Here's why:
* Flea benefits: Fleas are parasites that live on and feed off of the blood of their host, in this case, the dog. This is their primary source of food and allows them to reproduce and thrive.
* Dog suffers: The dog suffers from the presence of fleas. Fleas cause itching, irritation, and discomfort, potentially leading to skin infections, anemia, and transmission of diseases.
In summary, the flea benefits from the relationship, while the dog suffers. This is a classic example of a parasitic relationship.