Which of these is NOT a symptom of ringworm?

Ringworm, also known as dermatophytosis, is a fungal infection that commonly affects the skin of pets, including dogs. It typically presents with specific symptoms that are characteristic of a fungal infection. Itchiness, circular hair loss, and scaly areas on the skin are all common manifestations of ringworm.

Itchiness occurs as the body responds to the fungal infection, and the irritation can lead to scratching, which may exacerbate the hair loss and skin irritation. Circular hair loss is a hallmark symptom, often seen as bald patches that have a defined round shape. Scaly areas are indicative of the skin's reaction to the infection and can often accompany the other symptoms.

Formation of pus-filled boils, however, is not associated with ringworm. This symptom is more typical of bacterial infections or other types of skin conditions that involve inflammatory processes leading to pus formation. Therefore, the presence of pus-filled boils suggests a different underlying issue rather than a fungal infection like ringworm.