Signs of Ring Worm in Dogs

Ringworm is a fungal infection that affects not only dogs, but cats and humans as well. The fungus that causes ringworm in dogs is typically one of three types, microsporum gypseum, microsporum canis or trichophyton mentagrophytes. Most ringworm infections occur in the fall or winter, even though the the fungus is most common in hot and humid climates. Contact with material containing the fungal spores spreads the disease to dogs, and dogs most at risk are those with weakened immune systems, such as those already sick with other diseases. Ringworm is difficult to diagnose, as the symptoms can all appear as symptoms of other diseases.

  1. Hairless Lesion

    • A common symptom of ringworm in dogs is the appearance of a lesion on the skin. The lesion looks like a patch of hairless skin, and while it is often circular, it can also be elongated and rectangular. The lesion may also appear to be patchy instead of completely hairless. The fungus affects the dog's hair because its spores attack the hair follicles on the skin. (reference 3)

    Skin Pustules

    • Pustules are small bubbles in the skin, filled with puss and consisting of white blood cells and dead bacteria. Pustules can sometimes form on the hairless lesions that appear as a symptom of the ringworm infection. Occasionally, pustules form on the skin around a lesion, instead of on the lesion itself. Pustules do not always appear on infected dogs, so the absence of them does not mean that an infection is not ringworm.

    Scaly and Red Skin

    • Sometimes the skin on and around lesions symptomatic of ringworm becomes scaly, red or raw. It is common for ringworm lesions to appear on the head and face of an infected dog, and if these lesions appear red and raw, vets often mistake them for auto-immune disorders.

    Itching

    • The lesions caused by ringworm can often be very itchy. This causes discomfort for the dog, and most dogs will not be able to resist scratching. This scratching can break the skin and even alter the appearance of the lesions. If the skin is broken and bleeding occurs,further infection of the animal may occur, and when the bleeding lesions scab over, it makes diagnosis of the true cause of the lesions very difficult.