Adventures with Rottweilers

Humungous Fungus #Rottweilers

OR the Myth about the Ringworm: It’s NOT a Worm.

As per usual, Caitlin has come up with something new for me to write about.

I dose my rotties with Milbemax so they won’t get Spiro like Jazz did, and are protected against all worms. Turns out having “worm” in the name doesn’t make it so. Ringworms are caused by a fungus.

What Is Ringworm?

Despite the name and common delusion that ringworm is caused by a worm, this highly contagious fungal infection is not connected to parasites like roundworm, hookworm or tapeworm. (So deworming is absolutely useless for this particular “worm”.)

Dermatophytosis (AKA ringworm) is usually caused by these three fungal agents: Microsporum canis, Trichophyton mentagrophytes, and Microsporum gypseum.

The fungus starts growing in the hair follicles and then spreads to the skin, causing hair loss and lesions. It occasionally infects the nails. The infection is superficial, staying in the outermost layer of skin, and only affects a few areas of the dog’s body. Ringworm has no favourites and loves all species of dogs, though young dogs, ill dogs, dogs with suppressed immunes systems, and those living in high-stress situations (crowded kennels) are more susceptible. A flea infestation also increases a dog’s susceptibility to ringworm.

Note: this is a zoonotic fungus that can spread back and forth from dogs to humans (usually through skin-to-skin contact).

Causes of Ringworm

Ringworm in dogs spread through direct contact with the fungus (infected animals, contaminated bedding/carpets/couches/brushes/etc.). The ringworm fungus also resides in soil, so a dog that loves to dig encounters it regularly. (See above for susceptibility factors.)

Fungal spores that cause ringworm can lay dormant on a variety of surfaces (as listed above) for many months. It can also be spread through the shedding of infected hairs.

Symptoms of Ringworm in Dogs

In mild cases, you might notice nothing at all. But as it progresses, the following symptoms appear:

  • Dandruff-like scaling
  • Red lesions
  • Scaling, crusting, thickening and reddening of the skin
  • Circular patches of hair loss
  • Dry, brittle hair
  • Broken hairs and poor coat
  • Darkened skin
  • Rough, brittle claws

Usually, ringworm lesions appear as roughly circular patches of hair loss. As the lesions enlarge, the central area heals and hair regrows: it looks like a worm! These lesions can be itchy, can get inflamed and develop a scabby covering.

Your dog may or may not be itchy.

There are asymptomatic carriers: dogs infected by the disease but not affected by it. They can infect others.

Note: hair loss, inflamed skin, skin problems, and changes in coat appearance can also be signs of other conditions like Cushing’s disease, hypothyroidism, nutrient imbalance, allergies, infection, parasites, etc.


Your vet will do the following to diagnose ringworm:

  • Observation. A physical exam of the dog, looking at the lesions and scaling (and searching for other underlying reasons if your dog is itchy).
  • Microscopic evaluation. Minimally invasive, this is usually the next step. Scrapings of skin and hairs from the affected areas are looked at beneath the microscope. This will rule out other skin infections (like mites) and fungal spores can sometimes be seen attached to the hair shafts. Wood’s Lamp (an ultraviolet lamp) is also used to make the secretions of the fungus stand out on the hair shaft (not 100% accurate, though).
  • Fungal culture. If still inconclusive, hair and skin samples will be sent to a lab for a fungal culture. It can take up to 4 weeks for a conclusive diagnosis, but early signs of infection can be detected in a few days.
  • Diagnostic tests. CBC, urinalysis, biochemical profile, thyroid function and other tests might also be performed to completely rule out other causes of hair loss and skin lesions – and to evaluate your dog’s overall health status.


Ringworm treatment varies with the severity of the infection.

Topical Treatment

Mild cases can be treated by antifungal creams and ointments that are directly applied to the affected areas of your dog’s skin. An antifungal shampoo, used twice weekly, is also a good way to clear your dog’s body of the fungus. In some cases, the dog’s hair will be clipped for easier access to the lesions. And sometimes your vet will recommend an entire body clipping to decrease environmental contamination.

Topical treatment will usually be necessary for a period of several weeks (even months).

Systemic Treatment

Severe cases will include topical treatment and oral medications to help your dog recover. Systemic treatment lasts a minimum of 6 weeks. Antifungal drugs may be administered daily or every other day to promote recovery.

There are adverse effects like diarrhoea, anorexia, nausea, etc. But don’t stop the treatment until your vet says so, or the infection will recur.

Environmental Decontamination

As discussed, dermatophytosis is an extremely contagious disease. Hairs of the infected dog will fall off and contaminate the environment. Part one of environmental treatment is to thoroughly clean your house, ridding it from all contaminates.

The easiest way to not clean the entire house every day: keep your dog quarantined to a part of the house that is easily cleaned (place with tiles, etc.) and wash everything with an effective disinfectant like a dilute bleach solution.

The fungal spores that live inside the hair follicles of infected dogs remain contagious for months at a time, surviving on grooming tools, bedding, furniture and clothing. Cleaning up all this hair is part of the treatment and a bit of a challenge, hence the quarantine. Daily cleaning (including mopping up with the disinfectant) will help prevent ringworm from spreading.

Remember to wash all bedding and toys with a bleach solution. (Or dispose of them and replace them.)

Disinfecting the entire environment should be repeated regularly, at least once a month, until all infected animals are infection-free.


Infected dogs remain contagious for about 3 weeks with aggressive treatment. The vast majority of dogs, if treated, will recover from a ringworm infection. Symptoms may recur if the treatment is discontinued or not aggressive enough or if the dog has an underlying condition that wasn’t treated (e.g. malnutrition). Sometimes it will recur because the dog is a carrier of dermatophytosis.

The ringworm fungus can remain infective for up to 18 months in the environment and re-infection may occur.

You can’t restrict your dog from romping in the woods or rolling on the ground – and you shouldn’t. But your dog’s favourite haunts are most likely infested with ringworm fungus. Most pet-parents don’t have to worry about ringworm prevention on a regular basis unless they have had a case of ringworm among their pets. The best way to prevent infection is to keep everything clean. Impeccable hygiene is your friend!

Further Reading:

Caitlin’s Story

Caitlin presented with dry, itchy skin and dandruff. Normal for the change of seasons (winter to spring) and the dry grass she insists on playing in. She loves playing outside, digging holes and rolling on everything.

Tea Tree shampoo barely brought relief. Special dip worked for less than 8 hours. Daily grooming and baths brought only momentary distraction.

Then I found two wounds. I thought they were bite marks – she does play rough with Cal and this wouldn’t be the first bumps and bruises resulting from him snapping.

But after doing some research, I realised that it might be ringworm. So she’s getting daily baths and supiroban ointment (just like bactroban, but actually currently available) on her wounds. Thus far it looks like it’s working. I’m not going to put her through all the emotional trauma of getting tested for something she might not even have. (Don’t worry, if she doesn’t look better by the end of the month, she’s going to visit her favourite vet.)

If your dog isn’t the type to chew up gloves, I suggest you wear a pair when handling the shampoo – it’s kind of tingling on the skin even after washing your hands thoroughly afterwards. Unfortunately, Caitlin believes that gloves (and socks!) should be treated with no mercy.

Note: I also bathe Callum to make sure that there are no spores left on him. I’ve decided to treat him like he’s part of the environmental decontamination! Thankfully it’s almost summer and this spring is already unnecessarily hot. And now I can clean the house every day without looking like a lunatic!

What are your thoughts about ringworm? Any products you believe are the best for eradicating the fungus spores? Any questions?

Want to keep up with Ronel’s Rottweilers? Follow us on InstagramPinterest and Twitter — we love to take mum’s phone and make appearances there. You can also sign up for Ronel’s author newsletter –and receive a free ebook — where Caitlin and Callum share news, too. (I won’t share your information and I’ll only email you once a month with updates on new releases, special offers, and a bit of news.)

**Legal waiver: I’m not a veterinarian, just an overprotective Rottweiler mum and pack leader. It’s always best to contact your vet if something in your dog’s behaviour is out of character.

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