Ring worm in dogs

The ring worm is a highly contagious superficial fungal infection of the skin, scalp, nails, feathers and hair affecting all species of animals and man. Ringworm also known as dermatophytosis is the most common zoonotic disease transferred from animal to humans and is found in all part of the world, specially in hot and humid areas. Ring worm is caused in dogs by Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes.

Which dogs are more susceptible to ringworm?
Young dogs and puppies are more susceptible to ringworm. It is also highly susceptible in dogs with under developed or weak immune systems


Which dogs are more 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.


How is ring worm transmitted in dogs?
The ring worm is transmitted by the following
(a) Direct contact with the infected animal
(b) Indirect contact with fomites such as grooming kit, bedding's etc
(c) Dogs carry the on the healthy skin and transmits it to be susceptible animal
(d) Ringworm may also be transmitted through contact with infected soil or other organic materials.

What are the signs and symptoms of the ring worm?
The incubation period is 10-12 days, that is, about 10-12 days will pass before any lesions occur following exposure to the ring worm. Infected dogs remain contagious for about three weeks. In the dog, the skin lesion are mostly found in the face, legs, feet, tail and lower abdomen. The dog shows signs of itching and patches of hair loss can be seen in the dog. The skin lesion in dogs appear at first as pink spots or blemishes in the skin that are neither raised nor depressed. As the disease advances the lesion appear as circular up to 3 cm in diameter and covered with grayish scales in the center. However, these skin lesions in dogs are not always circular in shape. They can be spotted, oblong or oddly shaped Small pustules are often found in the lesion. Secondary bacterial infections or mite may invade the lesion which aggravates the condition and produces multiple lesions on shoulder, back and neck of the dog.

How is ring worm diagnosed?
Diagnosis of ring worm depends upon characteristic lesions. But for confirmation and determination of specific dermatophyte the following is done
(a) Microscopic examination- Skin scrappings, hair, nails etc with 10%KOH solution is examined under microscope.
(b) Cultural examinations- Clinical materials from suspected dogs are cultured on suitable media.
(c) Wood’s lamp- Ultraviolet rays are used
(d) Skin test- The fungal antigen at a rate of 0.1 ml is given sub cutaneously and the reaction is checked after 24-48 hours.


How is ring worm treated in dogs?
Clip the area close to the skin leision. Treatment of ring worm is in the following way:
(a) Anti fungal drugs- Griseofulvin at a dose rate of 7-20mg/kg body weight for 14-50 days
Thiabendazole at a dose rate of 2-5.5mg/kg body weight
Ketoconazle at a dose rate of 10mg/kg body weight orally
Nystatin at a dose rate of 10,000 IU/lb body weight
(b) Topical ointments like Lotrimin cream, 2% Miconazole cream, 1% Cotrimazole
(c) Antifungal shampoos or dips like 2% Miconazole shampoo, Ketoconazole, 0.5% Chlorhexidine, lime sulfur dips. Dips should be given twice a week and can be performed either by your vet or at home


How to prevent and control ring worm in dogs?
Currently there are no reliable vaccine against ring worm in dogs. To prevent and control ring worm the following must be practiced:
(a) Identification and isolation of infected dogs
(b) Clean and disinfect grooming kits, bedding's etc with bleach solution

Can man get the ring worm from dogs?
Yes, man, specially children can be infected with ring worm from dogs by touching, grooming or petting dogs. Ring worm may be passed from dogs to man and also from man to dogs.


What to do if your house has ring worm fungus?
Fungal spores live in the carpet, bedding and premises for several months. Disinfect the premises cage or kennel and all contaminated objects with bleach mixed at 1:10 on any surface that you can. One can also use 5%phenol or 2% formaldehyde, or 1% caustic soda.

Why does ring worm reoccur in some dogs after successful treatment?
Ring worm occurs in dogs sometimes after successful treatment in cases when the treatment is not long enough or aggressive enough to kill the fungus. It also reoccurs in dogs with under developed or weak immune systems.