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Ringworm in Dogs: Symptoms, Causes, and Treatment

Are you battling ringworm? Don't despair! With proper care and commitment, victory is within reach. Check out this blog post for all you need to know about ringworm in dogs: symptoms, causes, treatments, and more!

Written by Raquel Astacio. Published in February 2023.

If your dog has developed an abnormal rash made up of strange, circular-shaped lesions, it may be time to talk about ringworm - an infectious fungal condition that can affect both humans and animals alike.

When caught early, ringworm is mostly harmless and easy to treat. But our four-legged loved ones will be much safer if we know what to watch out for, as well as how to diagnose and treat this infection. In this blog post, we'll cover everything pet parents need to know about ringworm - symptoms, causes, treatments, and more. Let’s get started!

What Causes Ringworm in Dogs?

Ringworm is a highly contagious type of fungal skin infection that causes ring-shaped lesions to appear on a dog’s skin. Though ringworm is most commonly seen in domestic animals such as cats and dogs, it can also affect humans.

Ringworm has a deceptive name because it is not actually caused by any sort of worm or parasite. Instead, its moniker comes from the characteristic circular red rash seen on those infected.

Ringworm infections are caused by species of fungi called dermatophytes, which have remarkable capabilities. Some dermatophytes can only affect one species, while others are easily spread between animals and humans (as is the case with ringworm). Dermatophytosis is the formal medical name for this type of infection.

How is Ringworm Transmitted?

Ringworm is highly contagious and can be spread in one of two ways: through direct contact with an infected animal or person or through shared contact with contaminated items like brushes, food bowls, bedding, furniture, and even carpet. Environmental contamination can be especially aggravating because ringworm spores can survive on a shared surface for up to eighteen months at a time.

Symptoms of Ringworm in Dogs

Though ringworm is not a life-threatening condition, it is highly contagious and can easily be spread from dogs to humans - and vice versa! Because of this, pet owners should familiarize themselves with the first warning signs of ringworm so that it can be caught early on and stopped before others become infected.

A dog with ringworm will usually develop small, circular patches of hair loss throughout their coat. This is the first sign of infection. These lesions, which tend to start small and grow larger over time, can become red or inflamed and will begin to heal from the center outward - giving them a patchy appearance that is entirely unique to this type of infection.

In addition, a dog with ringworm may also develop the following signs:

  • Dry or brittle hair
  • Scabby, inflamed, or irritated skin
  • Brittle or misshapen toenails
  • Darkened patches of skin
  • Itchiness or excessive grooming
  • Patches of heavy dandruff

As a rule of thumb, pet parents should diligently monitor for any changes in their dog’s coat. Though ringworm is certainly one of the more common fungal infections out there, changes in your pup's skin or coat may also be indicative of something deeper brewing beneath the surface, like Cushing’s Disease. And if systemic issues can be ruled out, it’s also possible that your canine companion is struggling with allergies or another skin-related issue that requires attention.

How is Ringworm Diagnosed in Dogs?

There are various ways in which ringworm can be diagnosed, starting with a visual assessment.

What Does Ringworm Look Like?

Most veterinary professionals are able to identify ringworm solely by its unique appearance. In dogs, ringworm creates small lesions on the skin that are ring-shaped or circular. These distinctive lesions are typically raised from the skin's surface and possess a scaly texture. They will also often turn bright red in color towards the outer edge.

But if a visual examination is inconclusive, your veterinarian may recommend additional testing using one of the following methods:

  • Examining skin scrapings under a microscope to check for the presence of ringworm fungus.
  • Submitting a sample of the affected area for a fungal culture.
  • Examination of the affected skin areas with a Woods Lamp, which causes ringworm to become fluorescent under ultraviolet light.

In some cases, additional blood tests may also be carried out if an underlying condition is suspected, though blood work is not generally required for ringworm diagnosis.

How to Treat Ringworm in Dogs

When treating a dog with ringworm, owners should be sure to follow the necessary treatments, quarantine measures, and cleaning instructions outlined in the following section, along with any additional recommendations made by their vet.

Quarantining Infectious Pets

If you suspect your dog may have ringworm, the first step you should take is to quarantine your pet away from other family members - animals and humans alike! Ideally, ringworm-positive pets should be isolated ​​in a room that can be easily disinfected, such as a spacious bathroom. Infectious pets should also avoid contact with carpets, wood floors, and other surfaces that are difficult to sterilize properly.

Topical Treatments for Ringworm in Dogs

Bathing your pet is a crucial component of ringworm treatment, as it effectively eliminates the fungal spores on a dog’s fur and reduces environmental contamination. For optimal effectiveness in treating ringworm, owners should consider giving their pet a lime sulfur dip, though these should ideally be conducted at veterinary offices due to their messiness and strong odor. Alternatively, using a disinfectant solution such as Chlorhexidine paired with shampoo will also help combat the fungus growth.

Oral Treatments for Ringworm in Dogs

By using oral antifungal medications in combination with topical treatments, you can help your pet overcome ringworm infection. Your veterinarian will work closely with you to select the best medication for your specific situation and budget - but do keep in mind that there may be some gastrointestinal side effects associated!

Some of the most popular oral medications used to treat ringworm in dogs are Itraconazole, Griseofulvin, and Terbinafine. While treatment times may differ from pet to pet depending on severity, a minimum six-week course should typically be observed - especially since early discontinuation can lead to recurrent bouts of infection.

Decontaminating Your Pet’s Environment

Dogs who have been infected with ringworm are constantly shedding invisible fungal spores onto their surroundings. And because these fungal spores are impossible to see with the naked eye, they are incredibly hard to get rid of. That’s why infectious dogs should always be kept in isolation, away from other people and pets, until the infection clears.

Additionally, pet owners should be sure to keep other areas of the home disinfected using an appropriate sanitizer, such as diluted bleach. And for maximum effectiveness, owners should be sure to clean any and all surfaces thoroughly prior to applying a disinfectant solution - so that we leave no room for contamination from these potentially troublesome fungal spores!

How to Prevent Ringworm in Dogs

It is important to remember that pets, who can be asymptomatic carriers of ringworm, may still have the infection even if no symptoms are present. Because of this, it's important to get all your four-legged family members tested following a single positive diagnosis in the household.

The best way for pet owners to prevent their dogs from contracting ringworm is to develop a thorough understanding of how and where this infection spreads. Ringworm is a highly contagious infection that can be passed between humans and their pets. To reduce the risk of it spreading, make sure to visit your doctor if you notice any red circular skin lesions on yourself or your pet.

It's also important to keep any stray animals isolated from your pets until they have been examined by a veterinarian, as ringworm can quickly spread through the soil in areas populated with wildlife.

FAQs About Ringworm in Dogs

“How long does it take for ringworm to clear up in dogs?”

Treatment for ringworm in dogs generally lasts multiple weeks and should not cease until follow-up testing shows there aren't any traceable fungal organisms left.

“How long is ringworm contagious in dogs?”

Ringworm in dogs is contagious until about three weeks after the start of aggressive treatment. During this time frame, your veterinarian will likely recommend that you reduce exposure between both animals and humans living in your home.

“Is ringworm in dogs contagious to humans?”

Ringworm is a zoonotic skin infection that can be transmitted between both animals and people. And while ringworm can affect any person, regardless of age, gender, or race, some people are more susceptible to ringworm infections than others.

Groups considered especially high risk for ringworm transmission include the following:

  • Young children with still-developing immune systems
  • The elderly whose immunity naturally declines as they age
  • Pregnant women
  • Those undergoing chemotherapy or other immunosuppressive treatments which can further weaken their bodies' natural defenses against infection

“Will ringworm go away on its own?”

While ringworm may eventually go away on its own due to natural resistance from your dog’s immune system, there is no guarantee that the infection won't spread during this time period - not only putting your pet at risk but potentially passing on the infection as well if precautions are not taken. To protect everyone involved, prompt medical attention should be sought out for a safe resolution to any potential outbreak.

“Are there any home remedies for ringworm in dogs?”

Before trying to treat ringworm with home remedies, it's important to be aware of the potential consequences. At-home treatments may offer a false sense of security as they are often ineffective and can even prove toxic for pets if used incorrectly. Over-the-counter antifungal shampoos may offer some relief, though nonprescription medications should be used with caution since their effectiveness is uncertain.


There are a lot of things to despise about ringworm - it’s highly contagious, tough to get rid of, and can cause significant discomfort for your pup! But the good news is that ringworm is also a treatable condition. With proper care and treatment, you can help prevent the spread of ringworm and ensure that your dog makes a full recovery - so that he can spend less time scratching and more time with the people he loves!

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