Ringworm in Dogs: Identifying the Fungal Infection

Ringworm in Dogs: Appearance

Despite its misleading name, ringworm is not caused by a worm. It is a common fungal infection, medically known as dermatophytosis, that affects the skin, hair, and nails of dogs (Source 1, 3). This infection is caused by dermatophytes, which are pathogenic fungi (Source 1).

Classic Appearance of Ringworm

In dogs, ringworm often presents with distinct visual signs. One of the most common indicators is the presence of circular patches of hair loss (Source 2, 5). These lesions may start small and gradually expand.

The skin at the edges of these bald patches often appears reddened and inflamed (Source 5). This inflammation can make the affected area stand out against the surrounding healthy skin.

Within and around the lesions, the skin may be scaly or crusty (Source 5). This flakiness can resemble dandruff and is a key characteristic of the fungal infection.

While more common in humans, dogs can also exhibit a raised, red ring-like border around the affected areas (Source 2, 5). This "ring" is where the infection gets its common name.

Variations in Ringworm Appearance

Ringworm in dogs can manifest in several ways beyond the classic circular pattern. It may appear as irregularly shaped bald spots rather than perfectly round ones (Source 5). These patches can vary in size and distribution across the dog's body.

Dandruff-like scales are frequently observed on the skin within and surrounding the affected areas (Source 5). This scaling is a result of the fungal activity on the skin's surface.

Some dogs may develop scabs or darkened skin in the infected regions (Source 5). These scabs can indicate secondary irritation or scratching due to itching. The skin may also appear hyperpigmented.

The hairs within the affected patches tend to be dry and brittle (Source 5). They may break easily, contributing to the appearance of hair loss. The fungus feeds on hair follicles and dead skin cells (Source 5).

Ringworm can affect not only the skin and hair follicles but also the nails (Source 1, 2). Nail infections, though less common, can lead to brittle, discolored, or misshapen claws.

Common Locations for Ringworm

Ringworm can appear on any part of a dog's body (Source 5). However, certain areas are more prone to infection. These include the face, ears, paws, and tail.

Puppies, senior dogs, and immunocompromised dogs are more susceptible to widespread ringworm infections (Source 2). In these cases, the lesions may be more numerous and cover larger areas.

Visual Example

Here is an example of what ringworm can look like on a dog: