What is Ringworm

Contrary to its name Ringworm is not a worm at all but a fungus called Dermatophytes. Dermaphtytes means 'plants that live on the skin'. In the past, because of the circular lesions made by the fungi they were thought to be caused by worms, hence the name ringworm.

The fungi live on the surface of the skin and in the skin follicles feeding on dead skin tissue and hair.

There are three different types of fungus that can cause ringworm but the  most predominant ones found on dogs and cats is Microsporum canis .

What does Ringworm look like on my dog?

The usual symptom is a round hairless lesion. The characteristic "ring" that we see on humans doesn't always appear as a ring on dogs. This lesion will grow in size and often become irregular in shape.

The fungi cause the hair shafts to break off and this results in patches of hair loss. Ringworm are commonly found on the face, ears, tail and paws. The lesions are scaly and may or may not be itchy and often the skin is reddened and inflamed.

How does my dog catch ringworm?

Transmission can happen by direct contact with another infected animal or person. It can be passed from dogs to cats and visa versa and from pets to humans and from humans to pets.

The fungal spores can live in the environment for a long time and can be found in carpets, bedding, grooming  equipment etc and can infect your dog when it comes into contact with them.

The incubation period is 10-12 days.  This means that following exposure to the fungus, about 10-12 days will pass before any lesions occur

In rare cases ringworm can be spread by contact with infected soil. The fungus can live for months in soil if the nutrients are right.

Fortunately the spores are easily killed with a solution of bleach and water. 500mls of bleach to 4 liters of water.

Can Ringworm spread to humans from dogs? You can contract ringworm by touching an animal with ringworm. Ringworm can spread while petting or grooming dogs or cats. You can also get ringworm from cows, goats, pigs and horses.

Are all dogs susceptible to ringworm?

Healthy adult dogs usually have a resistance to ringworm. Young dogs and puppies are more susceptible because their immune system hasn't fully developed. Many dogs are carriers of ringworm but show no symptoms. They can, however, infect other animals or humans.

Diagnosis of Ringworm

To diagnose Ringworm your vet will need to do one of the following tests. It is not possible by just looking at the skin to make the diagnosis.

Wood's Lamp
An ultra violet lamp also known as a black light. Your vet may use this as 50% of microsporum canis will glow under the lamp.

Microscopic diagnosis
Your vet may look at part of the hair or skin from the lesion under a microscope.

Culture
Your vet may decide to take a scraping from the lesion and send it away to the laboratory to see what the culture grows.

Treatment of Ringworm

If no treatment is carried out, ringworm will run it's course in two to four months and the symptoms will resolve themselves. However, treatment is recommended to save your dog from suffering any longer than necessary and to cut down the period of time they are contagious

Griseofulvin

Your vet may prescribe Griseofulvin for your dog. It is an anti fungal drug that is used for dogs with ringworm but it does have some side effects so be sure to consult your vet before giving any medication. Griseofulvin inhibits fungal reproduction.

Shampoos and Dips:
Lime sulfur dips are often recommended

Dips should be given twice a week and can be performed either by your vet or at home. Please be aware that Lime Sulfur will stain clothing and jewelry and will cause temporary yellowing of the dogs hair. It also smells very strongly of rotten eggs. Follow your vets instructions for mixing the dip.

Decontaminate the environment

Use bleach mixed at 1:10 on any surface that you can. It will kill 80% of the spores. Vacuum on a daily basis a dispose of vacuum bags which will contain the spores. Steam cleaning of carpets and furnishings will also kill a large number of the spores.

Don't forget your dogs bedding and kennel. Wash the kennel down with a bleach solution and wash the bedding in very hot water. If your dog is an inside dog confine him to one room of the house.