Strongylus edentatus: development and lesions from ten weeks postinfection to patency.

Pony foals inoculated with infective Strongylus edentatus larvae were examined at necropsy from ten to 72 weeks postinfection. At ten weeks postinfection larvae were visible retroperitoneally in the liver and flanks and were recovered from the ligaments of the liver. The fourth molt was detected at 16 weeks postinfection and larvae were also recovered from the wall of the cecum at this time. By 40 weeks adult S. edentatus containing eggs were found in the contents of the cecum and colon. While many larvae migrate to remote parts of the body, it is likely that only those that attain the base of the cecum are successful in establishing in the cecum and colon as adult forms. By 36 weeks postinfection no larvae were found in the liver and up to this time none were found in the peritoneal cavity. Larvae were not recovered from the parenchyma of the lungs. Adhesions and disruption of omental architecture were frequent changes observed throughout infection. Casts of necrotic eosinophils enclosing tracks and larvae were observed beneath the intima of major veins of the cecum and colon. The liver was rough and the capsule thickened at 16 and 20 weeks postinfection and the flanks remained edematous until 36 weeks postinfection.