Ringworm in Dogs - Symptoms, Causes, Pictures, and Treatment

Understanding Ringworm in Dogs

Ringworm is a highly contagious fungal infection that can affect dogs. Despite its name, ringworm is not caused by a worm at all. Rather, it is caused by various species of fungi in the genera Trichophyton or Microsporum. These fungi feed on keratin, a protein found in skin, hair and nails. Ringworm leads to circular, red, itchy lesions that can appear anywhere on a dog's body. Left untreated, ringworm can spread rapidly between dogs and even to humans. While ringworm in dogs is usually not serious, treatment is important to relieve discomfort, limit spread and prevent recurring infections.

Symptoms of Ringworm in Dogs

The most common symptom of ringworm in dogs is the appearance of circular bald patches. The skin in these areas will appear red and scaly. The edges of lesions usually appear most inflamed or scaly, while the centers appear to be healing. As the name suggests, lesions are often round or ring-shaped, but may also appear as irregular patches or bumps. Lesions are usually not itchy or painful. Though lesions can appear anywhere, they are most commonly seen on a dog's head, ears, forelegs, tail or paws.

Some dogs may develop a more generalized form of ringworm that leads to hair loss over larger regions of the body. Dogs with longer hair may appear to have uneven clumps of hair loss. Ringworm on the paws may lead to swelling, nail loss and lesions between toe pads. Young, sick or immune-compromised dogs are more likely to develop widespread lesions.

In some cases, dogs do not display skin lesions at all. These dogs are known as "carriers". They harbor the ringworm fungi without any outward symptoms, but can still transmit it to other animals and humans.

Causes and Transmission of Ringworm

Ringworm is caused by keratinophilic fungi in the genera Trichophyton or Microsporum that live on skin, hair and nails. Different species tend to prefer different hosts and locations on the body. For example, Microsporum canis is most often found on domestic dogs and cats and causes lesions on the head, neck and forelimbs. Other species such as Trichophyton mentagrophytes are more often found in rodents but can spread to dogs. Spores from these fungi are very hardy and can survive for long periods in soil or pet hair.

Dogs most often get ringworm through direct contact with an infected animal or human. The fungi are easily spread by contact with fur or skin lesions and live spores can be spread through localized contact or airborne transmission. Ringworm spores can also live on combs, brushes, bedding and other environmental surfaces. Dogs in high traffic areas like shelters or breeders are at highest risk of infection.

While ringworm is contagious to other animals and humans, dogs themselves do not spread the infection evenly over their own body. This is why lesions usually appear as localized patches rather than all over the body.

Certain dogs are at increased risk of contracting ringworm or having more severe symptoms:

• Puppies - their immune systems are not fully developed
• Dogs with suppressed immune systems
• Dogs in shelters or crowded living conditions
• Long-haired dogs - spores have more hair to adhere to
• Dogs with existing skin issues like allergies or trauma

Diagnosing Ringworm in Dogs

Ringworm can be tricky to diagnose as symptoms may be nonspecific. The appearance of circular hair loss is strongly suggestive of ringworm, but other conditions like fungal or bacterial infections, allergies, endocrine disorders or parasite infestation can also lead to similar hair loss patterns.

To definitively diagnose ringworm, your veterinarian will:

• Perform a clinical examination of the dog's skin
• Use a Wood's lamp to check for ringworm fungi that glow under blacklight
• Take samples of hair and skin scrapings from lesions
• Culture the samples to grow and identify any fungal organisms

Skin scrapings or hair samples may be examined under the microscope to look for characteristic fungal spores. Fungal cultures can take up to 2-4 weeks to grow in the lab and confirm ringworm.

In straightforward cases, your veterinarian may go ahead and prescribe topical antifungal medications before culture results return. This provides early treatment while awaiting confirmation.

Treatment for Ringworm in Dogs

The primary treatment for ringworm in dogs is antifungal medications. Antifungals are available as oral medications, topical ointments, dips and shampoos. Treatment typically lasts from 2-8 weeks depending on severity.

Oral antifungals like itraconazole or terbinafine are usually more effective than topicals alone. However, topical antifungals like miconazole, clotrimazole or lime sulfur dips provide important localized treatment to speed healing of lesions.

For more severe or generalized infections, combination therapy with systemic oral and topical antifungals may be prescribed. All household animals in contact with the infected dog should be checked and treated as well.

In addition to medical treatment, your veterinarian will likely recommend:

• Clipping hair around lesions to reduce fungal load
• Disinfecting grooming supplies and household surfaces
• Washing bedding regularly in hot water and bleach

Isolating the infected dog can help prevent spread to other pets. Be sure to wear gloves when applying topical treatments. Wash hands and avoid contact with lesions to prevent human infection.

While most dogs respond well to treatment within a few weeks, some dogs may take longer. Seek prompt veterinary care if lesions worsen or persist beyond expectations. Recurring or chronic ringworm can be frustrating to treat.

Preventing Ringworm in Dogs

Ringworm prevention focuses on the following areas:

• Environmental management - Promptly isolate infected dogs. Disinfect grooming supplies, bedding areas and household surfaces. Avoid sharing grooming supplies between pets.
• Strengthening immunity - Make sure dogs are up-to-date on vaccines. Feed a high-quality diet. Avoid immunosuppressive medications when possible.
• Limiting exposure - Avoid contact with stray or untested animals. Limit visits to dog parks, shelters and groomers during outbreaks.
• Fungal culture screening - Consider periodic fungal cultures of asymptomatic high-risk dogs like shelter dogs or pets in frequent contact with potential carriers.
• Topical therapy - Apply antifungal shampoos or rinses periodically to long-haired dogs in endemic areas as a preventive measure.

While ringworm can be frustrating and concerning, prompt treatment, decontamination and prevention practices are usually effective in controlling spread. Be sure to work with your veterinarian to safeguard the health of your canine companions.

What Does Ringworm Look Like in Dogs?

Ringworm causes red, itchy, circular lesions with a scaly border and thinning hair. Though called ringworm, these lesions may appear as:

• Round, red, bald patches
• Irregular, inflamed, crusty patches
• Red bumps with pustules and hair loss
• Generalized scaling and hair loss over larger areas
• Red, inflamed skin between the toes

Infected dogs often develop lesions first on the head, ears, forelegs, tail or feet. Paws may become swollen and crusty. Lesions are not usually itchy or painful. Long-haired dogs may develop mild clumping or patchy hair loss.

Some key characteristics help distinguish ringworm from other skin problems:

• Circular or ring-shaped lesions with central hair re-growth
• Scaly, inflamed lesion borders that spread outward
• Fluorescence under Wood's lamp examination
• Presence of fungal spores on hair microscopy
• Positive fungal culture

Accurate diagnosis requires microscopic evaluation and fungal culture from skin scrapings or hair samples taken from around the edges of lesions.

Ringworm Pictures in Dogs

Here are some pictures to help identify ringworm lesions in dogs:

Ringworm on a dog's nose - Note the round, red lesion with hair loss and scaly borders. The inflamed border spreads outward while the center appears to be healing.

Ringworm on the legs - These irregular lesions show reddened, crusty patches with hair loss on the front legs. Lesions often appear on the forelegs.

Severe facial ringworm - This dog has extensive lesions over the face, muzzle and around the eyes. The skin is scaly, red and inflamed with hair loss and crusting.

Ringworm on the abdomen - Ringworm can occur anywhere on the body. This dog has circular, red patches with hair loss spreading outward.

Ringworm between the toes - Interdigital ringworm leads to redness, swelling and crusty lesions between the toes and foot pads.

Being able to identify ringworm lesions helps detect infection early and prevent spreading to other pets and humans. While ringworm has a distinct appearance, veterinary tests are still needed to differentiate it from other problems.

Treating Ringworm in Dogs

Ringworm is highly contagious, so treatment focuses on antifungal therapy combined with environmental decontamination. Most dogs respond well and recover fully within a few weeks.

Medications

Veterinarians typically prescribe a combination of oral and topical antifungal medications to treat ringworm. Common prescription medications include:

• Oral antifungals (itraconazole, terbinafine, fluconazole) - treat infection internally
• Antifungal shampoos and dips (miconazole, chlorhexidine, lime sulfur) - disinfect skin lesions
• Antifungal ointments and creams (miconazole, clotrimazole) - provide localized treatment

Oral antifungals are usually more effective for ringworm. However, topical antifungals are critical to speed healing of existing lesions and prevent self-reinfection. Treatment is typically continued for 2-4 weeks after lesions resolve.

Supportive Care

In addition to medications, the following supportive care measures are recommended:

• Clip hair around lesions to reduce fungal load
• Use medicated shampoos weekly
• Disinfect all grooming tools, bedding, surfaces
• Isolate infected dogs from other pets
• Wear gloves when applying topicals

With aggressive medical and environmental treatment, most straightforward cases of ringworm resolve within a few weeks. However, treatment may need to be continued for 2-3 months in widespread or chronic cases.

Prevention

Preventing ringworm involves:

• Promptly treating any infected pets
• Disinfecting all exposed environments
• Avoiding contact with stray/infected animals
• Limiting exposure to shelters, groomers, parks during outbreaks
• Not sharing grooming supplies between pets
• Periodically applying antifungal shampoos to dogs at high risk

While frustrating, ringworm infections can generally be controlled with vigilance. Restrict contact with your dog until fully recovered to prevent human infection. Alert your veterinarian to any worsening of symptoms or lack of improvement.

Ringworm in Dogs - Key Takeaways

• Ringworm is a fungal skin infection, not an actual worm.
• It causes circular, scaly skin lesions that can be mistaken for other conditions.
• Diagnosis requires microscopic evaluation and fungal culture of skin samples.
• Oral and topical antifungals, along with environmental disinfection, are the basis of treatment.
• Treatment is continued for 2-4 weeks after clinical resolution of lesions.
• Prevention focuses on promptly treating infected animals and disinfecting exposed environments.
• While contagious and frustrating, ringworm is very treatable with an aggressive management approach.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.