Many occasions a creature may have worms despite the fact that you see no proof of it. Roundworms (ascarids) are a few inches in length, look like spaghetti, and may infrequently be found in the stool or regurgitation of a tainted pet; normally, however, you won’t see them.

Hookworms and whipworms are little and for all intents and purposes difficult to find in the stool or regurgitation.