Two of the most frustrating but common parasites your puppy might be hosting are Giardia and Coccidia. These are not worms, but two species of protozoa — single-celled organisms that reproduce in the intestines of infected animals and shed their spores into the environment through the infected animals’ feces. These spores can survive in watery environments and soil, long enough to be incidentally consumed by other animals, either by drinking contaminated water, eating contaminated grass, or just walking through (or sitting or lying on) contaminated soil and then grooming themselves.