Fatal Peritoneal Migration of Strongylus edentatus in a Foal.

This research details a case study of a 7-month old foal that suffered fatal internal damage due to a heavy infestation of Strongylus edentatus parasites, likely exacerbated by a selenium deficiency. The findings suggest a need for further investigations into both the rarity and severity of such infections and how best to prevent them.

Case Details

In summary, a young female foal was sent for a post-mortem examination after a sudden death following a two-day period of recumbency (not getting up) and the inability to open its mouth. The researchers found:

• The foal was in a thin physiological state and showed extensive internal hemorrhage, predominantly in the peritoneal wall, diaphragmatic surfaces, and the retroperitoneum (the space in the abdominal cavity behind the abdominal organs).
• Nematode larvae, identified as Strongylus edentatus, were visible on and had even penetrated and embedded into the serosal surfaces (membranes lining the cavity walls). Their presence coincided with the areas of hemorrhage.
• A portion of the abdominal diaphragm had torn, and a large colony of nematodes resided within the muscle fibers.
• Microscopically, the nematode larvae had a smooth cuticle (outer shell), complex musculature and multiple nucleated intestinal cells, and were often enclosed by regions of bleeding, neutrophils, dense connective tissue, and (though rarely) multi-nucleated giant cells.
• Severe muscle necrosis of the tongue was observed, indicating extensive tissue death. Liver testing revealed a deficiency in selenium, a vital nutrient lacking in the foal’s bodily system.

Interpretation and Implication of Findings

The report introduces S. edentatus infections as an uncommon occurrence in California, and even when present, they are typically not fatal. However, the researchers discussed some adverse factors that unusually led to this severe case:

• The foal’s selenium deficiency could have likely resulted in immunosuppression, hence promoting a higher vulnerability to intense S. edentatus infection and to the consequential muscle damage, including the diaphragm tear.
• Despite the medical record indicating ivermectin treatment—a common medication to treat parasitic infections—the severe infection suggests that there might have been inadequate deworming practices or resistance to antiparasitic medication.
• Such an unusual case warrants further research into the life cycle, pathogenicity, and resistance patterns of Strongylus edentatus, along with an exploration into the interactions of nutritional deficiencies and susceptibility to parasitic infections.