Ringworm is a common skin disorder that affects almost all domestic species—including dogs and cats, but it’s actually not a worm at all. 

Ringworm is a highly contagious fungus. Because of this, it’s important to identify and treat ringworm in dogs quickly to keep pets and people in your household healthy. 

What Is Ringworm?

Ringworm in dogs, also called dermatophytosis, is an infection of skin, hair, or claws caused by a type of fungus. 

In dogs, about 70 percent of ringworm cases are caused by the fungus Microsporum canis, 20 percent by Microsporum gypseum, and 10 percent by Trichophyton mentagrophytes, an infection, named for its circular ring-like appearance, that resembles a coiled-up worm.  

The fungus thrives in the outermost layer of skin and in the hair follicles of infected dogs, and sometimes even in the nails. Young dogs, senior dogs, and dogs with compromised immune systems are more susceptible to ringworm infections.

Can You Get Ringworm From Dogs?

People and other pets can contract ringworm from infected dogs. It is zoonotic, which means it can be transmitted to people from animals. Elderly people, children, or anyone with immune problems have a higher risk of contracting the infection.

In humans, ringworm presents as a roughly circular rash that is often red and itchy. If you or a family member notices a rash on your body after your dog has been diagnosed with ringworm, contact your primary care physician.  

Symptoms of Ringworm in Dogs

Ringworm often causes a circular raised rash on the skin of dogs, but a ringworm infection can manifest in many ways. 

Some symptoms of ringworm in dogs include:

• Circular areas of hair loss
• Dry, brittle hair
• Skin crusts
• Scabby or inflamed skin
• Infection of the nail beds or brittle nails 
• Acne-like bumps on the skin
• Abnormal appearing skin or hair loss on the face, ear tips, tail, or paws

If you notice any suspicious areas of hair loss, redness, crusts, or lesions on your dog, have them checked out immediately.

How Do Dogs Get Ringworm?

Ringworm in dogs spreads through direct contact with the fungus. This can happen when a dog comes in contact with an infected animal or person or touches a contaminated object like furniture, carpets, or grooming tools.  

The fungal spores responsible for the spread of ringworm can remain viable for up to 18 months and typically spread through shedding or breaking of infected hairs. Dogs that visit grooming facilities, doggie day cares, boarding facilities, or pet stores frequently are at higher risk of contracting the infection. 

Ringworm is rare in healthy animals that live at home. Shelters will occasionally see outbreaks of ringworm infection because of the high number of unhealthy animals entering their facility. 

Some types of ringworm spores are found naturally in the soil. Others are carried by rodents. Contact with any source of a fungal spores can cause ringworm in your dog.

Diagnosing Ringworm in Dogs

Your veterinarian will need to perform a few diagnostic tests to confirm or rule out ringworm. 

First, a physical examination is necessary to assess your dog’s overall health. Their general health is an important indicator, as there are other diseases that can cause secondary skin issues, such as hypothyroidism, allergies, and Cushing’s Disease.  

Ringworm may be diagnosed by evaluation with an ultraviolet lamp, where a fungus-coated hair will glow with a yellowish-green color. The hairs that light up are then examined under a microscope for specific spores and other fungal characteristics. However not all ringworm infections will glow.

Performing a fungal culture of hairs and analyzing scrapings from the affected areas is the most accurate method of diagnosing ringworm in dogs. It can take up to four weeks to get the results. 

How to Treat Ringworm in Dogs

If your veterinarian diagnoses your dog with ringworm, there are a few treatments that may be prescribed.  

Ringworm treatment will involve oral medications and environmental decontamination and many also include topical antifungal medication. You may need to apply prescription cream or lotion to any lesions on your dog’s skin. In dogs, topical treatments can only be used in locations that your dog cannot lick. If this is a recommended treatment method, make sure to wear gloves to avoid the spread of spores. 

Ringworm in dogs is often localized, meaning it usually occurs in small areas of the body, so full body dips are not usually necessary. However, full body dips may be used for severely affected dogs or those who cannot tolerate oral antifungal medications.

Common Ringworm Medications for Dogs

Medications used to treat ringworm in dogs include:

• Itraconazole (oral)
• Fluconazole (oral or topical)
• Terbinafine (oral or topical)
• Clotrimazole (topical)
• Lime sulfur dips
• Enilconazole dips
• Miconazole shampoos
• Ketoconazole shampoos
• Climbazole mousse

It will take at least six weeks of repeated treatments to completely cure a ringworm infection. In some instances, it may take longer. Do not stop treatment unless it is recommended by your veterinarian, as cutting treatment short can result in a recurrence of the infection.  

Your veterinarian may also recommend treating other pets in the household, even if they do not show signs of a ringworm infection.  

If left untreated, ringworm in an otherwise healthy dog may resolve on its own. But it may take nine months to a year to do so, putting people and pets in your household at risk.  

Deep cleaning the house is just as important as giving your dog his prescribed medications. Repeated vacuuming will help to remove loose fur carrying fungal spores. Clean all hard surfaces with bleach. Anything that can be washed in the washing machine and dried in the dryer should be. Treating the pet and not the house will result in recurrent infections or spread of the infection to other pets and people. 

Cost of Ringworm Treatment in Dogs

If the ringworm infection is contained to only a few lesions, cost of treatment may come in under $100 for an initial veterinary examination and topical ointments or prescription antifungal medications. 

But more serious cases of ringworm can be much more difficult to treat and may cost upwards of $500 for an examination, diagnostics, and long-term treatment plans. No matter the cost, treating the ringworm appropriately is worth the safety of your dog and family.

Ringworm Precautions in Your Home

During treatment, it is also important to keep your home and your dog’s environment clean. 

Fungal spores can be killed with a solution of chlorine bleach and water using the dilution of one pint of chlorine bleach (500 ml) in a gallon of water (4 liters).  

Infected pets remain contagious for about three weeks if aggressive treatment is used. The ringworm will last longer and remain contagious for an extended period of time if only minimal measures are taken or if you do not follow your veterinarian’s prescribed treatment plan. 

Minimizing your dog’s exposure to other dogs or cats and to your family members is recommended during this period.   

How to Prevent Ringworm in Dogs

Besides keeping your dog away from other pets or people infected with ringworm, there is not much you can do to prevent ringworm in dogs. 

You can speak to the managers of any facilities your dog frequents, such as doggie day care or grooming salons, and ensure that there has not been a recent history of ringworm there.  

Keeping your home and your pet’s areas clean are essential steps in preventing the spread of ringworm. Regularly disinfect your dog’s toys, food bowls, bedding, blankets, and grooming supplies to kill spores. Keep the environment clean by vacuuming carpets, furniture, and areas of the house that your dog frequents. Disinfect all areas of the house that your dog and other pets use frequently.

Hopefully, with a clean, happy, healthy house, and a bit of luck, you and your dog will never experience a ringworm infection.