What is Ringworm?

Despite the name, Ringworm is actually a skin condition caused by a fungus. The fungus infects the hairs of the coat, causing them to break and fall out. Typically, the lesion appears as a circular area of hair loss with underlying scurfy skin. Ringworm lesions may be a little itchy but do not usually bother the animal. There are many different fungi that can cause Ringworm – in cats and dogs the most common cause is the fungus Microsporum canis.

How is the infection transmitted?

Infection can be spread by direct contact with infected animals, contact with infected hairs that have been shed, or even from objects in the environment that have come into contact with the fungus. Animals and people that are immunocompromised e.g. the young, the elderly or the sick, are more susceptible to infection. Symptoms usually appear within 14 days of contacting the fungus. It is possible for humans to contract ringworm from contact with an infected pet or the environment.

What do the lesions look like in animals?

In dogs most infections occur around the face and the paws. The lesions are usually circular with inflammed and raised edges. In cats, the ears, face and paws are usually affected. As for dogs, the lesions may be round but usually they appear more as vague areas of hair thinning and breakage with scaley underlying skin. If the claws of cats or dogs are affected, they may appear to be thick, yellow and dull. What do the lesions look like in humans? In humans the most common sign is a flat, circular skin rash that is very itchy. The edge tends to be reddened while the centre may be either dry and scaley, or moist and crusted. As it spreads the central area heals, resulting in a ring appearance.

How is Ringworm diagnosed?

The first step in diagnosing Ringworm is to examine the hair and skin under an ultraviolet light known as a Wood’s Lamp. Approximately 50% of Ringworm cases will fluoresce bright green under UV light. Unfortunately this means that if the lesions do not glow, it does not necessarily. mean that they are not caused by Ringworm. In these non-fluorescing cases further diagnostics may be required. These include examination of hairs under a microscope and growth of the fungus from a hair sample (fungal culture).

How is Ringworm treated?

There are several steps involved in the treatment of ringworm. Treat the animal – depending on the distribution and size of the affected areas, your pet may be treated topically or systemically. Topical treatment involves the application of medications such as Povidine Iodine directly to the skin twice daily for at least four weeks. If this treatment is used, the surrounding fur must be clipped away and the healthy surrounding skin treated as well as the affected area. Systemic treatment involves the administration of an oral anti-fungal drug for 4-6 weeks. These drugs disrupt the growth of the fungus. As systemic treatment is not safe in very young or pregnant animals, pregnant women should avoid contact with the drug. Prevent further contamination of the environment – some animals, especially long-haired breeds with generalized infection, may need to be fully shaved. This full body shave will usually need to be repeated 3 weeks later as the remainder of the affected hair emerges from the hair follicle. It can take long-haired animals up to 2 years to regrow their coat. Remove infected material from the environment – your pet’s bedding should be disposed of, and grooming equipment soaked in a concentrated bleach solution. The environment should be thoroughly vacuumed to remove hair fragments.Identify any asymptomatic (i.e. infected but not showing clinical signs) animals – if the infection of an animal in a multi-pet environment is recurring, it may be necessary to test all in-contact animals to identify the source of the infection. Humans are treated similarly to animals. While the lesions are usually self-limiting in healthy people, topical treatments may be required for isolated lesions. These can usually be obtained from your pharmacist. If the infection is more severe, oral medication may be required from your doctor.

Does a previous infection make me immune to Ringworm?

While resistance to a species of Ringworm-causing fungus may last for up to one and a half years following the initial infection, there are many different species of fungus that can cause the condition. This means that immunity to one species does not necessarily mean immunity to another species, and people who have previously had Ringworm can become infected again.