Exam II - Large & Small Strongyles

Question 1

What is the common name for the subfamily Strongylinae?

Answer 1

large strongyles

Question 2

Describe the appearance of the Strongylus vulgaris adult

Answer 2

Adults 1-2 cm in length. Mouth capsule globular. Two dorsal ear-shaped teeth in mouth

Question 3

Describe the life cycle for Strongylus vulgaris

Answer 3

Direct. Infective L₃ are ingested during grazing & penetrate mucosa. They then begin to migrate beneath the arterial intima.

They molt to L₄ during migration to cranial mesenteric & ileoclic arteries.

After 3-4 months, they molt & develop further, & migrate in arteries back to large intestine.

Develop to adults which mature sexually and copulate, after which fertile females lay eggs which are passed in feces.

PPP is 6 months

Question 4

What is the infective stage for Strongylus vulgaris?

Answer 4

L₃

Question 5

What is/are the site(s) of infection for Strongylus vulgaris?

Answer 5

Adults in large intestine.

Migrating larvae in arterial vessels of the intestine

Question 6

Describe the appearance of Strongylus vulgaris egg

Answer 6

Typical strongyle egg

Question 7

Describe any pathogenesis associated with Strongylus vulgaris

Answer 7

Larvae cause arteritis, marked thickening, thrombus formation, infarction, & death

Adults are bloodsuckers and remove plugs of mucosa

Question 8

What are some clinical signs associated with Strongylus vulgaris?

Answer 8

Larvae cause thrombo-embolus; colic

Adults cause anemia in heavy infections

Question 9

How would you diagnose large stongyles?

Answer 9

Eggs infecal exam and ID of L₂

You can’t differentiate the eggs of large and small stongyles

Question 10

What is/are the host(s) for Cyanthostomins (small strongyles)?

Answer 10

all equids

Question 11

Describe the appearance of Cyanthostomin adults

Answer 11

Adults generally less than 15 mm in length. mouth capsule not globular but rectangular or square.

Question 12

What is the PPP for Cyanthostomins?

Answer 12

6 weeks to 2-4 months

Question 13

Describe the Cyanthostomin life cycle

Answer 13

Direct. L₃ ingested during grazing. L₃ exsheath and penetrate the large intestinal wall. After 1-2 months they emerge in intestinal lumen as L₄, and develop to adults.

Cyanthostomin larvae can live in the intestinal wall for up to 2.5 years (they have an “arrested development” up to 2.5 years)

Question 14

What is/are the site(s) of infection for Cyanthostomins?

Answer 14

larvae in large intestinal mucosa.

Adults in intestinal lumen

Question 15

Describe any pathogenesis associated with Cyanthostomins

Answer 15

• Larval cyanthostominosis
• lymphocytis & eosinophilic infiltration
• Catarrhal colitis
• Protein losing enteropathy

Question 16

Primary clinical signs in Cyanthostomins are typically seen associated with the emergence of which life cycle stage?

Answer 16

L₄

Question 17

What are the primary clinical signs associated with Cyanthostomins?

Answer 17

chronic diarrhea, severe weight loss, and edema

Question 18

How would you diagnose Cyanthostomins?

Answer 18

Eggs in fecal exam (McMaster). However, you can’t distinguish between large and small strongyle eggs, so you would have to distinguish between the L₃ stage.

Question 19

Cyanthostomin eggs in foals under 6 weeks of age are due to:

Answer 19

Coprophagia (consumption of feces)

Question 20

Describe prevention & management options for Cyanthostomins

Answer 20

First you must accurately diagnose (culture the eggs & identify L₃)

Then manage the pasture (treat animals contaminating the pasture, clean up feces, mixed grazing, DO NOT OVERSTOCK)