Strongylus vulgaris

Strongylus vulgaris is a clinically important parasite causing verminous arteritis and was a very common cause of colic in horses. Its prevalence has been on the decrease since the use of wormers containing ivermectin.

Appearance

• Dark red
• Well developed buccal capsule in male

Life cycle

The S. vulgaris eggs are shed in the faeces. Under optimal conditions of high humidity and temperatures over 10 degrees, the eggs will transform into rhabditiform L1 larvae within a few days.

They then transform into L2, and subsequently L3 without leaving the parasite envelope. L3 are ingested by the host when feeding on pasture.

Pathogenesis

By larvae:

• Disruption to endothelium of blood vessel
• May cause arterial thromboembolism in the horse.
• May cause intestinal infarcts, see General Pathology

By adults:

• Accidental damage to blood vessels as a result of feeding on intestinal mucosa