diagnosis?
Eggs in fecal exam and identification of L3
Can not differentiate the eggs of the cyathostomins from the large strongyles
Ultrasound, arteriography, etc for migrating larvae
Necropsy
What is Cyathostomins Identification?
Adults normally < 1.5 cm
Mouth capsule rectangular or square
Egg typical strongyle
Over 51 species
What is Cyathostomins Life cycle?
PPP: 6 wk to 2-4 mo Arrested development (up 2 ½ y)
What is Cyathostomins Site(s) of infection?
Larvae throughout large intestine mucosa
Adults in intestinal lumen (large intestine)
What is Cyathostomins Pathogenesis and lesions?
Larval cyathostominosis
Lymphocytic and eosinophilic infiltration
Catarrhal colitis
Protein losing enteropathy
What is Cyathostomins Clinical signs?
Primarily clinical signs associated with emergence of L4 Primarily young animals, older possible Chronic diarrhea; colic Seasonality Severe weight loss, edema
What is Cyathostomins Diagnosis?
Eggs in fecal examination (McMaster)
Distinguish cyathstomin L3 from large strongyle L3
Eggs in feces of foals (< 6 wk) due to coprophagia
What is Cyathostomins Epidemiology: Northern temperate climate?
Larvae arrest during winter
Emerge, adults spring
Egg counts increase in spring
What is Cyathostomins Epidemiology: Southern temperate climates?
Larvae encysts during summer
Transmission occurs during winter
What is Cyathostomins Epidemiology:
History of horses with syndrome?
Inadequate trtmt during the preceding grazing season
Over-stocked, highly infective pastures
These circumstances result in accumulation of late large burdens of encysted larvae
What is Cyathostomins Epidemiology:
Mare origin of infection
Each horse has own supply of mucosal larvae to become next season’s adults
What is Cyathostomins Treatment?
Some BZs and MCLs for mucosal larval stages
BZs, MCLs and others for adults
Resistance to all drug classes
What is Cyathostomins Resistance?
Survive treatment with an antiparasitic drug that is generally effective against the same parasite species at the same dose and against the same stage of infection. Tolerate the approved dose of an antiparasitic drug to which they were previously susceptible due to genetic mutations.
What is Cyathostomins Prevention/management?
Accurate diagnosis required Culture eggs; identify L3 Manage pasture Treat animals contaminating the pasture Clean up feces Mixed grazing Do not overstock
What is Superfamily Filarioidea Characteristics?
Indirect life cycle; all depend on insect vectors
Females lay eggs or larvae (mff) which develop to L3
Mff taken up by parasitic insects feeding on blood and tissue fluids
Mff circulate in blood of definitive host (e.g. Setaria, Dirofilaria, Acanthocheilonema)
Mff accumulate in dermal connective tissues (e.g.
Onchocerca)
What is Setaria equina Identification?
.Long slender worms 12 cm
What is Setaria equina Life cycle?
Mff in blood; Mff to L3 in Mosquito; L3 infective; L3 migrates, 2 molts to adult
What is Setaria equina Site(s) of infection?
Adults in peritoneal cavity
Microfilariae in blood
Nematodes are not pathogenic
Noted during abdominal surgery or at necropsy
What is Onchocerca cervicalis Identification?
lender nematodes up to 6
What is Onchocerca cervicalis Life cycle?
Mff in tissue spaces of skin; Mff to L3 in Culicoides spp; L3 infective; L3 migrates, 2 molts to adult
What is Onchocerca cervicalis Site(s) of infection?
Adults coiled in tissue nodules in deep connective tissue (ligamentum nuchae)
What is Onchocerca cervicalis Other?
Fibrous tissue; dermatitis; purulent lesions?
