Background:
Despite its name, ringworm infection is not caused by a worm but by
a fungus. Similar to athlete’s foot in humans, the fungus causes a
superficial infection of the skin and hair follicles. Three types of
fungus are usually responsible for these infections: Microsporum
canis, Microsporum gypseum and Trichophyton mentagrophytes.
Ringworm is generally a disease of
younger animals. The fungus is transmitted by spores which live in
soil or may be transmitted between pets on brushes, toys and
bedding. Humans can also contract an infection if they come into
contact with an infected pet. Children and elderly people are
especially at risk.
Clinical
Signs:
In humans, ringworm infections typically appear as circular, red
raised lesions on the skin, hence the name. However, in cats and
dogs, the infection does not always appear as a ring on the skin. In
pets, ringworm infection may cause patchy hairlessness in a single
area or in several areas of the body. Dogs are most commonly
affection on the nose, ears, face and paws. Cats also are affected
on the head, but often have spores or hairless patches on their
limbs as well. These spots are rarely itchy, but a secondary
bacterial infection may cause the lesions to scab, bleed or itch.
Diagnosis:
Ringworm is diagnosed by veterinarian with a few simple tests. The
spores of the fungus will glow green under ultraviolet light,
although occasionally this may not be seen. A fungal culture may be
grown from a sample of the hair surrounding the lesions. Fungal
cultures take awhile to grow and develop, so your veterinarian may
prescribe medications in the interim. Hair follicles can also be
microscopically examined in the hopes of identifying spores.
Treatment:
Treatment of ringworm infections varies depending on the spread of
infection. If the infection is very local to one spot, the area may
be shaved and cleaned using special shampoos. A topical anti-fungal
medication, such as 2% miconazole, may be applied to the lesion
regularly by the owner. In more generalized cases of ringworm, your
veterinarian may recommend not only clipping the hair and using
topical therapy, but also a prescription oral medication called
Griseofulvin (Fulvicin).
Treatment of ringworm requires
great care by owners. Gloves should always be worn when handling
infected animals. Bedding should be discarded and grooming tools
should also be sterilized with a 1:10 bleach solution. Ideally, pets
should be isolated to prevent spreading spores onto carpets and
furniture. If this is impossible, carpets and furniture should be
frequently vacuumed to pick up spores and hair.
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