What Causes Ringworm in Cats?

what causes ringworm in cats_canna-pet

What is Ringworm Infection?

Despite what its name might have you believe, ringworm doesn’t involve a worm. It’s a very common fungal infection that affects the skin, hair, and nails. Medically referred to as dermatophytosis, it also happens to be one of the most common skin disorders found in cats.

If you suspect your cat has ringworm, approach with caution because it’s highly contagious and animals with ringworm are capable of transmitting from animal to human. It’s possible for a cat to carry ringworm spores and not show any symptoms, but most of the time the signs will manifest the same.

Symptoms of Ringworm in Cats

Following initial contact, it takes approximately one to two weeks before lesions and other symptoms of ringworm begin to show up in cats. The following symptoms are typically found on your cat’s chin, head, ears, and forelimbs:

  • Circular lesions with scaly centers
  • Redness
  • Lesions with pustules
  • Generally irritated skin
  • Missing patches of hair
  • Flakey bald spots with red centers
  • Malformed nails – rough, pitted, scaly
  • Dandruff
  • Mild to severe shedding and hair loss
  • If the entire body is infected it may cause scaly and greasy skin

Some cats, mostly long-haired breeds, are known for being asymptomatic carriers. Meaning that despite carrying harmful spores, they don’t show any symptoms typical of a cat with ringworm. The tricky part is, asymptomatic carriers are still contagious — they can transmit the bacteria to other animals and even infect humans.

what causes cat ringworm_canna-pet

Ringworm presents very similarly to staph infections, and in some cases, it appears as a generic skin rash, rather than circular lesions. Therefore, it’s important to make sure you work with your vet to reach a definitive diagnosis. The three diagnostic tests that are commonly used to diagnose ringworm are: 

  1. Wood’s Lamp Examination: This lamp emits ultraviolet light that causes the infected hairs to turn a fluorescent green color. However, this method cannot detect every single case of ringworm infection, and should always be accompanied by an additional method.
  2. Microscopic examination of infected hairs: Skin scrapings and infected hairs can be collected and then examined under a microscope to detect fungal spores
  3. Culture: Taking a sample skin culture of your cat is the most reliable and effective way to identify ringworm infections. However, the downside to this method is that it is also the most timely, and can take a few weeks to receive the results, which can be worrisome if you believe your cat has been exposed to ringworm

Causes of Ringworm in Cats

Ringworm in cats is caused by directly contacting fungal spores on a source contaminated with ringworm such as other animals with ringworm, household surfaces and objects, or even humans. A cat can get ringworm by touching an infected animal or indirectly by touching materials like bedding and carpet that have contaminated skin cells. These spores feed off of skin, hair and nail proteins, which allow each organism to rapidly grow and multiply.

Unlike some bacteria, ringworm is a very resilient fungus that doesn’t necessarily need a warm, moist environment to thrive for long periods of time. It can survive in common places like bedding, furniture, dishes, carpet, or hair brushes for up to 18 months.

Ringworm is a zoonotic disorder, meaning it can be transferred from animal to animal and animal to human, and vice versa. Small children are especially at risk due to their underdeveloped immune systems and exploratory nature. Healthy adult humans are usually only susceptible to infection from an animal if they have a pre-existing skin lesion or cut.

While most healthy adult cats have built an immunity to ringworm, younger and older cats have weak immune systems that cannot easily defend against infection. Your cat may also be more prone to getting ringworm if he suffers from anxiety, malnutrition, or if he has other diseases, parasites, or viruses. Genetically, Persian and Himalayan breeds are known for being the most prone to ringworm.

Catteries and animal shelters are breeding grounds for harmful bacteria, which can quickly result in the spread of ringworm from cat to cat. Be cautious when bringing home an animal from a cattery or animal shelter — if the environmental conditions are questionable, you may want to quarantine your cat for a week or two before introducing them to the entire household.

Treating Ringworm in Cats

causes of ringworm in cats_canna-pet

Your vet will typically prescribe a topical ointment or shampoo to treat ringworm in cats that will kill the offending fungus. In some cases, oral medication may be required. Due to ringworm’s resilience, your treatment plan may last for several months.

The vet may also recommend that your cat wear a wide cone to prevent him from licking the medication and scratching lesions. During the recovery period, it’s very important to maintain a clean environment for your cat to prevent a recurrence.

Preventing Ringworm in Felines

Some cases of ringworm in cats manifest with very mild symptoms, and at times it can even be undetectable. So it’s important to frequently check your cat’s skin, and pay close attention to any behavioral changes.

Oftentimes, cats will contract ringworm from other animals or cats. Therefore, it is important to always be health conscious when bringing other animals into your home.

Preventing a Contaminated Environment

Maintaining a clean, disinfected sanitary environment is the most effective way to keep your kitty and your household, ringworm free. Ringworm spores are very light — they can live in hair and dust. When cleaning, try to avoid methods like sweeping and dusting, which ultimately just send the spores airborne.

It is recommended you vacuum or try damp mopping with a wet sweeper (such as a Swiffer) to clean your home. In addition, steam clean your carpets, replace air duct filters, paint over rusted materials, and make sure all textiles and surfaces are sanitized regularly.



  1. “Cat Skin-Problem Pictures: Lice, Fleas, Ringworms, Ear Mites, and More.” WebMD, Accessed 12 Aug. 2017. www.pets.webmd.com/cats/ss/slideshow-skin-problems-in-cats.
  2. “Ringworm in Cats.” VCA Hospitals, Accessed 12 Aug. 2017. www.vcahospitals.com/know-your-pet/ringworm-in-cats.
  3. “Ringworm in Cats.” PetMD, Accessed 12 Aug. 2017. www.petmd.com/cat/conditions/skin/c_ct_dermatophytosis.
  4. Pena, Melvin. “What Is Ringworm and What Are Its Symptoms in Cats?” Catster, 5 June 2015, Accessed 12 Aug. 2017. www.catster.com/lifestyle/cat-heatlh-ringworm-in-cats-microsporum-canis-symptoms-treatment-tips.
  5. “Ringworm in Cats – Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost.” WagWalking, 18 Oct. 2016, Accessed 12 Aug. 2017. www.wagwalking.com/cat/condition/ringworm.
  6. “Ringworm in Cats.” International Cat Care, Accessed 12 Apr. 2019. https://icatcare.org/advice/cat-health/dermatophytosis-ringworm-cats


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