QUESTIONS FROM STRONGYLIDS

Question 1

Name the three migratory strongylids of horses and arrange them in descending order of size.

Answer 1

(a) Strongylus equinus
(b) S. edentatus
(c) S. vulgaris

Question 2

Pair these with the following:

(i) rounded teeth in buccal capsule.
(ii) no teeth in buccal capsule.
(iii) pointed teeth in buccal capsule.

Answer 2

Strongylus equinus – pointed teeth in buccal capsule.

S. edentatus – no teeth in buccal capsule.

S. vulgaris – rounded teeth in buccal capsule.

Question 3

Pair the same three with the following:

(i) migration to the liver and pancreas.
(ii) migration to the root of the cranial mesenteric artery.
(iii) migration to the liver and parietal peritoneum.

Answer 3

Strongylus equinus – migration to the liver & pancreas

S. edentatus – migrates to the liver and parietal peritoneum

S. vulgaris – migration to the root of the cranial mesenteric artery

Question 4

Which of the following are characteristics of the buccal capsule of ALL strongylids?

(a) presence of teeth
(b) presence of leaf crowns.
(c) presence of lips.
(d) globular shape.
(e) small size.

Answer 4

(b) presence of leaf crowns.

(d) globular shape.

Question 5

What terms are used to describe the conditions that arise from:

(a) larvae migrating in the liver.
(b) larvae migrating in the pancreas.
(c) larvae developing in subperitoneal nodules.
(d) larvae attaching to and developing in the cranial mesenteric artery.

Answer 5

(a) hepatitis
(b) pancreatitis
(c) peritonitis
(d) endarteritis.

Question 6

What is the meaning of the name Triodontophorus?

Answer 6

Having three teeth

Question 7

The strongylid nematodes have large buccal capsules and feed by drawing a plug of mucosa into the buccal capsule and digesting it off. What would you expect the consequences of this mode of feeding to be?

Answer 7

Results to be expected are inflammatory response to the damage and loss of blood and tissue fluids ingested by the nematodes and also lost by leakage from the damaged mucosa when the worms move to another site. Anaemia and hypoproteinaemia may develop as a result.

Question 8

The larvae of Strongylus vulgaris cause endarteritis and thrombus formation into the cranial mesenteric artery. What consequences of these pathological processes might be expected?

Answer 8

The thrombosis of the artery interferes with blood flow in the vessel and may contribute to ischaemia of the intestinal regions supplied which may cause infarction of areas of intestine. If severe enough this can be fatal. More commonly it produces clinical signs of colic and the animal usually recovers. It is also possible for pieces of thrombus to detach to form emboli (thromboemboli) which can travel downstream but these cause fewer problems than the endarteritis from the migrating larvae. Emboli may also block the renal and iliac arteries - the consequences are obvious but fortunately this is very rare. Even after the endarteritis has healed the wall of the artery may be weakened with the resultant formation of an aneurism. This may rupture. This sequel to S. vulgaris infection is dramatic but also fortunately, very rare.

Question 9

parasitic life cycles of the S. equinus

Answer 9

small intestine ——> liver——abdominal cavity ——–> pancreas —–> caecum and colon.

Question 10

parasitic life cycles of the S. edentatus

Answer 10

small intestine ——> liver ——> beneath parietal peritoneum ——> caecum and colon.

Question 11

parasitic life cycles of the S. vulgaris

Answer 11

small and large intestine ——> root of cranial mesenteric artery ——> caecum and colon.