During a necropsy of a goat with gastrointestinal issues, which of the following features would indicate a nematode infection?

The presence of a "Barber pole" appearance in the abomasum of a goat is highly characteristic of a nematode infection, specifically caused by Haemonchus contortus, commonly known as the barber pole worm. This term describes the appearance of the adult female nematode, which has a spiraled shape and coloration resembling a barber's pole, with white striped patterns from the ovaries. This visual cue is significant in diagnosing nematode infections, particularly in ruminants like goats where parasite burdens can lead to severe health issues.

Other features listed do not specifically indicate a nematode infection. For instance, the presence of tapeworms would suggest a cestode infection rather than a nematode one. Pale mucous membranes can indicate anemia, which can occur in various conditions, including severe parasitism or other diseases, but are not exclusively indicative of nematode infections. Heartworm larvae suggest a filarial infection, which involves a different type of parasite altogether. Thus, the "Barber pole" appearance is a distinctive morphological feature that directly links to nematode infections in goats.