Strongyles

Strongyles are a group of parasitic roundworms belonging to the superfamily Strongyloidea. These worms are known for their significant impact on the health of various animals, particularly livestock like horses, cattle, sheep, and goats, as well as some wild herbivores. The life cycle of strongyles typically involves an indirect route, with eggs passed in the feces of an infected host. These eggs hatch into larvae on pasture.

The infective larval stages (L3) are then ingested by a new host while grazing. Once inside the host, the larvae migrate through the tissues, often burrowing into the intestinal wall or other organs, before maturing into adult worms. The adult strongyles reside in the gastrointestinal tract, where they feed on blood or tissue, causing damage and leading to a range of clinical signs.

In horses, strongyles are a major concern. Large strongyles, such as Strongylus vulgaris, are particularly notorious for their migratory habits within the arterial system, which can lead to serious complications like colic. Small strongyles, on the other hand, are more numerous and reside in the large intestine, where they can cause inflammation, diarrhea, weight loss, and poor coat condition.

Diagnosis of strongyle infections is often made through fecal egg counts, which measure the number of strongyle eggs present in a sample of feces. However, it's important to note that fecal egg counts may not always correlate with the degree of larval burden or tissue damage, especially in cases of arrested larval development. Treatment and control strategies typically involve deworming medications and pasture management practices to reduce larval contamination.