 Worms can readily be seen and identified in the abomasum, and small petechiae (blood spots) may be visible where the worms have been feeding.The most characteristic lesions of "Ostertagia" infections are multiple small, white, raised umbilicated nodules 1–2 mm in diameter.These may be discrete, but in heavy infections they tend to coalesce and give rise to a "cobblestone" or "morocco leather" appearance.