Introduction
Fungal infections are common health issues in cats. They occur when cats are exposed to fungi such as yeasts, molds, and dimorphic fungi. These infections can affect the skin, ears, mouth, respiratory tract, and other areas of a cat’s body. Some of the most common fungal infections in cats include ringworm, aspergillosis, candidiasis, cryptococcosis, and blastomycosis.
Fungal infections in cats often cause symptoms including hair loss, redness, itching, discolored patches on the skin, crusty skin lesions, thickening/flaking of the skin, and discharge. In some cases, especially if left untreated, fungal infections can even spread internally and become life-threatening. Fungal infections are spread through direct contact with an infected animal or from contact with fungal spores in the environment. Young, old, and immunocompromised cats are most at risk.
Common Fungal Infections
Some of the most common fungal infections seen in cats include:
Ringworm
Ringworm, caused by the fungus Microsporum canis, is highly contagious between cats, dogs, and humans. It causes circular areas of hair loss and scales or crusts on the skin. Ringworm is spread by direct contact with an infected animal or from surfaces contaminated with fungal spores.
Aspergillosis
Aspergillosis is caused by the fungus Aspergillus, which is commonly found in soil, organic debris, air conditioning systems, and ventilation ducts. Aspergillosis can affect the lungs, sinuses, eyes, skin, and central nervous system of cats. It causes respiratory illness and signs like sneezing, nasal discharge, difficulty breathing, and eye symptoms.
Cryptococcosis
The fungus Cryptococcus neoformans causes cryptococcosis, which often affects the brain and central nervous system. It can lead to neurological symptoms like personality changes, seizures, and head tilt or tremors. It is thought to be acquired through inhalation of fungal spores in the environment.
Blastomycosis
Blastomycosis is caused by the fungus Blastomyces dermatitidis and occurs in certain geographic regions, especially the Ohio and Mississippi River valleys. It causes pyogranulomatous skin lesions, eye inflammation, respiratory disease, or disseminated infections involving multiple organs.
Histoplasmosis
Histoplasmosis, caused by Histoplasma capsulatum, can occur when a cat inhales fungal spores from contaminated soil. It often causes respiratory symptoms like cough, fever, and difficulty breathing. Disseminated histoplasmosis affecting multiple organs can also occur.
Symptoms
Common symptoms of fungal infections in cats include:
Hair loss – Fungal infections can cause patches of hair loss. The skin in the affected areas may appear red and flaky.
Red, flaky skin – Fungi that infect the skin cause inflammation, leading to redness, scaliness, and flaking.
Sores – Skin fungi like ringworm cause round, red sores with a ring-shaped rash. The sores are often itchy.
Discharge – Fungal infections in the nasal passage, eyes, or other mucous membranes lead to abnormal discharge. This discharge may contain pus, blood, or other fluids.
Sneezing/coughing – Respiratory fungal infections cause sneezing, coughing, wheezing, and nasal discharge.
Lethargy – Systemic fungal infections that spread internally can cause fever, loss of appetite, and lethargy.
Other general symptoms include skin lesions, swelling, blindness, seizures, difficulty breathing, and more. Early diagnosis and treatment is key to relieving symptoms and preventing complications.
Causes
There are several potential causes of fungal infections in cats:
Exposure to infected soils, plants, and animals is a common cause. Fungal spores are present in many environments and can be inhaled or ingested by cats, leading to infection. Certain fungi like Cryptococcus are found in soil contaminated by bird droppings. Cats that go outdoors and hunt are at higher risk of exposure to fungal spores [1].
A weakened immune system also increases susceptibility to fungal infections. Conditions like feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) suppress the immune system. Kittens and senior cats may also have weaker immunity [2].
Allergies are another risk factor, as they can cause damage to the skin barrier and allow fungus to penetrate. Inhaling large amounts of fungal spores can also overwhelm the immune defenses in the respiratory tract [2].
Specific fungal infections have additional causes. For example, Sporothrix infection is caused by scratches and bites from infected animals. Candida infections often occur alongside other illnesses like diabetes that impair immune function [3].
[1] https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/fungal-infections-in-cats
[2] https://www.wcrah.com/site/blog-flat-rock-vet/2020/11/26/fungal-infections-cats
[3] https://www.guilfordjamestownvet.com/site/blog-greensboro-vet/2021/02/12/fungal-infections-cats
Risk Factors
Certain cats are more prone to developing fungal infections than others. Key risk factors include:
Outdoor cats – Cats that go outside are more likely to come into contact with fungi in the environment. Outdoor cats explore areas like soil, mulch, plant matter, and wooded areas where fungi thrive. This exposure puts them at higher risk of infection. [1]
Kittens and older cats – Kittens and senior cats tend to have weaker immune systems, making them more vulnerable to fungal infections. Kittens haven’t fully developed their immune function yet. Older cats suffer a decline in immunity as they age. [2]
Existing illnesses – Cats with pre-existing medical conditions like diabetes, cancer, or FIV have compromised immune systems. This immunosuppression leaves them susceptible to fungal infections their bodies can’t fight off as easily. [3]
Keeping cats indoors, nursing kittens and seniors through vulnerable periods, and managing illnesses appropriately can reduce the risk of fungal infections.
[1] https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/fungal-infections-in-cats
[2] https://www.wcrah.com/site/blog-flat-rock-vet/2020/11/26/fungal-infections-cats
[3] https://www.vmsg.com/site/blog/2021/07/30/fungal-infections-in-cats
Diagnosis
The diagnosis of a fungal infection in cats generally starts with a thorough physical exam by a veterinarian. The vet will inspect the skin, ears, and nails closely for any signs of infection. They may take skin scrapings or nail clippings to examine under a microscope for the presence of fungal organisms. Skin biopsies of affected areas may also be done.
Certain blood tests like a complete blood count and biochemistry panel can help check if the infection is systemic and impacting the internal organs. These tests look for abnormalities in red blood cells, white blood cells, platelets, and chemical markers like liver and kidney enzymes. Imaging tests like X-rays and ultrasound may reveal masses or abnormalities to target for biopsy.
Once samples are collected through skin scrapings, nail clippings or biopsy, they are sent to a laboratory for fungal culture. This is the most definitive way to diagnose the specific fungal organism causing the infection. The vet may also examine the samples under the microscope to visualize the fungus directly. With a confirmed diagnosis, the most effective antifungal treatment can be prescribed.
Some key references for this section:
https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/fungal-infections-in-cats
https://www.petmd.com/cat/conditions/skin/skin-fungal-infections-cats
Treatment
Treatment for fungal infections in cats often involves antifungal medications. According to the Merck Veterinary Manual, “An ointment or topical application may be useful in the treatment of oral or skin candidiasis. Your veterinarian may also recommend different drugs given by mouth, such as fluconazole, itraconazole, or terbinafine.”
Some common antifungal medications used to treat fungal infections in cats include:
- Fluconazole
- Itraconazole
- Terbinafine
- Ketoconazole
The specific medication, dosage, and length of treatment will depend on the type and severity of the infection. Oral medications may be prescribed for several weeks to months. Topical antifungal ointments and shampoos may also be recommended for skin infections.
In addition to antifungal drugs, your veterinarian may recommend immune boosting supplements or foods to help your cat’s body fight the infection. These may include probiotics, omega-3 fatty acids, and antioxidants like vitamin C and E.
In rare cases, surgery may be required to remove infected tissue that does not respond to medications. This may be an option for chronic ear infections or invasive fungal growths.
With prompt treatment, most fungal infections in cats can be cured. Work closely with your veterinarian to ensure your cat completes the full course of prescribed medication and follow all home care instructions.
Home Care
If your cat has a fungal infection, there are some things you can do at home to help care for your cat and prevent the infection from spreading:
Isolate infected cats: It’s important to isolate infected cats from other pets to prevent spreading the fungus. Set up the sick cat in a separate room with their own food, water, litter box, bedding, and toys. Be sure to wash your hands after handling the infected cat before interacting with other pets. Change clothes before going near healthy cats as well.
Disinfect environment: Thoroughly clean and disinfect any areas the infected cat has been using. Use a pet-safe disinfectant and follow label instructions. Disinfect food and water bowls, bedding material, litter boxes, toys, etc. Vacuum and mop floors and wipe down other surfaces the cat touches. This will help remove fungal spores and prevent reinfection.
Topical baths: Your vet may recommend antifungal shampoos or solutions for topical bathing of infected skin. Give medicated baths as directed. Let the antifungal soak into the coat for 5-10 minutes before rinsing. Be sure to dry the coat thoroughly. These baths can treat the infection and provide relief from itching.
Prevention
There are several ways you can help prevent fungal infections in your cat:
Grooming and hygiene – Keep your cat’s coat clean by regularly brushing and bathing. Check for any signs of skin irritation or infection. Trim hair around ears, paws, and rear to prevent overgrowth of yeast and fungus. Disinfect grooming tools after each use. Frequently wash bedding and disinfect litter boxes.
Limit outdoor access – Keep your cat indoors as much as possible. Outdoor areas like soil, grass, and forest floors harbor fungi and yeasts. Reduce the chance of exposure by limiting outdoor access. [1]
Reduce exposure – Avoid using shared grooming tools between animals. Isolate cats with fungal infections to prevent spreading. Disinfect any surface an infected cat touches. Consult your vet about probiotics that support healthy skin bacteria. Keep your cat’s immune system strong.
When to See a Vet
It’s important to see your vet if your cat’s fungal infection does not improve with initial treatment. Symptoms that persist or worsen indicate the infection is not under control. Specifically, you should schedule a veterinary visit if:
- The infection spreads or new lesions develop
- Your cat seems lethargic, refuses to eat, or acts ill
- Your cat excessively licks, scratches, or rubs the infected area
- You notice swelling, pus, a foul odor, or skin ulcers
- Your cat has a fever or seems otherwise unwell
Seeing the vet promptly when symptoms persist allows for a reevaluation of your cat’s condition. The vet can prescribe a change in medications, higher dosage, or different approach to get the infection under control. Delaying veterinary care risks the infection worsening and spreading.
It’s also crucial to schedule an appointment if you suspect a fungal infection in the first place. While some mild cases may clear up with over-the-counter treatment, the vet needs to diagnose the specific type of fungal or yeast infection through skin scrapings or culture. This ensures your cat receives the proper prescription antifungal medication. Attempting to treat a fungal infection without an accurate diagnosis can worsen your cat’s condition.