Special Veterinary Pathology

STRONGYLOSIS

Definition

• The adult worms are found in the caecum and large colon of equines.
• The life cycle is direct with involving any intermediate host
• The large strongyles includes Strongylus vulgaris, S.edentatus and S.equinus are blood suckers.
• While small strongyles are less injurious but are more in number.

Pathogenesis and lesions

• S. vulgaris
• It is double toothed, seen attached to the caecal mucosa
• The developing larva migrate into the arterioles (superior mesenteric artery and aorta)
• Along the tract of movement deposits of thrombus is seen and may occlude the lumen of artery
• Thrombosis and aneurysm of aorta and iliac arteries may cause weakness of hind limbs and severe abdominal pain.
• Verminous enteritis and verminous aneurysm are the most common lesions encountered
• S.equinus
• It is triple toothed found in caecum and rarely in the colon of equines.
• The ingested larvae penetrate intestine reach blood stream migrate through liver, heart, lung coughed up swallowed to reach large intestine
• The larvae burrowing through the wall of caecum and colon forms nodules (worm nests)
• S. edentatus
• It is toothless.
• Adult worms are seen attched to the mucosa of caecum and colon of equines
• The ingested larvae penetrate the wall of ventral colon and gets encysted in the abdominal wall for a long time
• Later they reach the serosa of small intestine where they produce subserous small raised nodules consisting of a central caseous necrotic area surrounded by erythrocytes, leucocytes, macrophages and oedema. Later, the larva penetrate the wall of intestine and enter the lumen of large intestine

Diagnosis

• Examine faeces and identify the eggs
• Worm burden may be assessed before treating the animal since light infections do not harm the animals and every animal harbours a few parasites