Cat Fungal Infections: 10 Types You Should Know
Cat fungal infections are caused by fungi, which are parasitic, spore-producing organisms that generally live in soil. These organisms cause infections in cats when inhaled, ingested, or passed into the skin through a wound or scratch.
Skin fungal infections, such as ringworm, are common, but other types of fungal infections in cats are rare. In fact, only 7 in 10,000 cats seen at university teaching hospitals in North America are affected by systemic fungal infections that impact respiratory systems and internal organs [1].
Causes of Fungal Infections in Cats
Cats can develop fungal infections when the fungus is inhaled, ingested, or passed into the skin through a wound or scratch.
Most commonly, they cause itchy, sore, uncomfortable lesions on the skin. Rarely, fungal infections cause respiratory illness or gastrointestinal symptoms such as vomiting or diarrhea.
Here is a closer look at how cats get fungal infections:
Inhalation
Cats explore their surroundings with their noses and sense of smell. This means felines can inhale and breathe in fungus while sniffing in the dirt, hunting, or rolling on the ground.
Ingestion
Our feline friends might ingest fungus during hunting or by eating soil-contaminated prey. They may also groom spores off of their coat or the coat of another infected cat.
Skin wounds
Fungal skin infections are the most common type of cat fungal infections. This happens when fungal spores enter the body through a break in the skin or a wound. It is important to keep wounds clean to prevent any type of infection.
Cat fungal infections related to nail injuries are also common. This is due to the proximity of the nails to the ground and the high chance of contact with soil and dirt.
How Do Indoor Cats Become Infected?
Fungal spores are widespread in the environment and can be brought into the home by humans, objects, or other animals. These spores can remain in the environment for years. This means our indoor cats aren’t entirely safe from fungal infections.
Are Certain Cats at Greater Risk?
Healthy cats are usually able to fight off fungal infections. But younger, older, or immunocompromised cats are more likely to suffer symptoms and become unwell. Outdoor cats are at higher risk of contracting fungal infections due to their lifestyles and activities.
Fungal infections “prey” on those with weakened immune systems. Cats with health conditions such as diabetes, Cushing’s disease, hyperthyroidism, and FIV may be more susceptible.
Certain medications, including some antibiotics or steroids, prevent a cat’s immune system from being as efficient as it should be. Therefore, cats taking these medications are more likely to suffer from fungal infections than cats that are not on medications.
Symptoms of Cat Fungal Infections
Symptoms of feline fungal infections depend on the type of fungus, route of infection, and whether or not the infection has the ability to spread throughout a cat’s body.
In general, symptoms of cat fungal infections may include :
- Fur loss
- Coughing
- Anorexia (loss of appetite)
- Itching
- Skin rashes
- Difficulty breathing
- Vomiting
- Discomfort
- Diarrhea
Fungal infections of the skin are the most common type of fungal infection seen by veterinarians. These infections can cause fur loss, itching, discomfort, and pain. These infections tend to be localized to the skin, nails, or ears. They can also be zoonotic (passed from cats to humans).
Fungal infections that attack the respiratory system commonly cause fever, coughing, and difficulty breathing. These can spread to other areas of the body, causing generalized disease.
Fungal infections that attack the gastrointestinal system commonly cause pain, anorexia (loss of appetite), diarrhea, and vomiting.
10 Fungal Infections in Cats
| Type of Fungal Infection | Nasal / Respiratory | Gastrointestinal | Skin Infection | Generalized / Systemic Infection | Zoonotic Risk |
| Dermatophytosis (Ringworm) | X | X | |||
| Malassezia | X | ||||
| Sporotrichosis | X | X | X | X | |
| Rhinosporidiosis | X | X | |||
| Nasal Aspergillosis | X | ||||
| Disseminated Aspergillosis | X | X | X | ||
| Cryptococcus | X | X | |||
| Blastomycosis | X | X | X | ||
| Histoplasmosis | X | X | X | X | |
| Candidiasis | X |
Dermatophytosis (Ringworm)
Type: Skin
Ringworm in cats is not caused by a worm but by a fungus. This type of fungus infects by entering the skin through a wound.
Ringworm presents as characteristic ring-like lesions on the skin in areas of hair loss.
It is extremely contagious and spread by direct contact with infected animals or surfaces, such as bedding.
Symptoms include flaky and itchy skin, brittle nails, and hair loss.
Ringworm is a zoonotic disease, so infection can pass between animals and humans.
Malassezia
Type: Skin
This is a relatively common fungal infection in cats. It is caused by an imbalance and subsequent overgrowth of the natural fungus that lives on the skin.
Malassezia is a fungus well known for causing nail bed infections and ear infections in cats.
Infection is most commonly seen in cats who hunt in wet, boggy conditions or in breeds with excessive skin folds or floppy ears.
Symptoms include skin that is itchy and flaky, red and irritated, and greasy. This fungal infection also produces a characteristic strong odor.
Veterinarians diagnose this infection by cytological examination of a swab of the infected skin under a microscope.
Treatment is with topical and/or oral antifungal medications. Sometimes shampoos, washes, or wipes may be appropriate to help keep infections at bay.
Malassezia is not zoonotic and cannot be passed between cats and people.
Sporotrichosis
Type: Skin
Sporotrichosis is a fungus commonly found in soil vegetation and timber. It is largely found in coastal regions, rivers, and valleys. Infection occurs by fungus penetrating a cat’s skin via a wound.
Infection can be spread in a cat’s lymph system, within the skin itself, or it can disseminate throughout the body.
This cat fungal infection causes lesions around the head, especially the bridge of the nose and ears. It is uncommon for the infection to spread throughout the body, especially if pet parents seek early treatment. If the infection does spread, symptoms can include fever, listlessness, and depression.
Diagnosis is made by biopsy or culture (sampling the lesions and microscopic examination).
Treatment is usually topical antifungal creams such as itraconazole or terbinafine. Sometimes surgical removal or cryotherapy is used.
The infection is zoonotic and most commonly transmitted by cat bites or scratches.
Rhinosporidiosis
Type: Respiratory
This is an uncommon fungal infection in the US. Inhaled fungal spores affect the lining of the nasal passages and occasionally the skin.
Infection appears like soft, pink, crumbly, polyp growths that obstruct the airways in a cat’s nasal passages.
Symptoms include a chronic bloody nasal discharge, nasal swelling, sneezing, wheezing, difficulty breathing, and discomfort.
A biopsy (sampling the lesions) is used to diagnose this infection.
Treatment is usually surgical removal of the polyp lesions, but recurrence is common. Antifungal medication may be prescribed after surgery to attempt to prevent reoccurrence.
The infection is not zoonotic.
Nasal aspergillosis
Type: Respiratory
This fungus typically grows on decaying leaves, vegetation, and compost piles.
Infection is caused by inhaling fungal spores directly into the nasal passages and sinuses. While the infection is typically confined to the nasal passages, it can spread to the nearby structures of the head. This type of infection is more common in long-nosed cats.
Symptoms include nasal pain, a chronic bloody nasal discharge, nosebleeds, sneezing, and snoring.
Diagnosis is made by visualizing lesions with rhinoscopy (viewing with a small camera), and biopsy (sampling the lesions).
Treatment can be difficult due to the location of the lesions deep within the nose and sinuses. Surgical removal may be an option alongside antifungal creams infused into the nose and oral antifungal medications. Recurrence is common due to the difficulty in accessing the sites of infection.
This fungal infection has the potential to be zoonotic, but the risk is considered low with good personal hygiene.
Disseminated aspergillosis
Type: Respiratory
Although very rare, sometimes Aspergillosis fungus causes a systemic (body-wide) type of infection which can affect multiple organs.
The fungus is inhaled and then can travel to other parts of the body in the bloodstream. Areas of the body in which infection sets up, seem to be species-dependent. In cats, the lungs, central nervous system, vertebrae (bones of the spine), gastrointestinal system, and kidneys are attacked more frequently.
Symptoms can include coughing, breathing difficulties, loss of appetite, vomiting, diarrhea, muscle wasting, or weakness. However, other more localized symptoms might include neurological signs, back pain, or lameness.
Diagnosis of this feline fungal infection is a little more difficult. It may involve X-rays, ultrasound scans, or CT scans to view the internal organs.
Treatment includes oral antifungal medications. It is often long-term and can be expensive.
The prognosis for this infection is guarded to poor.
Zoonosis is possible, but the risk is considered low with regular hygiene.
Cryptococcosis
Type: Respiratory
Although a rare infection, this type of fungal infection is the most common systemic fungal infection in cats (affecting internal organs).
Initially, the fungus is inhaled, usually from areas heavily soiled with bird feces. But it can also be found in decaying vegetation.
Inhaled fungal spores affect the lining of a cat’s nasal cavity first, but then can spread throughout the body from there. There are 4 forms of this infection: nasal, nervous system, skin, and systemic (body systems/ organs). The most common is the nasal form.
Symptoms include nasal discharge, swelling of the nose and face, sneezing, wheezing, difficulty breathing, deep non-healing wounds on the nose, visible masses in the nose, lethargy, and then potentially seizures, or other neurological complications.
Diagnosis can be made via a laboratory test known as Latex Agglutination Test (LAT), on blood, urine, or spinal fluid. Biopsies of affected tissues may also be necessary.
Treatment is usually surgical removal of the lesions and oral antifungal medications until the LAT test is negative or for 2-4 months past the resolution of any clinical signs.
The infection is not zoonotic.
Blastomycosis
Type: Respiratory, Skin
Blastomycosis is a type of infection that can be found in waterlogged areas such as lakes, marshes, ponds, and estuaries.
Cats breathe in the fungal spores and they initially affect the lungs. The infection can then spread out and affect the rest of the body, such as the bone marrow and brain. This type of fungus can also cause infection by invading the skin through a wound or injury.
Symptoms of systemic disease include difficulty breathing, lethargy, weight loss, cough, fever, and neurological changes.
Symptoms of skin disease include fur loss, discomfort, and skin lesions often resulting in nail bed infections or infections on the paws.
To diagnose this type of fungal infection, veterinarians exam the affected tissue with a microscope. A blood test is available in dogs but not yet widely used in cats.
Treatment for systemic disease is a prolonged course of oral antifungal medications.
Treatment for skin lesions can be topical antifungal creams/shampoos and/or oral antifungal medications.
This infection is not zoonotic.
Histoplasmosis
Type: Respiratory, Gastrointestinal
Found in the soil, this fungal infection is generally transmitted in the feces of birds and wild animals.
The infection is usually inhaled or sometimes ingested. Fungus usually affects the respiratory system initially before potentially spreading and becoming a systemic infection affecting other body organs.
Symptoms include lethargy, weight loss, loss of appetite, fever, cough, trouble breathing and skin masses.
Diagnosis is usually made by examination of affected tissues under the microscope.
Treatment involves oral antifungal medications for an average of 6 months.
Candidiasis
Type: Gastrointestinal
Candidiasis is a rare fungal infection in cats but common in birds.
Infection is by ingestion of the fungus. This type of fungus affects the mucous membranes, the skin, and the gastrointestinal tract.
Symptoms include diarrhea, weakness, and skin lesions.
To make a diagnosis, veterinarians examine swabs of skin lesions under a microscope.
Treatment includes application of topical antifungal creams and oral antifungals.
This type of infection is not considered zoonotic.
How to Treat Fungal Infections in Cats
Treatment for fungal infections in cats will depend on the specific diagnosis and type of fungus.
Generally, feline fungal infections are treated with:
- Topical creams
- Baths
- Medicated wipes
- Oral antifungal medication
Sometimes a mixture of all types of treatment are given to control the infection, especially if the infection is widespread.
For cat fungal infections that are localized to one particular area of skin, a topical cream may be appropriate. For those that spread throughout the body, oral medication may be necessary. The duration of the medication will depend on the type and severity of the infection.
Fungal infections in cats can be difficult to treat due to the inaccessibility of certain infection sites (nasal passages, internal organs, etc.) or due to chronic underlying factors (such as certain diseases or a cat’s age).
You and your veterinarian must work together to achieve a diagnosis and formulate a treatment plan to best manage your cat’s fungal infection.
Antifungal Medications for Cats
There are a variety of veterinary-prescribed antifungal medications for cats. These include oral medications, topical medications and wipes, and antifungal shampoos. Your veterinarian can direct you to the best medication for cat fungal infections.
Itrafungol (Itraconazole)
This is an oral solution given by mouth or in food. This medication is licensed for the treatment of ringworm in cats.
Fluconazole (Diflucan)
This is a tablet or solution medication used off-label by veterinarians (it is licensed for humans but not labeled for use in cats). It is commonly used to treat many of the fungal infections we have discussed. It is often the first choice for systemic infections and can also be used to treat skin, ear, and nail bed infections.
Ketoconazole
This medication is rarely prescribed in cats due to the risk of causing liver failure. It may be the active ingredient in some topical medications or wipes, so discuss its use with your veterinarian.
Malaseb Shampoo
This is an antibacterial and antibiotic shampoo used to treat skin, and nail infections in cats (if they comply).
Animax Ointment
This is a topical cream that is applied directly to the skin. It is a combination of antifungal medication, antibiotic, and a steroid.
TrizUltra + KETO Solution
This is a topical cleansing flush used to treat fungal ear infections or skin affected by fungus.
Mal-A-Ket Wipes
These are antifungal wipes that are particularly useful to use on cats with excessive skin folds. These can keep away fungal growth, preventing recurrent infections.
How to Prevent Fungal Infections in Cats
There are a few measures that pet parents can take to prevent fungal infections in cats.
Practice regular grooming. Consistent grooming allows you to examine your cat’s skin, nails, and ears to ensure there are no lesions, areas of hair loss, redness, scaling, or soreness. Pay particular attention to cats with excessive skin folds.
Keep your cat on parasite prevention. Keeping up to date with parasite control is essential to ensure your cat’s coat remains in tip-top condition. This prevents scratching and skin wounds that may develop into fungal infections.
Keep a close eye on your cat’s health. Monitor your cat’s overall health. Take note of any new behaviors or symptoms such as sneezing, nasal discharges, wounds, hair loss, or digestive upset. Speak to a veterinarian if you have concerns.
Consider your cat’s diet. Diet or food supplements (such as those containing essential fatty acids) may be useful if your cat has an underlying food allergy or poor skin structure leading to a weak skin barrier. Your veterinarian will discuss food trials and any appropriate supplementation.
Keeping Yourself and Your Cat Healthy
Some of the fungal infections discussed here can be passed between you and your cat. So, it is prudent to make sure you seek medical advice if you notice any new symptoms in you or your feline family member.
Maintain good personal hygiene routines – especially if treating your cat – to prevent passing a fungal infection to yourself or others.
Speak to your veterinarian if you have concerns about your cat and be vigilant in monitoring your cat’s health regularly.
References:
- “Infectious Diseases.” The Cat (2012): 1016–1089. doi:10.1016/B978-1-4377-0660-4.00033-8
