Posted January 1, 2017 in Dog Health
Ringworm is a common yet serious disease found in dogs. Because the lesions are often circular, ringworm was once thought to be caused by a worm curling up in the tissue. However, that is not the case. In fact ringworm is caused by a fungus. The fungus causes an infection in the dead layer of the skin, hair and nails. The fungus is able to feed off of the dead tissue as a source of nutrition. Ringworm is also known as dermatophytosis and there are four types of fungi that can cause this condition.
The fungi (plural for fungus) live in hair follicles. As the organism invades and weakens, the hair shafts hairs break off at the skin line. Once the hair follicle is invaded the organism grows downward and eventually destroys the hair follicle. The area may become inflamed with ringworm. Patches of hair loss tend to be circular; as the fungi multiply the lesions may become irregularly shaped and spread over the dog’s body. These patches may be associated with scaling and crusting of the skin. The lesions are sometimes itchy but that is not always the case. In fact there are times when animals are infected but show no signs at all. It must be remembered that there are no set clinical signs that are used to diagnose ringworm.
The incubation period is anywhere from 10-12 days. This means that after exposure to the fungus and infection 10-12 days will pass before any visible signs occur.
Canine ringworm can be diagnosed by three different methods. In some cases more than one approach is utilized. Diagnosis is done by one or more of the following:
Transmission occurs by direct contact between infected and non-infected individuals. It can be passed from dogs to cats and vice versa. It may also be transmitted from animals to people as well as from people to animals. Adult humans are fairly resistant to infection unless there is a break in the skin or the immune system is suppressed. Children however are highly susceptible.
Transmission may also occur from an infected environment. The fungal spores can live in bedding or carpet for several months. These spores may be killed with a dilution of chlorine bleach and water (1 cup of bleach to 1 gallon water) where it is feasible to use it.
There are several methods to treating ringworm in dogs. The specific method recommended by your veterinarian will depend on the severity of the infection, the number of pets involved, possible presence of children in the area, and how difficult disinfecting the dog’s environment will be. The most commonly used treatment options include the following:
Treatment will not produce immediate results; in fact the areas of hair loss may get larger before they begin to get smaller. Within 1-2 weeks the hair loss should stop and there should be no new areas of infestation. However, infected pets may remain contagious for about 3 weeks.