What is Ringworm?
Image credit: Lisa Zins via Flickr
Ringworm is a fungal infection that can occur in all mammals, including cats and humans. Despite the name, there are no worms involved in the infection. The name, ringworm, actually comes from the circular patterns of the resulting skin rash.
The microscopic fungi that cause Ringworm in cats are called dermatophytes. Dermatophytes originate in the soil where their population is kept in balance by other microorganisms. When removed from their natural environment, the dermatophytes become parasites that digest keratin, the protein found in hair and nails. As they digest, they reproduce rapidly, creating millions of single-cell spores that can each become their own microorganism. Ringworm is spread through contact with infected items (such as furniture or grooming tools) or other animals (such as other cats or rodents).
There are three main types of fungus that are the cause of Ringworm in cats:
• Microsporum Canis
• Microsporum Gypseum
• Trichophyton Mentagraphytes
In 98% of cases of ringworm in cats, the fungus is found to be Microsporum Canis.
Which Cats Are Most Likely to Contract Ringworm?
Ringworm does not affect all cats equally. Cats that are most at risk are kittens (under 1 year of age), geriatric cats (aged 15 and over) , and cats with long hair. Other factors include:
- Overall Health
- Immune System Health
- Condition of exposed skin surfaces
- Grooming habits
The health of the cat’s immune system is vitally important to the spread of a Ringworm infection. Dermatophytes prefer to grow on the dead cells of the cat’s skin and hair. The infection stops when it reaches inflamed tissue (which is a reaction of an activated immune system). This means that cats that are suffering from FIV, FeLV, malnutrition, cancer, persistent stress, or that are pregnant or lactating, will have a more difficult time fighting off Ringworm.
What Are the Symptoms of Ringworm in Cats?
Image credit: Rocky Mountain Feline Rescue Via Flickr
Important Note – DO NOT try to self-diagnose Ringworm. Ringworm can not be diagnosed by looking at the symptoms with the naked eye. There are other skin conditions that can mimic these same symptoms. It is very important that your cat sees a veterinarian if you suspect that they may have Ringworm.
Once a cat has been in direct contact with an animal or surface that is affected with Ringworm, the incubation period of the Ringworm is between 4 days and 4 weeks. Many cats that have Ringworm, do NOT have symptoms, but can still spread the infection to other cats. Cats that do have symptoms may present with:
- Circular rash on the skin
- Poor coat
- Irritated reddened skin
- Darkened skin
- Hair loss/broken hair
- Raised lesions that may ooze
The most common symptom is areas circular hair loss. All symptoms are most likely to be found on the face, ear tips, tail, or feet.
How Does a Veterinarian Diagnose Ringworm in Cats?
- A Visual Assessment
Your veterinarian will look over your cat’s whole body to see the extent of the infection.
- Examination with a Wood’s Lamp.
A Wood’s Lamp is a special type of ultraviolet light. In complete darkness, they will visually examine the cat’s whole body once again watching for any areas that fluoresce in the ultraviolet light. Areas of Ringworm will fluoresce as lime green or blue and white. However, this test is not entirely reliable. It has a high rate of false negatives. Other tests must be done to confirm a Ringworm infection.
- Examination Under a Microscope
Your veterinarian will take a few suspicious hairs and examine them closely under a microscope. They will be looking for abnormalities in the hair itself (swollen, frayed, irregular or fuzzy in outline, etc) as well as looking for specific spores and fungal characteristics.
- A Fungal Culture
Your veterinarian will take swabs of potentially infected areas to grow in a culture. This test MUST be completed to diagnose Ringworm. However, results from this test can take a few weeks to come in, so the tests above will be used to determine a preliminary diagnosis. The preliminary diagnosis will help you to begin treatment as quickly as possible. Fungal cultures will need to be repeated through the process to ensure that the infection is going away.
What Are the Treatments for Ringworm in Cats?
There are no quick cures for Ringworm in cats. Ringworm infection in an otherwise healthy cat may self-resolve (no treatment) in 9 months to 1 year. With treatment, the same cat may see the resolution of the infection in 6 weeks.
Treatment will include both medications (topical, oral, and shampoos) and cleaning and sterilizing the cat’s environment. Ringworm is a zoonotic disease, and therefore, will easily transfer to other humans and animals that live with the affected cat.
Remember the 5 D’s when cleaning the environment for a cat with Ringworm:
Find out which humans and animals in your home are infected with Ringworm.
Dispose of any exposed items that can not be washed or disinfected.
Remove clutter from surfaces and remove dust. Vacuum daily and discard the vacuum bags every day. Commercially steam carpets (heat over 110 F/ 44 C is needed to kill Ringworm). Replace furnace and air filters.
Use a 1:32 solution of bleach on surfaces. Leave the solution to sit for 10 minutes before rinsing it away. Wash contaminated bedding and clothing separately from non-contaminated items.
Have people and pets, as well as the environment, re-cultured as often as recommended to be sure that the treatment has been effective.