Difference between revisions of "Large Strongyles"

Latest revision as of 17:37, 20 August 2010

Large strongyles

Morphology

Gross

Stout worms, 1.5-5cm long
Large buccal capsule
Bursa visible to the naked eye (male worms only)

Microscopic (buccal capsule)

Double row of leaf crowns
Teeth (0, 2, 3 or more)
Dorsal gutter (channel for secretions)

Life-cycle

Infection with all three Strongylus species and Triodontophorus is by ingestion of infective stage larvae (L3) at grazing. Larvae pass down the intestinal tract and penetrate the intestinal mucosa at which point there are important species differences in life-cycle.

Pathogenicity

Adult Worms:

Plug feeders
Strongylus species:
- Large buccal capsule
- Penetrate right down to the muscularis layer and blood vessels
- Leaves small circular bleeding ulcers → anaemia if present in large numbers
Triodontophorus:
- Smaller buccal capsule
- More superficial damage
- May feed in "herds", leaving large ulcers, several centimetres across
Ulcers heal and leave scars

Pathogenesis of infection with Strongylus species larvae:

S. vulgaris:
- Potentially highly pathogenic
- Damage to cranial mesenteric artery → endarteritis → thrombosis and possibly embolism → colic
Other Strongylus species :
- Relatively non-pathogenic
- Migration of S. edentatus and S. equinus confined to roomy tissues (e.g. mesentery, liver)

Test yourself with the Horse Nematode Flashcards

Horse Nematode Flashcards

@@ Line 30: / Line 30: @@
 *''S. vulgaris'':
 **Potentially highly pathogenic
-**Damage to cranial mesenteric artery → endarteritis → thrombosis and possibly embolism → colic
+**Damage to cranial mesenteric artery → [[Verminous Endarteritis|endarteritis]] → thrombosis and possibly embolism → colic
 *Other ''Strongylus'' species :
 **Relatively non-pathogenic
 **Migration of ''S. edentatus'' and ''S. equinus'' confined to roomy tissues (e.g. mesentery, liver)
-==== Verminous endarteritis ====
+==Test yourself with the Horse Nematode Flashcards==
-*Caused by larvae of ''S. vulgaris'' within the cranial mesenteric artery
-*Also called "verminous aneurism" (misnomer as aneurism = dilatation/thinning of blood vessel wall; also, aneurisms are rare)
+[[Horse_Nematode_Flashcards|Horse Nematode Flashcards]]
-*Wall of artery grossly thickened (organising thrombi, inflammatory responses)
-*Can be detected on rectal palpation
+[[Category:Horse Nematodes]]
-*Many cases asymptomatic
-*May get embolism → infarction of areas of intestinal wall → colic or chronic ulceration (note: generally good collateral circulation; therefore colic is not inevitable)
-*Aberrant larvae may cause thrombosis in other arteries; e.g. iliac, cerebral, coronary
-*Avermectin/milbemycins or fenbendazole are used to control migrating ''S. vulgaris'' larvae[[Category:Horse Nematodes]]