Diagnosis of the presence of strongyles can be determined by a fecal flotation examination, but this test does not differentiate between large and small strongyles. However, a fecal culture will allow for the maturation of the larvae and the subsequent identification of the parasites infecting the horse. Horses usually do not get a strictly large or small strongyle infection; typically, they are infected with both.
Colic or abdominal distress due to Strongylus vulgaris infection may result from inflammation and obstruction of the cranial mesenteric artery. This artery can be palpated on rectal examination, and a veterinarian may be able to identify changes consistent with Strongylus vulgaris infestation
