1. Ova with bipolar plugs ........ Trichuris discolor or Trichuris ovis
2. Ova without bipolar plugs ........ Go to: 3 & 4

3. Ova embryonated, short oval to ellipsoid with smooth shell ........ Strongyloides papillosus
4. Ova NOT Embryonated ........ Go to: 5 & 6

5. Ova ellipsoid, smooth shelled with morula stage that fills all or almost all of shell ........ Strongyle-type ova (Haemonchus sp., Ostertagia sp., Trichostrongylus sp., Cooperia sp.)
6. Ova football-shaped, distinctly large, smooth shelled with morula stage that does NOT fill shell ........ Nematodirus sp.