Ringworm in Dogs & Cats: Signs, Treatment, & More [Vet-Approved]

Have you observed lesions, crusty skin, round patches of hair loss, or brittle nails on your four-legged companion? These are common signs of ringworm. Ringworm in cats and dogs is a common, contagious skin condition.

Pet parents are advised to take prompt action if they suspect ringworm in dogs or cats as this infection can spread to other pets and has the potential to spread to humans as well.    

This complete guide covers everything you need to know about spotting and treating ringworm in pets, along with a few helpful prevention tips. 

What’s in this Guide? 

What is Ringworm?

Ringworm in dogs and cats is a fungal infection that affects the nails and skin. Though dogs and cats of all ages can get ringworm, this skin condition is more commonly observed in puppies, kittens, hunting animals, and pets living in warm climates.  

Cause of Ringworm in Pets

Ringworm in dogs and cats is also known as ‘dermatophytosis’ because it is caused by a group of fungi called dermatophytes’. This type of fungi requires keratin to grow. Hence, dermatophytes infect keratin-rich parts of the body, such as the skin and nails of dogs and cats.

The species of ringworm that is commonly responsible for cat or dog ringworm is called ‘Microsporum canis’ or ‘M. canis’.Both dogs and cats are natural hosts for this species of fungi. However, M. canis can also infect human skin, causing skin lesions. This means that ringworm in cats and dogs is considered to be a zoonotic disease (i.e. can be transmitted to humans).

Ringworm can be contracted by pets and humans via: 

  • Direct skin-to-skin contact with an infected dog or cat;
  • Direct contact with contaminated soil; and
  • Direct contact with contaminated items (e.g. beds, rugs, brushes).
Note: Microsporum canis, the usual species of fungi that causes ringworm in dogs and cats, also produces fungal spores, which are biological particles that contribute to spreading the fungi. M. canis’ fungal spores can be viable for as long as 18 months.

Symptoms of Ringworm in Dogs & Cats

The most common signs of ringworm in cats and dogs include the following: 

  • Fur loss or broken strands of fur in certain areas
  • Circular areas of raised, red, crusty, or scabbed skin 
  • Rough, brittle, or broken claws
Note: Some cases of cat or dog ringworm do not show obvious signs. This is when lesions are not as apparent or when a pet is simply a carrier of fungal spores. In addition, early stages of ringworm in cats and dogs might not show symptoms.

Diagnosing Ringworm in Pets

Diagnosing ringworm in pets is the first step toward treatment. A prompt diagnosis and treatment for ringworm are recommended as this type of skin disease is contagious and could, over time, leave long-living, infectious fungal spores all over the home. As mentioned earlier, ringworm in cats and dogs is also zoonotic, meaning it has the potential to infect humans: another reason why prompt treatment is advised.  

The first thing a veterinarian will do in cases of suspected ringworm is to examine the pet’s skin. Some veterinarians may use a Wood’s lamp, which emits a special wave of ultraviolet light that makes a majority of Microsporum infections glow or fluoresce. 

Depending on the case, veterinarians may recommend additional laboratory tests including fungal culture and PCR testing. Both of these tests help confirm what type of fungi is infecting a pet’s skin. 

Note: Licensed veterinarians are the only ones that can conclusively diagnose ringworm in pets. To the untrained eye, symptoms alone can lead to ringworm in dogs and cats being mistaken for allergies and bacterial skin infections. 
A photo of an agar plate, representing fungal culture, which is one of the ways to diagnose ringworm in dogs and ringworm in cats

How to Treat Ringworm in Dogs & Cats

Essentially, two types of medications are used to treat ringworm in dogs and cats: oral and topical medications. Some veterinarians may also recommend lime sulfur dips done twice a week. 

At-home treatment can last for 2 - 4 weeks. In severe cases, treatments can run for more than a month. Consistency is the key to making sure that the treatment plan is as effective as possible. In addition, regular disinfection during the course of treatment ensures that fungal spores are dealt with. 

1. Oral Antifungal Medication

In most cases of ringworm in cats and dogs, veterinarians will prescribe antifungal oral medications. These medications are considered the foundation of ringworm treatment in many cases because they disable fungi from reproducing. This sets the stage for a topical treatment to take over what’s left of the fungal infection (and fungal spores) on the pet’s skin. 

2. Topical Antifungal Medication

Topical medications for ringworm in cats and dogs include antifungal shampoos, ointments, and creams. Medicated shampoos are helpful for covering large areas of skin that are (or could be) infected by ringworm. Meanwhile, ointments and creams are more targeted towards areas showing evident ringworm infection. 

Note: When prescribed by the veterinarian, make sure to use an antifungal ointment that is formulated for dogs and cats. Ointments formulated for people are generally not as safe — because they weren’t formulated to factor in that dogs and cats may accidentally lick the medicated area:

3. Lime Sulfur Dip

Depending on a pet’s individual needs, the veterinarian may recommend lime sulfur dips in addition to topical and oral medications. Lime sulfur dips involve the use of a poured solution that targets ringworm as well as other skin parasites. Lime sulfur dips are typically done twice a week, either at the clinic or at home. 

How to Prevent Ringworm in Cats & Dogs:

Whether you’re looking to prevent infection, reinfection, or the spread of ringworm, the following are helpful tips for preventing ringworm in cats and dogs:  

1. Cleanse the Home

Microsporum’ is the group of fungi that commonly infects dogs and cats. Along with nearly all species of fungi, Microsporum produce fungal spores that can cling to bedding, blankets, brushes, and surfaces. These fungal spores are infectious for a long time. As an example, Microsporum canis’ fungal spores are viable for 18 months. 

Therefore, cleansing home surfaces and items (especially ones that have recently come into contact with an infected pet) is an effective preventive measure against dog and cat ringworm. 

Note: Not all detergents and disinfectants can kill fungal spores. Your veterinarian will be able to give recommendations on effective fungicidal disinfectants that are available in stores near you. 

2. Regularly Wash Blankets, Toys, & Brushes

Regularly washing items that your dog or cat uses is another way to prevent dog or cat ringworm. Every now and then, consider using fungicidal disinfectants when washing these items. This practice will help remove potential sources of infection.

3. Get any Skin Condition Checked by a Vet Immediately

One of the best ways to prevent dog or cat ringworm is to address skin conditions in pets promptly. This is for two reasons: (1) the skin condition may be ringworm, whether apparent, in early stages, or asymptomatic, and (2) even if the skin condition is not ringworm, it might lead to ringworm. 

Addressing a case of ringworm early will help reduce the number of fungal spores that an infected pet sheds on home surfaces.

Note: Even while pets are not yet exhibiting obvious symptoms of ringworm, they may already be shedding infectious fungal spores. Dr. Chris Lenahen, Sploot’s Associate Veterinarian explains, “Skin lesions [that are associated with ringworm] usually appear within 1–3 weeks after exposure. [...] Patients can be infected and capable of shedding fungal spores before this symptom appears.”

In addition, even if a pet’s skin condition is not ringworm per se, getting any skin issue treated will help maintain a healthy, intact skin barrier — which helps keep cats and dogs free of ringworms.

 A dog sitting in the waiting room of Sploot Veterinary Care with one of Sploot’s vet techs to get skin checked for ringworm and other skin conditions

Can I Touch My Dog or Cat if They Have Ringworm?

When handling a pet that has ringworm, we advise pet parents to wear disposable gloves. Though ringworm in dogs and cats will not always readily infect unbroken human skin, breaks in the skin (e.g. wound, scratch, eczema) will increase the likelihood of infection.

Do I Need to Separate My Dog or Cat with Ringworm From Other Pets?

It is advisable to separate a dog or cat that has been diagnosed with ringworm because this skin condition is contagious. It is also recommended that pet parents check other pets for symptoms of ringworm. 

Is Cat & Dog Ringworm More Prevalent During Certain Seasons?

Fungi thrive when the weather is hot and humid. Because dog and cat ringworm is caused by fungi, ringworm tends to be more prevalent during warmer seasons (i.e. during summer). 

Final Thoughts on Ringworm in Pets

We hope you found this guide on cat and dog ringworm helpful! If you have specific questions about ringworm in cats and dogs, consult your local veterinarian. As for pet parents in Denver, Sploot Veterinary Care is here to help! Our experienced veterinarians will be able to diagnose and treat ringworm in dogs and cats. 

Schedule a visit or come on in for a same-day appointment in our convenient locations. We also accept walk-ins. Our clinic doors are open from 10 am to 10 pm, 365 days a year. Till next time, we’re with you every pounce of the way!

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