Key takeaways

Ringworm in dogs is a contagious fungal infection that appears as scaly or flaky areas of hair loss, and can be transmitted through direct contact or contaminated objects.
Effective treatments for ringworm in dogs include topical antifungal creams, medicated shampoos, and, in severe cases, oral medications, with treatment duration often lasting a minimum of six weeks.
Diagnosis of ringworm involves a physical examination, fungal culture, and possibly the use of a Wood’s lamp, highlighting the importance of consulting a veterinarian for accurate diagnosis and treatment.
Prevention of ringworm in dogs involves maintaining good hygiene, isolating infected pets, and ensuring new pets are checked by a veterinarian to prevent the spread of the infection.

What is ringworm? | Symptoms | Treatment | Prevention

Dogs are our best friends. We take care of them for their entire lives and, in return, dogs love us pretty much unconditionally. Unfortunately, our furry companions are susceptible to some of our same health conditions. One of these is ringworm, also known as tinea, dermatophytosis, or microsporum canis.

What is ringworm?

Ringworm is a fungal infection of the skin. In humans, it appears as an itchy, circular, red rash. It can be transmitted by touching contaminated surfaces or person-to-person. It commonly affects feet (called athlete’s foot), and the groin area (known as jock itch). It’s common in athletes due to their prolonged periods in sweaty clothes. It can also occur on the hair and nails. There are many over-the-counter and prescription treatments for ringworm in humans. In dogs, there are several other considerations.

Causes

“The fungus responsible is called a dermatophyte, and it consumes the keratin of the skin and hair, resulting in patches of hair loss on dogs and cats as the infection spreads,” says Megan Conrad, BVMS, a veterinarian with Hello Ralphie. Keep an eye out for these patches.

“Ringworm is most common in puppies (and kittens) or in dogs with a weakened immune system,” says Sarah Wooten, DVM, CVJ, a veterinary expert for Pumpkin Pet Insurance. However, it can occur in any dog.

Dogs can contract ringworm from the environment where it lives in warm moist soil, from food bowls, dog beds or brushes, or it can be passed along directly from other infected animals. “Rarely, a dog can be a carrier without ever showing symptoms of ringworm and end up spreading it to other animals and humans,” says Dr. Conrad. “One of the most common causes of ringworm seen in practice is owners introducing new animals into their homes such as puppies and kittens that may carry the fungus and pass it on to their other pets or owners.”

Is it contagious?

Ringworm in infected dogs, like in humans, can be passed through direct contact. Sometimes “it may be species-specific meaning that it isn’t contagious between different species,” says Chyrle Bonk, DVM, a veterinarian working with Hepper. Other types of ringworm can be transmitted across species.

Its ability to move from creatures and on surfaces makes it even more contagious. “Ringworm is very contagious because the infection does not have to take place from infected animal to animal, it can also be spread through objects that have been contaminated by an animal or human with ringworm,” says Brian Evans, DVM, of Dutch. “Ringworm can also live on untreated surfaces for up to 18 months.” To avoid reinfection, clean all contaminated objects with a disinfectant. Fungal spores can stick to objects like dog brushes and combs, food and water bowls, furniture, carpet, and bedding. It can be difficult to remove ringworm spores from the environment. Try vacuuming, steam cleaning carpets, washing affected laundry twice, and using a diluted bleach solution for surfaces.

What does ringworm look like in dogs?

While ringworm in dogs might look similar to how it does in humans, ringworm doesn’t have to come in the typical raised ring shape. It can be irregularly shaped and may present as scaly or flaky areas of hair loss surrounded by brittle, broken hairs. Dr. Wooten adds that it commonly appears on the muzzle. Other common areas include the abdomen, inner thigh, and toenails.

“Claws can also become infected and can result in them becoming rough or broken off,” Dr. Evans says. Keep up with regular nail trimmings to help keep nails healthy and to watch for signs of ringworm.

How to treat ringworm in dogs

If you suspect your dog has contracted ringworm, it’s best to have it looked at and treated, rather than wait and see. “There is a chance that ringworm can go away by itself, but this will be at the cost of your dog’s well-being,” says Dr. Evans. “They will experience symptoms for a longer amount of time than necessary as opposed to if they received proper medical care.” Untreated ringworm in dogs can take nine to 12 months to go away, but that’s a long time for your dog to be uncomfortable. Since ringworm is contagious to humans and other animals, waiting a year for it to go away on its own is not a good plan.

How is ringworm diagnosed?

Don’t try to diagnose and treat ringworm without an appointment with your vet. The doctor will do several tests to confirm the diagnosis of ringworm—and rule out other similar skin conditions. Bacterial skin infections, mite infections, and allergic skin diseases can look very similar so it is important to have the correct diagnosis before beginning treatment. After your vet determines that ringworm is the cause they can advise you on the best course of treatment.

“Ringworm is usually diagnosed with a physical examination of the dog’s skin, fungal culture and/or with a light called a Wood’s lamp,” says Dr. Conrad. A Wood’s lamp emits black light of a specific ultraviolet light frequency that makes infected hairs glow a green color. It’s not a definitive diagnosis, but can be one of several clinical signs.

“The gold standard in diagnosing ringworm is a fungal culture,” says Dr. Wooten. “These can take several weeks to grow which is why a Wood’s lamp can come in handy.” If the Wood’s lamp shows signs of a fungus, your vet may prescribe medication until the culture results come back.

Treatment medications

Like human antifungal meds, there are over-the-counter topical treatments for mild cases of ringworm in dogs. There are creams, ointments, and medicated shampoos applied to the affected area. Your vet may also give you a prescription-strength treatment.

Drugs used to treat ringworm in both dogs and humans include:

If topical therapy fails, oral medication might be necessary.

Treatment procedure

Follow your vet’s instructions about how best to treat your dog’s specific ringworm as different presentations and parts of the dog’s body will require different treatment. “If there is one lesion, it is recommended to clip the dog’s hair widely around the lesion (then disinfect the clippers because remember—contagious!) and apply a topical antifungal cream every 12 hours until the lesion resolves,” says Dr. Wooten.

However, Dr. Wooten continues, “If the dog has generalized ringworm or a bad ringworm infection in their nail beds, then the story is different. It is recommended to clip the entire haircoat and utilize both a topical antifungal rinse and oral antifungal medication. This always involves the help of a veterinarian.” Your vet may use a medicated solution to kill the ringworm fungus. Do not try to treat generalized or nail ringworm at home. It’s dangerous for your pet!

How long does it take to recover?

Like most illnesses and conditions, recovery depends on severity of the case and adequate treatment. “Recovery from ringworm depends on a case-by-case basis but usually treatment goes on for a minimum of six weeks,” says Dr. Evans. As you’re treating, keep in mind that, “It stays contagious for the first few weeks after treatment begins, and almost indefinitely without treatment.” You will need to keep infected pets away from others.

How to prevent ringworm in dogs

Fortunately, with good hygiene and vigilance, you can prevent ringworm in dogs or keep your dog safe if another pet or person has an infection.

Keep others safe

If your dog has ringworm and you want to prevent infecting other animals or people, “Ultimately a negative fungal culture is necessary to determine if your dog is free of the infection,” says Dr. Conrad. Isolate your pet until you have confirmation.

To prevent spreading to other animals in the house if one of your dogs has ringworm, “It is also recommended to rinse other pets (dogs and cats) in the household with an antifungal rinse weekly even if they don’t have any signs,” says Dr. Wooten. Better safe than sorry. Your veterinarian can advise if an antifungal shampoo or rinse is needed and prescribe one for other pets in the house.

In the community

To keep your dog from contracting ringworm when you know there are cases in your community, “Don’t let your dog interact with people or animals with ringworm and especially do not let them around areas you know could have been contaminated,” says Dr. Evans. “Be aware of any patches of hair loss as well so you can receive treatment as early as possible if they become infected. Keep their bedding, toys, and collars clean, especially after interacting with unknown dogs at the park for example.”

When your dog is in someone else’s care—like at a boarding or kennel facility, “ask about sanitation protocols for infectious diseases,” says Dr. Wooten. Similar to how you’d expect a gym or hotel to be clean and sanitized between visitors, demand the same for your furry companions.

New pets

If you get a new pet, you can prevent a ringworm infection in your house by getting your new pet checked right away. “It is important for all new animals introduced into the home to have an exam with a veterinarian shortly after adoption for a full check over,” says Dr. Conrad. Not only does getting a checkup prevent ringworm from entering your house, but it is the recommended course of action for any new pet to make sure the new pet is healthy and doesn’t bring any other infections home.