Which nematode is commonly referred to as the roundworm in dogs?

• A. Toxocara
• B. Ancylostoma caninum
• C. Trichuris vulpis
• D. Ascaris suum

Answer: (A)

The term “roundworm” in dogs refers to worms from the genus Toxocara, most notably Toxocara canis. These nematodes are large, white and live in the dog’s small intestine; their eggs are shed in feces and become infectious in the environment, which is why puppies often get infected early and can pass worms to their littermates. This genus is classically called the roundworm because of the worm’s shape and the appearance of its eggs under examination. The other options represent different parasites: Ancylostoma caninum is a hookworm, Trichuris vulpis is a whipworm, and Ascaris suum is a pig roundworm, not a typical dog parasite. Thus, the roundworm commonly associated with dogs is Toxocara.