What does fungal look like in dogs

By Isabella Storyclaire

last updated January 14, 2025

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Identifying and Treating Fungal Infections in Dogs

By Reyna Gobel

Bacteria and viruses are what typically spring to mind hen pet parents think infection, but fungi can also be to blame. While not as common as bacterial or viral infections, fungal infections can be just as serious. Dogs can contract fungal infections from other animals, from the environment, or as a result of the overgrowth of fungi that are naturally present on their own bodies. Every pet is potentially at risk for contracting a fungal infection, and an accurate diagnosis is necessary before appropriate treatment can begin. Read on to learn more about fungal infections in dogs.

Fungal Skin Infections

When your dog starts scratching himself more than is normal, it can be hard to tell whether its because of an allergy, flea bites, infection, or something else. Excessive itching can be quite worrisome, especially if your dog develops bald spots or damages his own skin as a result.

One telltale sign of fleas is the presence of flea dirt (small black clumps of flea feces) on your dogs skin and fur. If you see flea dirt or actual fleas, treat him right away. But if fleas or ticks arent to blame, dont self-diagnose or rely on Dr. Google, warns Dr. John DaJong, a veterinarian at Newton Animal Hospital in Massachusetts. After performing a complete physical exam, your veterinarian can conduct specific tests to help diagnose the problem and identify whether a fungal infection is to blame.

Lets look at two common types of fungal infections that affect the skin of dogs and how to treat them.

Ringworm

Ringworm is a common fungal infection in pets. It can affect a dogs skin, fur, and also the nails. Common symptoms include hair loss, itching, flaky or crusty skin, and misshapen or brittle nails. While you should treat any infection as soon as possible, time is of the essence with ringworm because it can easily spread to other household animals and humans, says Dr. Andrew Rosenberg, a veterinarian at Riverdale Veterinary Dermatology clinic in Riverdale, New Jersey.

To diagnose ringworm, your veterinarian will perform a fungal culture of hair or skin cells or a microscopic examination of a hair sample. Depending on the severity of the infection, ringworm may be treated with medicated baths and dips and/or oral antifungal medications. Vacuuming and disinfecting the house will also help lessen the chances that ringworm will spread between pets and people.

Yeast Infection

Overgrowth of yeast on a dogs body can lead to irritating yeast infections, commonly affecting the skin, paws, and ears. These infections can be extremely uncomfortable for dogs, says Rosenberg. Theyre generally secondary to allergies or other conditions that disrupt the skins ability to control the yeast that normally live there.

If I suspect a dog might have a yeast infection, I take an impression smear of the area that might be infected and look at it under a microscope, Rosenberg says. When the slide is stained, the yeast look like little purple peanuts.

Treatment normally involves an antiseptic or antifungal drug applied to the skin. Oral medications may be necessary in severe cases. Unlike ringworm, yeast infections arent contagious to other pets or people. To prevent yeast infections from recurring, its important to treat any underlying conditions as recommended by your veterinarian.

If your pet is constantly itching and scratching, schedule an appointment with your veterinarian. Unfortunately, not all conditions can be solved with one visit. Sometimes it could take several visits to pinpoint the cause of your dogs itching or require a visit to a veterinary dermatologist, Rosenberg says.

Systemic Fungal Infections

Fungal infections on the surface of the body are bad enough, but those that invade deeper structures can have even more serious consequences. Lets look at several common types of systemic fungal infections in dogs and how to treat them.

Blastomycosis

Blastomycosis is most commonly diagnosed in dogs that have spent time in Mississippi, Ohio, Missouri, Tennessee, the St. Lawrence River valley, the mid-Atlantic, and around the Great Lakes because the types of soil that are typically found in these areas support the growth of the fungus. Dogs that spend time sniffing around in the dirt are at risk for inhaling fungal spores, which can lead to a lung infection, says Dr. Jennifer Coates, veterinarian and author of Dictionary of Veterinary Terms, Vet-Speak Deciphered for the Non-Veterinarian. From there, the organism can travel almost anywhere in the body. According to Coates, common symptoms include poor appetite, weight loss, coughing, difficulty breathing, limping, eye problems, skin lesions (particularly around the toenails), enlarged lymph nodes, and fever. If the disease is caught early enough, treatment with an oral anti-fungal medication can be curative.

Cryptococcosis

While cats are more commonly infected with the fungus Cryptococcus, Coates says dogs tend to develop a more severe form of the disease. The fungus is present in soils world-wide but may be especially prevalent in areas where pigeons and other birds congregate. As is the case with blastomycosis, dogs typically inhale the Cryptococcus fungus, leading to a lung infection. It can then spread almost anywhere in the body, which can cause symptoms ranging from lethargy, coughing, nasal discharge, eye problems, skin lesions, and even seizures and other neurologic abnormalities. Coates warns that treating cryptococosis can be difficult. Oral antifungal medications may need to be given for a year or more and some dogs will still succumb to the disease.

Coccidioidomycosis

Dogs can get coccidioidomycosis (also known as Valley Fever) from inhaling dust or dirt that contains coccidioides fungal spores,says Dr. Carol Hillhouse, a veterinarian in Panhandle, Texas. It tends to grow in desert areas with little rain and sandy soil, such as California, Nevada, Arizona, New Mexico, and Texas, she says. Strong winds, earthquakes, construction areas, and even crop harvesting can stir up the spores into the air.

Once the spores are inhaled, the fungus may simply cause a chronic cough, Hillhouse says. In other cases, especially if immunosuppressed, the dog may develop pneumonia or the fungus can spread to other areas in the body, such as bone or the eyes, she says. It can be difficult to diagnose, and usually requires radiographs, blood, and cell testing. Valley fever requires long-term treatment with oral antifungal medications, but the prognosis is pretty good if caught early, she says.

Histoplasmosis

Another soil-borne fungus, Histoplasma, prefers the temperate climates of Ohio, Mississippi, and Missouri River Valleys, Hillhouse says. This fungus grows best in nitrogen-rich soil, such as bird and bat excrement, and is usually acquired by inhalation of the organism from the environment.Infected dogs can show weight loss, fever, cough, eye inflammation, vomiting, and diarrhea, she says. Often, a combination of blood and urine tests, as well as radiographs, are used to make the diagnosis. Sometimes biopsies are required as well. Treatment involves long-term fungal medication, but prevention is best by restricting access to soil that is contaminated with bird or bat droppings.

Aspergillosis

Infections with Aspergillusfungus are usually limited to a dogs nasal passages. Aspergillosis can affect dogs residing in almost any part of the country since the fungus is present in most soils. Treatment typically involves anesthetizing the pet and infusing his nasal passages with a liquid anti-fungal medication. Most dogs will recover if treated appropriately, although a second treatment may be necessary in some cases.

Preventing Fungal Infections in Dogs

Fungal infections in dogs range from localized annoyances to potentially fatal systemic diseases. Prevention is not always possible, but common sense measures can help. If you live in an area where a certain type of fungal infection is endemic, avoid high risk environments. Pets with ringworm should be isolated to limit the spread of the disease to people or other animals. Finally, appropriately manage any underlying health problems that increase your dogs risk for developing a fungal infection.

Fungal Infections in Dogs

Oomycosis (also called pythiosis) is a disease caused by Pythium insidiosum, which is not a true fungus but a water mold related to algae. It occurs in some tropical and subtropical areas of the world and is seen in warmer to temperate sections of the US. In dogs, pythiosis is most often encountered in Southeast Asia, eastern coastal Australia, South America, and the United States, especially along the Gulf coast. In the US, the disease most often is seen in fall and winter months.

These organisms cause disease when animals come into contact with the infecting zoospores in water, usually by ingestion. Pythiosis most often affects the gastrointestinal tract in young adult dogs, especially Labrador Retrievers. The usual site of infection is the stomach and the adjacent intestinal tissues, but any part of the gastrointestinal tract may be infected. Affected dogs often will have a history of upper gastrointestinal tract obstruction and may have an abdominal mass the veterinarian can feel during examination. Common signs include vomiting, weight loss, and loss of appetite. The weight loss can be severe, but affected dogs usually do not appear generally ill until the infection is well advanced.

Less frequently, dogs will have a pythiosis infection concentrated in the skin and adjacent tissues. A wound has usually allowed the entry of the infective zoospores into the skin tissues. Many of these animals have a history of swimming or being in swampy areas. Non-healing, tumor-like nodules may be present. They often grow rapidly. Some lesions may have a focused area of dead cells and a spongy appearance. Such lesions are usually on the legs, neck, near the place where the tail connects to the body, or on the perineum (the space between the anus and scrotum (male) or vulva (female)). They can, however, be seen anywhere on the body.

Lagenidiosis is a disease involving theskin, the area beneath the skin, and multiple parts of the body, most often the legs, mammary glands, perineum, or trunk. It has been recently reported in dogs from the southern United States. Lagenidiosis also is caused by a water mold (Lagenidium species). There are at least two species of Lagenidium that affect dogs, one of which progresses quickly. The slower developing form of lagenidiosis is very similar to the skin form of pythiosis. The faster developing form can involve multiple, organs across the body. Internal lymph nodes, the lungs, and large blood vessels (such as the aorta or vena cava) may be affected. This can lead to large bulges in the wall of the blood vessels (called aneurysms) that can rupture and cause sudden death.

Dogs exposed to warm, standing fresh water are more likely to be in contact with the infectious zoospores and may have increased risk for both pythiosis and lagenidiosis. Reports of animals being infected with no known history of being near water suggests that animals may be infected by contact with resistant spores that form in wet soil and on grass.

The diagnosis of lagenidiosis and pythiosis is made with laboratory tests including cultures and blood tests. The treatment of choice for pythiosis and lagenidiosis has been aggressive surgery to remove infected tissue, but the disease is often too extensive at the time of diagnosis to allow complete removal. Whenever possible, complete amputation of affected limbs may be curative. Your veterinarian may recommend surgery followed by treatment with antifungal drugs. Approximately 20% of dogs will respond to longterm antifungal treatment. For most infections the outlook is guarded to poor, even though there have been advances in treatment. In some dogs, a therapeutic vaccine (one given to treat a disease rather than prevent it) has helped cure the condition.

Also see professional information regarding oomycosis

What Does Ringworm Look Like on a Dog?

Just like humans, dogs can also get infected by ringworm. If youre not sure what ringworm looks like on a dog, then below I will describe the signs and include pictures. After looking at the pictures or ringworm on a dogs skin, belly, or nose, please consult with a vet for next steps.

Ringworm on a dog looks like circular-shaped bald hair patches on multiple areas of the dogs body including their belly. The patches typically have a crusty covering like dandruff. In serious cases, ringworm isnt dry-looking. Instead, it appears as red, round-shaped patches of missing hair.

Below are pictures of what ringworm looks like on a dog, then further on how dogs get an infection, the signs, whether it spreads from dogs to humans, how to treat it, and most importantly, how to prevent re-infections.

What does ringworm look like on a dog (pictures)?

All the pictures are in this video:

All dogs can get ringworm

Young, old, long-haired, or short-haired: any dog can develop ringworm. Its a common infection as its very contagious. And contrary to what many think, ringworm isnt one of the usual intestinal worms. Its a fungal skin infection.

Sure, it may look like a worm curled up underneath a dogs skin. But thats simply how ringworm got its name. Its not a worm, its a fungus.

While there are over thirty fungi species known to cause ringworm infection, only three are responsible for almost all ringworm cases in dogs: Microsporum gypseum, Microsporum canis, and Trichophyton mentragrophytes.

Researchshows that the fungus Microsporum canis is the culprit in 70% of all ringworm infection cases in dogs.

The ringworm fungus lives on the outer layer of your dogs skin. It doesnt penetrate deep inside the skin. If your dog has this infection, you will notice circular-shaped bald hair patches on multiple areas like the ears, feet, face, chest, belly, nose, and claws.

Althoughringworm in dogs looks to mostly appears on these parts, it can show up anywhere else in your dogs body.

The skin on the circular bald patches will be dry (with a brownish or grayish color) and look like its peeling off. In serious cases, ringworm may appear as red, bald hair patches with tiny pimples (in the shape of a ring) surrounding the inflamed spot.

These patches start out as the size of a pea and, if left untreated, spread out into wider circular-shaped patches.

The fungus causing the infection may determine how mild or serious the ringworm will appear. A dogs immunity (whether weak or strong) will also influence the severity of the infection.

Though not life-threatening, ringworm can be uncomfortable as it may cause itchiness.

Ringworm infection can also attack the skin under your dogs nails (or the skin bordering the nails). After some time, the nail will become discolored and too brittle.

Handy Hint: Here are the odds of you getting worms from your dog.

How do dogs get ringworm?

Dogs get ringworm at any point in their life because of how easily this infection spreads. Your dog can get it through any of the following ways:

If they have bodily contact with a person suffering from ringworm.
If they have bodily contact with a pet that already has ringworm.
If they lie on or touch any objects contaminated by the ringworm fungus. For instance, if your dog sleeps on the same bed with someone or a pet infected by ringworm.
If they get into contact with contaminated soil. The ringworm fungus ends up in the soil if an infected pet lies on the ground or simply shakes off, dropping some of the fungus-carrying fur.

While in the soil, thefunguscan remain alive for close to 18 months! A healthy dog can easily pick up the fungus and develop a ringworm infection.

Most dogs contract ringworm from the dog park. Theres a high likelihood of them getting into contact with dogs carrying the fungus or playing on contaminated soil.

Its also worth mentioning that some dogs may also have ringworm but are yet to show the obvious signs. If your dog interacts with such dogs at the park, they will get infected.

What ringworm does when on your dogs body

Like every other fungal infection, the ringworm fungus must eat to survive on your dogs body. And the problem is that as it feeds, it causes damage.

Ringworm feeds on a dogs hair strands and a certain protein compound found on the fur and skin keratin.

This protein keeps your dogs hair, skin, and nails healthy and protects against damage. As the fungus eats up keratin and the hair strands, your dogs fur will become brittle and fall, leaving round-shaped bald patches.

Feeding also gives the fungus energy to reproduce millions, if not thousands, of fungal spores on your dogs body.

Think of these spores as dust particles of the ringworm fungus. If not treated, your dog will infect you and other pets because they will leave these spores everywhere.

Pro Tip:Always wear gloves when inspecting your dogs body for ringworm. Its also best to wash your hands afterward and disinfect the gloves.

Ringworm is azoonoticinfection, meaning dog parents can contract ringworm from their dogs.

If your dog is suffering from ringworm, you shouldnt touch them. Plus, if they leave hair on your curtains, couch, carpet, kitchen counter, or clothes, you (and your guests) risk developing ringworm if you touch these objects.

What to do if you suspect your dog has ringworm infection

As much as its said that ringworm in dogs clears up on its own, waiting for it to simply vanish will only cause more harm.

For starters, its not known how long it can take for ringworm to disappear naturally.

Waiting means your dog will develop more bald patches before they start recovering, and their coat will look worse. They will also infect you and others within that waiting period.

Early treatment will help kill the fungal spores on your dogs body, so your dog will have a better chance of becoming ringworm-free sooner than later.

If youve spotted what looks like ringworm on your dog, you should see the vet. They will perform diagnosticteststo confirm whether the skin infection is indeed ringworm.

Once they make a ringworm diagnosis, they will prescribe the most effective treatment that suits your dogs case (if its a mild or severe infection). Vets often treat ringworm using the following:

Anti-fungal oral medications
Anti-fungal topical creams
Antifungal dog shampoo

As your dog recovers from home, you shouldnt discontinue the prescribed medication if your vet hasnt asked you to even if the missing hair has grown back. Otherwise, the infection will reappear in no time.

It can take a few or several weeks for your dog to heal from ringworm. As they recover from home, consider the following:

Isolate them in a separate room so they dont leave their ringworm-infested hair all over the house. Even better, opt for a room that has minimal furnishing so that cleaning time isnt that hectic (its best if you clean that room daily to prevent hair-build up)
Deep clean all the places in the house (and things) where your dog has been prior to the ringworm diagnosis. You should thoroughly vacuum every area that has traces of your dogs hair and clean your vacuum cleaner with a disinfectant afterwards.
Clean their bedding with a disinfectant, and also disinfect their toys. Your vet can recommend an effective disinfectant.

How can I tell if my dog has ringworm?

As discussed earlier, you will notice circular, dry-looking bald hair spots. These round-shaped patches may be red if your dog has a serious ringworm infection.

How do I get rid of ringworm on my dog?

You should see the vet for professional treatment. Also, make sure to deep clean your house to get rid of your dogs fungus-carrying fur. These stray hairs can cause re-infection.