Flea bites on dogs typically look like small, red, raised bumps or dots on the skin. They may appear as individual spots or clustered together, often in areas where the dog's fur is thinner or fleas can easily access the skin, such as the base of the tail, belly, groin, lower back, and armpits. The bites can also form a red or pink rash, sometimes with a faint red ring or halo around them. Due to scratching and biting from irritation, the skin may develop scabs, abrasions, or infections, and hair loss or thinning can occur around the affected areas. Flea bites are often accompanied by intense itching and discomfort for the dog, leading to noticeable scratching, biting, or licking at the spot.

Other signs to look for include flea dirt (small black specks that turn reddish-brown when wet), adult fleas visible on the dog, and potentially more severe allergic reactions known as flea allergy dermatitis resulting in more pronounced skin issues and itching.

In summary, flea bites on dogs are small red bumps or patches that provoke itching, often clustered and accompanied by other signs like scabs, hair loss, and flea dirt.