Which parasites can be diagnosed through blood tests?

Heartworms, which are caused by the parasite Dirofilaria immitis, can indeed be diagnosed through blood tests. The most common method for detecting heartworm infection in dogs is the antigen test, which identifies specific proteins released by adult female heartworms into the bloodstream. This allows for a reliable diagnosis that is not dependent on the presence of clinical signs or the observations of the parasite itself.

In contrast, the other parasites listed do not have the same diagnosis methodology. Ticks and fleas are ectoparasites that are typically identified through physical examination of the animal's skin and fur rather than through blood tests. Intestinal worms, while they may circulate in the bloodstream in larval stages, are usually diagnosed by examining fecal samples for eggs, not through blood tests. Therefore, the ability to diagnose heartworms through blood tests distinguishes them from the other listed parasites.