Ringworm in Dogs

Puppies, animals living in stressful environments, and those with immunosuppressive diseases are most susceptible to dermatophytosis. Lesions from ringworm usually become apparent 7 to 14 days after exposure to the fungus. Infections spread through contact with an infected animal, or after exposure to a contaminated item, such as a dog collar, grooming tools, or bedding. If you in any way suspect that your dog has been exposed to ringworm or is showing signs of the fungal infection, consult a qualified veterinarian for advice. Ringworm is contagious, meaning your furry family member could possibly transmit the fungus to human members of the household.

Some dogs may be asymptomatic, which can present a problem as the ringworm can easily spread in environments where many animals congregate (like boarding kennels). If your dog is having skin related issues, see the veterinarian promptly. If dermatophytosis is the case, early eradication will make the contamination of others less widespread throughout your human and animal companion brood.

• The skin may or may not itch
• There may be the appearance of dandruff like flakes
• The skin could be red
• There may be broken hairs on the coat
• The hair may fall out
• The ring could have inflammation within it
• Hair may begin to regrow within the circular, crusty patch
• There may be a presence of raised, rounded, nodular lesions (granulomatous)
• The claws could be brittle and broken

Types

There are many types of fungi that can cause ringworm. The most common types in the canine world are listed here. These three types are zoonotic, meaning they can be spread between animals and humans.

• Microsporum canis
• The main reservoir for this fungus is cats and dogs
• It feeds on the keratin of the outer layers of skin, hair, and nails
• Microsporum gypseum
• It is found in soil
• Most common in South America
• Trichophyton mentagrophytes
• In humans, it is known as athlete’s foot
• It is found in moist areas
• It manifests as ringworm in animals

The fungi that cause ringworm can remain dormant for up to 18 months. This cements the fact that diligent care must be taken if you learn that your family pet has ringworm.

• Dogs and humans with compromised immune systems are more susceptible to dermatophytosis
• Spores can be found in soil
• Fleas can transmit ringworm
• Contact with contaminated items can spread ringworm (combs, brushes, dog bowls, furniture, bedding)
• Direct contact with the fungus on an animal or person is a source of transmission

When you arrive at the clinic, the veterinarian will start the visit with an examination. Be prepared to give as much detail about the recent behaviors of your canine companion. If you know or suspect that your dog has been exposed to ringworm, alert the veterinary caregiver right away. She and her team will want to be as diligent as possible in containing the possible fungus to one area, and will do an extensive cleanup after you and your pet have gone home.

The diagnosis of dermatophytosis is typically done by the following methods.

• Identification of ringworm lesion
• This is not the most accurate way to diagnose ringworm because other diseases (like skin mites or allergic skin disease) can mimic the fungus. However, it is a good starting point, as the presence of scaly, crusty ring like lesions may be indicative of ringworm when seen in addition to other diagnostic results.
• Fluorescence of infected hairs
• Hairs belonging to your dog will be placed under a special light, called a Wood’s lamp. Ultraviolet light will show the presence of fungi excretion attached to the hair. Microsporum canis will glow a fluorescent yellow-green. It should be noted that microsporum gypseum and trichophyton mentagrophytes do not glow under the fluorescent light, so this method does not completely rule out a ringworm infection.
• Fungal culture of hair or skin cells
• This is the most accurate. Most cultures, if positive, will show as such within ten days. It is possible, though, that the results can take up to a month to identify if the spores grow slowly.

Looking at dog hair under the microscope, and taking a skin biopsy are two other methods less commonly used, due to a low rate of accuracy.

The veterinary caregiver will decide on the course of treatment for the ringworm affecting your dog. She will give you full instructions on the diligence and care that must be taken in order to eradicate the fungus from your pet, and from your home.

Topical creams and ointments may be used alone or in conjunction with a medicated shampoo, depending on the severity of the infection. The veterinarian will advise on how long a cream or ointment should be applied, but typically the application is once a day for 10 days, up to 4 or 6 weeks. Medicated shampoos are often used twice a week. The shampoo should be left on for 5 minutes before rinsing, taking care to avoid the eyes, nose and mouth.

Oral antifungal medications are generally used for a six-week minimum. A culture may be taken about 2 weeks after the medication is started, and then 2 weeks after that, and possibly one more time. Once the veterinarian has seen three negative cultures, it is conceivable that the medication can be stopped. Do not stop the treatment before the veterinary caregiver has given the okay, or your dog may have a recurrence of the fungus.

Clipping is only recommended if the infection is severe. The reason for this is that any nicks that your canine buddy may get while getting clipped can cause the fungus to spread further into the skin.

During the treatment period, it is highly advised that you keep your dog under a quarantine of sorts; do not allow contact with family members, other household pets, or any other dogs in the vicinity. In fact, a wise decision would be to have the veterinarian do a fungal culture on all pets living with you. (Infected pets remain contagious for about three weeks, even once treatment has begun.) Be sure to wash your hands thoroughly after treating your dog, or perhaps wear gloves when applying ointments and creams.

Don’t be surprised if you see areas of hair loss continue to get bigger after treatment has started. This is normal. The patches will begin to get smaller in size after two weeks, and the hair should start to grow back. If you are not seeing improvement, let the veterinarian know. She will need to do two or three cultures after treatment begins, since three negative cultures in a row is the most common indicator used for determining the resolution of the dermatophytosis.

Disinfecting and keeping clean all areas of the house will be necessary as part of managing the ringworm infection. Keep your pet in a room without carpets. Vacuum and mop the quarantine area daily at minimum. The use of bleach (at a strength of 1:10 - 1:100) is suggested, to be used over all flooring in the house and particularly in the room where your dog is being kept. Lysol can be used to further disinfect floors, radiators, windows, and vehicles your dog may have been in. Wash bedding often. As well, wash (or consider throwing out) collars and grooming aids. In reality, the entire house must be disinfected, including drapes and carpets.

If clipping of your dog is to be done in any amount, be sure to dispose of the dog hair carefully. This may all seem to be unsurmountable at this point, but with diligence, patience and the help of the veterinary team, you can have success in the elimination of the ringworm.

Ringworm can be diagnosed visually, although that is not as conclusive as a fungal culture or doing a Wood’s Lamp examination. The fungal culture is done on the hair or skin cells and costs $45 on average. Another method used to diagnose ringworm is an examination using Wood’s Lamp. The Wood’s Lamp method illuminates any fungus on the dog’s hair. If the veterinarian chooses to use this method, it can cost $20 - $50 on average. Once your dog has tested positive for ringworm, the veterinarian will begin treating it. Topical creams and ointments can cost between $20 and $100. This method can be combined with a medicated shampoo, adding an additional $10 to $35 per bottle. The last method of treatment that the veterinarian may suggest is using oral antifungal medications for about six weeks. These oral medications cost an average of $20.