Ringworm is a parasitic disease well known to the general public. It is responsible for hair loss in animals. It is feared given its great contagiousness and the owners’ difficulty in getting rid of it. It requires long treatment of animals as well as treatment of the environment.
What is ringworm?
Ringworm is due to Mushroom which feed on keratin and develop in the hairs, dander, claws, eyelashes and the stratum corneum. They are found in animals and humans as well as in the environment. The mushrooms are very resistant in the outdoor environment.
In dogs and cats, several fungi can be responsible for ringworm such as:
- Microsporum canis : it is the main ringworm agent.
- Trichophyton mentagrophytes : this fungus is found in the outside environment. It mainly affects rodents, dogs and cats. In hunting dogs for example, we can find ringworm lesions at the level of the muzzle (this is above the nose, between the nose and the eyes). Indeed, they put their noses in the burrows in search of small rodents and can thus become contaminated.
- Microsporum gypseum : it develops in the ground and mainly affects dogs who like to dig at the level of the head.
Ringworm is extremely contagious, transmission occurs through direct contact with an animal with ringworm or from the environment.
Ringworm is a zoonosis, that is to say, it can be transmitted to humans: red skin lesions appear on the areas in contact with the animal.
Ringworms are much less common in dogs than in cats. Special consideration should be given to ringworm in dogs that live with cats. Please note that cats can be asymptomatic carriers: the possibility of ringworm should not be excluded if the cat has no symptoms. We invite you to read our fact sheet on ringworm in cats for more information.
Yorkshire terrier dogs are predisposed to this disease: ringworm quickly reaches the whole body.
What are the symptoms ?
In dogs, ringworm usually causes loss of hairs with a rounded shape, with some dander. Dogs don’t scratch and there is no redness in terms of hair loss. They can heal spontaneously or the lesions can get larger.
More rarely, ringworm can lead to red lesions of rounded shape, in relief, very itchy, oozing, suppurative …
Finally, there are dogs that do not show symptoms, they are healthy carriers.
The veterinarian will first ask several questions: the presence of other animals in the home? age and provenance of the animal (breeding, refuge, individual)? presence of lesions in the owner? etc …
A thorough clinical examination will be carried out by the veterinarian to see if the animal has hair loss, dander, redness …
Additional examinations can then be carried out:
- Direct observation of hairs under the microscope by the veterinarian
- Use of wood lamp : some strains of Mr canis produce a substance, pteridine, which becomes fluorescent with Wood’s lamp (UV lamp). Please note that only certain strains of Mr canis synthesize this substance and other fungi do not synthesize it: the absence of fluorescence therefore does not eliminate the hypothesis of ringworm. This method also does not allow to identify asymptomatic carriers and this examination must be carried out before any antifungal treatment
- Cultivation of hairs : results are obtained after several days to several weeks only
What treatments are needed?
It’s a parasitic disease very difficult to eradicate : highly contagious disease, resistance of the fungus in the environment, existence of asymptomatic carriers …
It is sometimes necessary to trim the coat of the animal if it has long hair, if the ringworm spreads or recurs, etc …
A local treatment may first be prescribed by the veterinarian, it is an antifungal lotion.
Antifungal tablets may also be prescribed for the animal, this is a systemic treatment. Treatment lasts several weeks, most often 4 weeks or more depending on the course of the lesions. The treatment is long : the animal must no longer have ringworm lesions and a culture must show the healing of the animal.
The environmental treatment is very important but also very difficult. Several products are necessary: bleach, fungicidal candles (on veterinary prescription), etc.