- Dr. Nicole Bertolini
- Jan 22
- 4 min read
A common misconception is that ringworm is truly a worm, however, ringworm is actually a fungal infection that creates a raised circular lesion within the skin. In dogs, this infection can affect the skin, hair follicles, and sometimes the nails.
This disease can be alarming for pet owners as it’s highly contagious to pets and humans. Knowing its causes, symptoms, and available treatments is essential for avoiding a hairy situation for your furry companions and family.
Symptoms of ringworm in dogs: recognizing the signs
Ringworm in dogs often manifests itself in distinct ways, this can include:
Circular patches of hair loss
The skin within the circular area may appear red, scaly, or inflamed
Scratching or licking the affected areas (though many dogs show no discomfort)
Distorted or brittle nails if the fungus spreads to the nail bed
Ringworm can spread across a dog's body
While these lesions frequently appear on a dog’s head, ears, limbs and paws, they can develop anywhere on the body. Ringworm can be harder to spot on your long-haired dog and may spread before you realize it. If you notice any unusual spots or hair loss on your pet, it’s always best to seek a veterinarian’s advice promptly.
Causes of ringworm in dogs
Why dogs get ringworm: fungi
Three types of fungi are commonly responsible for ringworm infections in dogs:
Microsporum canis (most common)
Microsporum gypseum
Trichophyton mentagrophytes
These fungi thrive in hair follicles and the superficial layer of the skin.
How dogs get ringworm infection
Dogs can contract ringworm in several ways. Coming into direct contact with an infected animal is the most common way. Young dogs, free-roaming animals, hunting dogs, and warm environments are risk factors. See our chart below for which dogs are at high risk for ringworm.
However, they can also get it from a contaminated environment, such as grooming equipment, brushes, bedding, and furniture – and because the spores of the ringworm fungus are quite resilient, they can live in the environment for more than a year, waiting for a host.
Dogs at the highest risk of ringworm infection
Risk group | Why they're susceptible |
Puppies/senior dogs | Immature/weak immune systems |
Immunocompromised dogs | Pups dealing with chronic illness, recent surgery, steroid use, or stress |
Long-haired breeds (Maltese, Poodles, Shih Tzus, Yorkies, etc.) | Dense coats trap moisture and hide skin lesions |
Dogs in overcrowded environments | Ringworm spreads quickly in shelters, boarding facilities, and daycares |
Dogs exposed to infected pets | Fungal spores can spread easily in homes with multiple pets |
Dogs with allergies and skin issues | Damaged skin barrier increases vulnerability |
Treating ringworm in dogs
Seek veterinary diagnosis for ringworm
If you suspect your dog might have ringworm, your first step should always be to visit a veterinarian for a definitive diagnosis. A Wood’s lamp is used to find M canis-infected hairs. Positive hairs often glow/ fluoresce as a green color. These hairs are then collected for direct examination via plucking or scraping of material onto a drop of mineral oil.
A test like a fungal culture or PCR may be recommended to confirm diagnosis. Fluorescence is less common as animals recover and absence of fluorescence does not mean that the pet is not infected with ringworm.
Available treatments for ringworm in dogs
Treatment can be topical, systemic, or a combination of both. Topical treatments involve medicated shampoos, wipes, and creams applied directly to the affected areas.
Systemic treatments, on the other hand, involve antifungal medications given orally. The type and duration of treatment will depend on the severity of the infection.
How to know if the treatment is working
If the ringworm treatment is working for your dog, you’ll notice:
Shrinking lesions
Regrowth of hair where bald spots were
Reduced scaling or inflammation
Negative fungal cultures or PCR tests
Make sure to check in with your vet to determine if your dog is fully cured and no longer contagious.
Can ringworm recur?
Ringworm does have the possibility to recur if:
Treatment is stopped prematurely
Another infected animal is present
Your dog has underlying immune or skin issues
If symptoms return, see your nearest emergency veterinarian right away to determine the next steps of treatment.
Preventing spread of ringworm in dogs
Ringworm is contagious and can spread between pets — and even to people — so taking a few simple precautions at home can make a big difference. While your dog is undergoing treatment, it’s crucial to minimize the risk of the infection spreading.
How to protect your dog from ringworm
Keep your dog separated from other pets during treatment.
Clean and disinfect your home regularly (floors, bedding, grooming tools).
Don’t share brushes, blankets, toys, or beds between pets.
Wash your hands after handling your dog or their belongings.
Check your dog’s skin often—early detection stops the spread.
When bringing home a new pet, have them examined by a vet first.
How to protect your family from ringworm
Limit close contact between infected pets and people—especially kids, seniors, and immunocompromised individuals.
Wash hands thoroughly after touching your dog.
Disinfect surfaces your dog has touched to kill lingering spores.
Keep shared spaces (like couches and bedding) off-limits until treatment is complete.
With the right combination of veterinary treatment, environmental cleaning, and early detection, ringworm can be effectively managed and prevented from spreading and returning.
Contact VEG ER for Pets if your dog has ringworm
At VEG, we’re dedicated to ensuring that pet owners are well-informed about potential health issues like ringworm. If you notice any symptoms or have concerns about your dog’s health, don’t hesitate to get in touch. We’re open 24/7, even on holidays. Call us or walk in: no appointments taken.
