How can dogs become infected with water-borne parasites?

• A. All these
• B. Ingesting aquatic species
• C. Drinking pond water
• D. Swimming

Answer: (B)

Many water-borne parasites rely on aquatic intermediate hosts to complete their life cycles. Dogs typically become infected when they ingest those aquatic species that carry the parasite in an infective stage. This behavior—preying on or scavenging aquatic animals such as certain fish, snails, or crustaceans—directly introduces the parasite into the dog and allows it to establish infection.

While drinking pond water or swimming can expose a dog to parasites present in water, those routes depend on the parasite having free-living stages in water and are not the primary route for many infections. Ingesting the aquatic host itself provides the key route for transmission for many water-borne parasites.