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Understanding Fungus in Dogs and How To Help

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Do some quick online research and you'll learn about all sorts of parasitic worms that can harm your dog. Heartworms, hookworms, roundworms, whipworms, tapeworms ... the list goes on. But one “worm" you may discover is not a worm at all: ringworm.

The term "ringworm" refers to a collection of pathogenic fungi, known in the scientific community as dermatophyte that can infect almost all species of animals and humans. That's one reason why it  is a serious matter in dogs — while it's not life-threatening, it can be spread to other pets or even humans in the home. 

Let's take a closer look at the cause of fungus in dogs, the symptoms it creates, and how to help your pet so everyone in your family stays safe.

What Causes Fungus in Dogs?

Dog ringworm: a happy miniature poodle

There are three members of the dermatophyte family that cause dog fungus: Microsporum canis (the most common culprit), Microsporum gypseum, and Trichophyton mentagrophytes

When these fungi infect a human, they cause a round, raised, red "ring" shape on the skin. However, the red ring may not be as apparent in our canine friends. 

The fungus feeds on the outermost layer of your dog's skin and the hair follicles, and sometimes on the nails. The infection remains superficial — it stays on the skin and will not invade your dog's body, but it can cause further health problems if it's not dealt with in a timely manner. 

What Are the Symptoms of Dog Fungus? 

While  easy to spot in humans thanks to the raised red ring shape that the fungus causes, such an obvious marker might not appear in your canine companion.

In dogs, the first sign is usually one or more circular areas of hair loss. As these circles get bigger, the skin in the center often starts to heal and grow hair again, creating the appearance of patches of hair loss. 

The hair around these skin lesions will usually be quite dry and brittle, breaking off of your dog's body easily and increasing the likelihood that the fungus will spread to other pets or humans as they come in contact with that hair.

The major symptoms of fungus in dogs include:

  • Hair loss), particularly in circular ring shapes
  • Dry and brittle hair
  • Inflamed skin 
  • Scabs or crusting on the skin
  • Brittle or broken claws (if the fungus has infected the claws)

Note that fungus usually does not cause itchiness, so you probably won't see your dog scratching at his or her ringworm lesions. This can help to differentiate fungus from other skin conditions that cause hair loss, such as mite-related skin issues or allergies.

Are Other Pets and Humans at Risk? 

Yes, a fungus can easily transmit to other pets in the home, including cats and small mammals. It can also be contracted by humans. 

The shedding or breaking of infected hairs is the main method through which fungus spreads. In fact, that's how dogs tend to get the fungus in the first place — they come into direct contact with another dog, or that dog's bedding, bowl, furniture, comb, or other object. 

To make matters worse, objects and surfaces can remain contaminated with the fungal spores for a long time — up to 20 months

It's also worth noting that some dogs can have a fungus living on their skin and in the hair follicles without showing any symptoms. These dogs, called asymptomatic carriers, can spread fungus to other animals or humans without showing any signs whatsoever.

Fortunately, most healthy adult humans are resistant to the fungus. It's more likely to affect individuals with compromised immune systems, elderly people, or young children. That said, it's possible for any healthy adult to contract the fungus, especially if there’s a break in the skin, like a scratch or small wound. 

How Is Dog Fungus Treated?

Dog ringworm: a large dog stands with his front legs up on a picnic table

A veterinarian will diagnose a case of dog fungus with a physical examination to look for clinical signs, as well as a series of tests including a fungal culture of skin or hair cells. 

Your vet may also examine your dog's hairs under a special ultraviolet light called a Wood's lamp. This tool can help the doctor detect problems, although it isn't always conclusive. 

Helping Your Dog

Most cases of dog fungus are handled using a combination of topical treatments and systemic therapy. Topical treatments involve things like medicated shampoos, which you'll use to bathe your dog regularly, as well as creams and ointments that are applied to affected areas. 

Systemic therapy means, in this case, giving your dog an oral medication with anti-fungal properties. A number of different options exist so it’s important to consult your veterinarian to see which may be a good option for your pup. .

Treating Your Environment

Since fungus is contagious to other pets and humans, taking steps to decontaminate your home environment

t is essential to stop the spread of infection. Your vet will probably recommend steps like:

  • Keeping your dog quarantined in a specific area of the house that is easy to keep clean
  • Restricting other pets or human family members from coming into contact with your pup
  • Vacuuming floors and carpets regularly
  • Cleaning potentially contaminated objects or surfaces with a diluted bleach solution 

When you handle your dog directly, perhaps to take him or her to the vet's office for another fungal culture, make sure to wear gloves. Wash your hands thoroughly after your dog is back in their designated containment area. 

When steps like these are taken and proper treatment is given for a long enough time period, the vast majority of dogs will recover fully from fungal issues. The biggest danger isn't necessarily to the health of your pooch, it's the potential for the fungal infection to spread to other family members or pets in the home. 

Can You Avoid Dog Fungus?

However, you can minimize the likelihood that your dog will get fungal issues by keeping your home clean at all times and preventing your dog from going near other infected animals whenever possible. 

It’s also a good idea to boost your dog's immune health, which is their first line of defense against disease and infection. Try natural, immune-supporting  supplements in tandem with a healthy diet. You might also consider beneficial supplements for skin and coat health. 

Generally speaking, fungus prevention isn't something you have to spend a lot of time focusing on unless your dog or other pets already had it. In that case, you'll want to make sure that it is completely cleared up before lifting your pet’s quarantine. You’ll also want to decontaminate your home and your pet's items thoroughly to ensure the fungal spores don't spread. 

To learn more about how to improve your dog’s overall health, visit the Pet Honesty blog for the latest information.