1. Adult nematodes found in the Heart (right atrium) of cats ........ Dirofilaria immitis
2. Adult nematodes NOT found in the Heart of cats .......... Go to: 3 & 4

3. Adult nematodes found in the Small Intestine of cats ........ Go to: 5 & 6
4. Adult nematodes NOT found in the Small Intestine of cats ........ Go to: 11 & 12

5. Adult nematodes are thin and less than 1.0 inch (2.5 cm) long ........ Go to: 7 & 8
6. Adult nematodes are thick and more than 1.0 inch (2.5 cm) long ........ Go to: 9 & 10

7. Adult nematodes possess a large buccal cavity, armed with hooked teeth (or fangs) ........ Ancylostoma sp.
8. Adult nematodes do NOT possess a large buccal cavity ........ Strongyloides stercoralis

9. The tail of the male worm is finger-like ........ Toxocara cati
10. The tail of the male worm is triangular and NOT finger-like .......... Toxascaris leonina

11. Adult nematodes found in the Stomach of cats ........ Go to: 13 & 14
12. Adult nematodes found in the Vomitus of cats ........ Go to: 13 & 14

13. Anterior end is bunt with a cuticular collar ........ Physaloptera sp.
14. Anterior end is pointed with large lips and cervical alae ........ Go to: 15 & 16

15. The tail of the male worm is finger-like ........ Toxocara cati (may be found in stomach at necropsy)
16. The tail of the male worm is triangular and NOT finger-like .......... Toxascaris leonina (may be found in stomach at necropsy)