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canine health problems

Here’s how to identify and treat ringworm in dogs

Ringworm in dogs is a fungus similar to athlete’s foot in humans

Updated September 10, 2021

Created By

Christy Caplan, CVT,

The essentials 

  • Ringworm (dermatophytosis) is caused by fungi It can affect a wide range of species and is highly contagious.
  • Animals can be treated with antifungals, ointments, lotions, and dips to shorten the course These also prevent your pet from spreading ringworm to other animals or people.
  • Typically animals that are stressed, sick, older, or weakened will suffer from severe or more widespread infestations The condition “typically” looks like circular gray patches.

What is ringworm? 

Ringworm, also known as dermatophytosis, is a superficial skin infection that affects the hair, nails, and coat. Dogs may be itchy, but you often see hair loss, scaliness, scabs, and crusty areas. This fungal infection may impact dogs with weakened immune systems.

Ringworm isn’t a “curly” worm but a fungus

Ringworm isn’t a worm but a plant-like growth that lives on the surface of the skin — It gets its name from how it looks. It will typically have a “ring” appearance, but many times there’s no ring at all, and instead, you’ll see only bald spots or red and crusty lesions. So don’t always rely on just the ring when suspecting your dog may have ringworm.

Ringworm can pass from animals to humans

A zoonotic disease is an infectious disease transmitted between species from animals to humans (or from humans to animals). For example, humans can pick up ringworm from dogs and vice versa. Children should avoid handling a dog diagnosed with ringworm and shouldn’t have direct contact. Dogs treated with an antifungal drug will get rid of the active infection in hair follicles, and topical therapy disinfects the skin and hair coat.

Ringworm affects a wide range of animals — The majority of cases and the primary fungi that are zoonotic are the Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes.

It may also live in the soil

Ringworm may be a concern if you frequently visit the beach where other dogs spend time. Your pup may get this disease from digging in the soil or sand where ringworm spores live.

👉 The Trichyphyton fungi live in dirt while the Microsporum spp. lives on animals.

How do I get rid of ringworm on my dog?

Treating this skin problem will speed up healing and also help protect your human family from getting ringworm! There are a variety of treatment plans your vet will walk you through. For example, a mild case may only require a topical medication (like a lotion), while more extensive cases may need two to three different medicines, including a dip.

Does it go away on its own?

The American Kennel Club Canine Health Foundation says treatment will help eliminate the contagious aspects of this disease and speed up recovery. As the fungus grows in the skin cells and hair, the skin may become irritated. Treating this disease as soon as possible is essential, and if ringworm covers most of your dog’s body, it’s a very serious problem.  

👉 After contact happens, the fungus attaches to a dog’s skin, hair, or toenails. The signs of infection can develop within 1 to 3 weeks.

Clinical signs and symptoms

A rapidly spreading circle with hair loss at the center and a red ring at the edges is how ringworm sometimes appears. It will typically have this “ring” appearance, but many cases have no ring at all!

They can look like bald spots or red and crusty lesions. Look for the following skin issues:

  • A circular or ring-shaped swelling
  • Bald patch in multiple locations on the dog’s hair coat, or one single location
  • Scales and crusts, patchy rashes with reddening or darkening of the skin
  • Itching, scratching, and licking

Ringworm often resembles demodectic mange or dry seborrhea

Thankfully, the symptoms of skin disorders are easy to detect compared to other health issues. Hair loss and local scaliness often resemble mild cases of ringworm but may be mange. With that in mind, if you see the above symptoms, a diagnosis by your vet is simple and isn’t invasive for your dog.

Help your vet rule out other possible skin issues

Your vet will conduct a few tests to confirm ringworm is the final diagnosis. Sometimes it’s misdiagnosed because it looks like other skin infections. However, a positive fungal culture test can confirm infection. Here’s some important information to write down before you head into the vet.

  • Has your dog been near another animal or human with ringworm?
  • Has your pup been in close contact with other dogs?
  • Are there signs that are compatible with ringworm?
  • Is there another infection or disease that could be causing your dog’s symptoms?

Narrowing the diagnosis is important

Your vet may diagnose the species of this fungus with a “Wood’s lamp” as they glow under a type of black light. A Wood’s lamp emits ultraviolet light to detect bacterial or fungal skin infections. Yet less than 50% of ringworm patients fluoresce with the lamp.

Vets prefer fungal cultures or PCR (DNA) testing. With just a hair sample, this highly sensitive test produces results in just 3-5 days! Trichograms (the evaluation of hair under a microscope) are another way to get an accurate diagnosis, as a hair sample under a microscope may produce evidence of ringworm fungi. The popular and precise tests include:

  • PCR Testing
  • Fungal cultures
  • Trichograms

Treatment plans vary

Some dogs may only have a few small lesions on their skin compared to generalized ringworm, which is more serious. Your dog’s overall condition determines the type of treatment. You may need to use a “dip” which uses water to deliver various antifungal agents to a dog’s skin. This product is similar to shampoo. Treatment plans may include one or more of the below medications (oral or topical) or a special dip.

  • Fluconazole oral medication. May be given as directed
  • Topical miconazole. An easy to apply lotion, is used for small focal lesions
  • An over-the-counter (OTC) Lime Sulfur Dip. May be applied according to directions on the label to the lesions, typically twice a week. It smells and stains! You use this dip on ALL the pets in the house.

A clean bill of health is when your vet obtains two negative fungal cultures at least 3 weeks apart. This means your dog is treated for 6 weeks, depending on the severity of the illness.

Even with a mild case, you’ll be asked to return in 3 weeks for a recheck and another fungal culture, then likely another 2 weeks after that.

👉 Always be sure to check with your vet before using any specific OTC products.

Our favorite ringworm dip: Classic’s Lime Sulfur Dip

This lime sulfur dip must be diluted and used according to the instructions on the label. Dips use water as a way of delivering various antifungal agents to the skin. After the hair is clipped, using cleansing baths helps to obtain greater penetration in animals with excessive scale or crust.

Once you’ve used the dip for ringworm, it’s best to put your dog in a crate as it stains carpets and blankets. However, the product is highly effective in treating ringworm. It’s important to always check the label on any topical agent.

Ingredients 
97.8% sulfurated lime solution, 2.2% inert ingredients

Environmental decontamination and prevention 

Cleaning your home and dog’s toys, crate, brushes, food bowls, and bed is equally as important as the treatment plan for your pup. Infective spores are contained within your pet’s hair, so removing as much hair as possible from the environment needs to be your goal.

Get out the vacuum — Frequent vacuuming is recommended.

Steam clean upholstered furniture and carpets — This will help remove even more hair, but doesn’t kill infective spores.

Use concentrated chlorine bleach (0.5-5% sodium hypochlorite) — One of the few household chemicals for eliminating fungi within hairs. Since concentrated bleach is not practical for household use, use a 1:10 dilution (1 part bleach, 9 parts water).

Keep your pet in one area — If possible, infected animals should be kept in an area of the house that can be safely cleaned with bleach.

A personal warning about ringworm

Christy Caplan, CVT and writer for betterpet, had her own first-hand experience with ringworm on her dog Walter. He was finally done with his puppy vaccinations, and she took him to a popular beach shortly after the last booster. Unfortunately, Walter ended up with ringworm and the lime sulfur dips weren’t fun for him or her! Even with the treatment plan, it took around 8 weeks for the ringworm to completely resolve.

Ringworm overview 

A veterinarian will need to determine and rule out ringworm infections with a number of vital diagnostic tests. The treatment plan may include medicated ointment, cream, or medicated shampoo (a.k.a. dip). Always suspect ringworm when you see circular patches of hair loss or red lesions as these are primary symptoms of ringworm. The diluted bleach solution will help decontaminate household items with fungal spores.

If your dog is showing signs of ringworm — don’t fret. It’s a very treatable condition with a treatment plan from your pup’s vet. Follow their instructions very closely so your furry friend can be ringworm-free! Just remember to be patient and diligent as ringworm can take 6 to 8 weeks to resolve depending on the severity of your dog’s infection.

Frequently asked questions

Can ringworm be fatal?

No, ringworm isn’t fatal but it can be very uncomfortable for puppies and senior dogs. A generalized infection that covers the body is serious and needs to be treated by a vet.

What home remedy kills ringworm on dogs?

There are herbs a holistic vet may recommend yet natural solutions for ringworm are not as effective as medications prescribed by your veterinarian.

What over-the-counter medicine can I use for ringworm on my dog?

Over-the-counter medicine may include a Lime Sulfur Dip and your vet will recommend the variety of brands available at the clinic or online. Always follow the instructions on the label.