Necropsies of eight horses infected with Strongylus equinus and Strongylus edentatus.

This study explores the effects of Strongylus equinus and Strongylus edentatus infections in horses, documenting the locations of the parasitic larvae and the damage they cause to various organs.

Research Methodology

• Eight ponies, each around 18 months old, were involved in this study.
• The researchers infected the subjects with 20,000 to 30,000 infective larvae of Strongylus equinus, with less than 10% of these being Strongylus edentatus.
• The ponies were necropsied (that is, post-mortem examinations were carried out) seven months after the initial infection. The objective of this necropsy was to examine the extent of spread and damage of the infection.

Findings of The Research

• Lesions were found in several organs, including the omentum (the tissue that connects and supports the abdominal organs), liver, pancreas, ventral colon, and caecum (a pouch connected to the junction of the small and large intestines).
• In some cases, lesions were even found in the lungs.
• The horses had numerous intraabdominal adhesions and showed severe inflammation in the omentum (termed granulomatous omentitis) as a reaction to the parasites.
• Of particular note, the researchers found that the damage to the pancreas, which typically characterizes Strongylus equinus infections, was surprisingly mild. This was primarily indicated by a minor increase in eosinophils (a type of white blood cell) around the pancreatic ducts.
• Larvae-related granulomas (swellings in the tissue) were located in the connective tissue associated with the pancreas.
• The larvae of these parasites were collected from different parts of the pony bodies; the flanks, peritoneum, caecum and kidneys.
• However, the larval recovery rate was generally low, which indicates the parasites were not effectively localized or contained in the ponies’ bodies. Notably, a significant portion of the recovered larvae in some subjects was Strongylus edentatus, despite the lower initial infection rate.