Effects of Ringworm – From the Dog’s Point of View
Ringworm, also called dermatophytosis, is an infection caused by exposure to one of several forms of environmental fungi. Once the fungi become established on a dog’s hair, toenails or superficial layers of skin, characteristic ringworm signs begin to appear. By itself, ringworm is not particularly itchy and usually doesn’t cause any bothersome symptoms in affected animals. However, it does cause hair loss and scaly skin, which creates a rich environment for secondary bacterial skin infections. These can be irritating and often lead to weeping skin sores caused by licking, rubbing, scratching and biting at the infected areas.
Symptoms of Ringworm – What the Owner Sees
The classic signs of a ringworm infection are circular areas of hair loss, with dry scaly skin in the center and a red ring at the outer edges. These areas tend to gradually increase in size. In dogs, ringworm shows up most frequently on the face, ears, paws, tail and/or tail base. The signs of ringworm can easily be confused for a number of other skin disorders, including localized demodectic mange, hair follicle infections and bites from flies or other troublesome external parasites. Owners of dogs with ringworm may notice one or more of the following signs:
- Round raised regions of hair loss with varying degrees of crusting and scaling in the center and a raised red ring at the periphery; usually not accompanied by itchiness
- Irregular patchy areas of hair loss (atypical ringworm)
- Crusty skin
- Scaly skin
- Bumps on the skin
- Pustules on the skin
- Irritated, inflamed hair follicles
- Poor hair coat; broken hairs
- Dry, brittle, cracked and/or deformed toe nails
- Raised, round nodular lesions on the skin (kerions); caused by ringworm fungal infection together with secondary bacterial infection of the hair roots; most common on the muzzle and legs
Ringworm can occur anywhere on a dog’s body, including the face and legs. The infection typically stays in one primary area. The patches may grow, but they do not routinely spread to other locations on a dog’s body. However, if the dog has an impaired immune system or another underlying medical condition, ringworm is more likely to spread across its skin. Ringworm does not normally cause itchiness or scratching, but it can.
Dogs at Increased Risk
Puppies and young dogs have an increased chance of contracting ringworm infections because of their underdeveloped immune systems. Dogs whose immune status is compromised, such as those in pet stores, animal shelters or other high-density housing facilities and those with cancer, poor nutritional status, internal or external parasites or other systemic diseases, are also predisposed to developing ringworm. Dogs undergoing chemotherapy have weakened immune systems and may be predisposed to developing ringworm infection. Ringworm is highly contagious between dogs and can infect people as well.