Aspergillosis in Cats: Symptoms, Diagnosis, Treatment and Prognosis

By Dr Duncan Houston

A cat with months of sneezing or nasal discharge may initially appear to have another upper respiratory infection. The situation becomes much more concerning when the discharge persists despite antibiotics, the face begins to swell or one eye starts bulging forwards.

Aspergillosis is uncommon in cats, but some forms are locally destructive and extremely difficult to treat. The fungus can remain within the nasal cavity, invade the tissues surrounding the eye or, rarely, spread to the lungs, nervous system and other organs.

The key is recognising the difference between uncomplicated nasal disease and invasive disease before the infection causes irreversible damage.

Quick Answer

Aspergillosis is a fungal infection caused by environmental Aspergillus spores. In cats, it most commonly affects the nasal passages and sinuses, but it can invade the eye socket, facial tissues, brain or other organs.

Persistent nasal discharge, nosebleeds, facial swelling, a bulging eye or unexplained neurological signs require prompt veterinary investigation. Sino-nasal disease can often be treated successfully with fungal-plaque removal and local antifungal therapy, while sino-orbital and disseminated disease have a much more guarded prognosis. (ABCD cats and vets)

Aspergillosis in Cats at a Glance

The distinctions below reflect current ABCD, Merck Veterinary Manual and Journal of Feline Medicine and Surgery guidance. (ABCD cats and vets)

Question	Practical answer
What causes aspergillosis?	Environmental fungi within the genus Aspergillus
How do cats become infected?	Usually by inhaling airborne spores
Is exposure common?	Yes. Spores are widespread, but clinical disease is rare
Which cats are most at risk?	Persian, Himalayan and other brachycephalic cats are overrepresented, although any cat can be affected
Must the cat be immunocompromised?	No. Sino-nasal and sino-orbital disease often occur without an identified systemic immune disorder
What are the main forms?	Sino-nasal, sino-orbital and disseminated invasive aspergillosis
What are the earliest signs?	Persistent sneezing, noisy nasal breathing and unilateral or bilateral discharge
What suggests invasive disease?	Facial swelling, a protruding eye, third-eyelid elevation, oral masses, vision loss or neurological signs
How is it diagnosed?	CT or MRI followed by tissue cytology or histology, fungal culture and molecular species identification
Can a nasal swab diagnose it?	No. Environmental contamination can produce misleading positive cultures
How is sino-nasal disease treated?	Fungal-plaque debridement plus local antifungal infusion, sometimes with systemic medication
Is treatment prolonged?	Yes. Treatment may continue for several months and sometimes much longer
Is it contagious?	No. Cats usually acquire it independently from the environment
What is the prognosis?	Usually favourable for non-invasive sino-nasal disease, but guarded to poor for invasive or disseminated disease

What Is Aspergillosis?

Aspergillus species are moulds found worldwide in soil, dust and decaying plant material.

Cats regularly inhale small numbers of fungal spores without developing disease. Normal nasal defences, mucociliary clearance and immune cells usually remove them before infection becomes established.

Aspergillosis occurs when spores adhere to respiratory tissue, form fungal hyphae and resist the cat’s local immune response. Depending on the species involved and the cat’s susceptibility, the fungal growth may remain on the surface of the nasal lining or invade deeply into surrounding tissues. (ABCD cats and vets)

Is Aspergillosis the Same as Ringworm?

No.

Ringworm is a superficial dermatophyte infection affecting hair, skin and claws. Aspergillosis is caused by a different group of fungi and usually affects the respiratory tract or deeper tissues.

Ringworm is readily transmitted between animals and people. Aspergillosis is generally acquired from environmental spores and is not considered contagious through ordinary contact with an infected cat. (Sage Journals)

What Are the Different Forms of Feline Aspergillosis?

1. Sino-Nasal Aspergillosis

Sino-nasal aspergillosis, or SNA, affects the nasal cavity and paranasal sinuses.

It is usually non-invasive. Fungal colonies form plaques that adhere to the nasal or sinus lining but do not extensively penetrate the deeper tissues.

A. fumigatus is the species most commonly associated with this form. Other species can occasionally produce similar disease. (ABCD cats and vets)

Typical signs include:

• Persistent sneezing

• Stertor or snoring-type nasal noise

• Unilateral or bilateral nasal discharge

• Mucous or pus-like discharge

• Nosebleeds

• Reduced airflow through one or both nostrils

• Occasional fever

• Enlarged lymph nodes beneath the jaw

• Less commonly, swelling over the nose or a visible nasal mass

The discharge may improve temporarily with antibiotics if there is a secondary bacterial component, then return because the fungal plaques remain.

2. Sino-Orbital Aspergillosis

Sino-orbital aspergillosis, or SOA, is the aggressive invasive form.

Fungal hyphae penetrate beneath the nasal lining, destroy bone and extend into the eye socket and surrounding facial tissues. The organisms most frequently involved include Aspergillus felis, A. udagawae and A. wyomingensis. These are cryptic species closely related to A. fumigatus but may respond very differently to antifungal medication. (ABCD cats and vets)

Signs may include:

• Swelling around one eye

• Exophthalmos, where the eye is pushed forwards

• Prolapse or elevation of the third eyelid

• Squinting

• Eye discharge

• Corneal ulceration

• Uveitis

• Facial swelling or distortion

• A mass extending into the mouth

• Ulceration of the hard palate

• Pain or difficulty opening the mouth

• Reduced appetite

• Difficulty swallowing

• Vision loss

Many affected cats have a previous history of chronic sneezing or nasal discharge before the orbital swelling becomes obvious. (ABCD cats and vets)

3. Disseminated Invasive Aspergillosis

Disseminated invasive aspergillosis occurs when the fungus enters blood vessels or lymphatic tissues and spreads beyond the original site.

Potentially affected areas include:

• Lungs

• Lymph nodes

• Kidneys

• Spleen

• Liver

• Vertebrae

• Brain and meninges

• Other soft tissues

Signs vary depending on the organs involved and may include fever, weight loss, marked lethargy, coughing, breathing difficulty, spinal pain, weakness or neurological abnormalities. Disseminated disease is rare in cats and is more often associated with immunosuppressive disease or treatment, although exceptions occur. (ABCD cats and vets)

4. Other Focal Forms

Rare isolated infections have been reported involving the:

• Cornea

• Ear canal

• Lung

• Urinary bladder

• Gastrointestinal tract

• Skin or subcutaneous tissue

These presentations require treatment directed at the specific site and the identified fungal species. (ABCD cats and vets)

How Do Cats Get Aspergillosis?

Cats usually become infected by inhaling environmental spores.

The spores enter the nasal passages and sinuses, where they may settle within mucus or damaged respiratory tissue. Most are eliminated. Disease develops only when the fungus successfully adheres, grows and evades local immune defences. (ABCD cats and vets)

A cat does not normally acquire aspergillosis by:

• Living with another infected cat

• Sharing food bowls

• Sharing a litter tray

• Being groomed by an infected cat

• Being scratched or bitten by an infected cat

Two cats in the same environment may both inhale spores, but the infected cat is not usually the source.

Which Cats Are Most at Risk?

Brachycephalic Cats

Persian and Himalayan cats are consistently overrepresented in reported upper respiratory aspergillosis cases.

Their shortened facial anatomy may reduce drainage and clearance of nasal secretions. Genetic differences in local antifungal immunity have also been suspected, particularly in cats of Persian ancestry. (ABCD cats and vets)

Other cats with Persian ancestry, including some Ragdolls, may also be overrepresented in invasive fungal case reports. This does not mean every brachycephalic or pedigree cat is high risk, or that domestic short-haired cats cannot become infected.

Cats With Nasal Damage or Disease

Reported contributing factors include:

• Previous facial trauma

• Nasal foreign material

• Chronic viral respiratory disease

• Nasal tumours

• Previous prolonged antibiotic treatment

• Impaired mucociliary clearance

These associations do not prove that one event caused the infection, but they may create damaged tissue in which inhaled spores can become established. (ABCD cats and vets)

Cats With Concurrent Disease

Reported concurrent conditions include:

• Diabetes mellitus

• Chronic kidney disease

• Hyperthyroidism

• Pulmonary cancer

• Immunosuppressive medication use

• Severe systemic illness

However, immunosuppression is not required for sino-nasal or sino-orbital disease. Cats that appear otherwise healthy can still develop invasive aspergillosis. Disseminated disease is more strongly associated with compromised immunity. (ABCD cats and vets)

What Are the Symptoms of Aspergillosis?

Nasal Signs

The most common early signs are:

• Sneezing lasting longer than expected

• Persistent nasal congestion

• Stertor or snoring sounds

• Discharge from one nostril

• Discharge from both nostrils

• Clear discharge becoming mucous or pus-like

• Blood from the nose

• Reduced sense of smell

• Reduced appetite because the cat cannot smell food

A chronic one-sided discharge, particularly when blood is present, warrants investigation for fungal disease, a foreign body, dental disease or cancer.

Facial and Orbital Signs

The most concerning signs are:

• Swelling beside or beneath an eye

• One eye appearing larger or farther forwards

• Third-eyelid prolapse

• Inability to close the eyelids normally

• A cloudy or ulcerated cornea

• Unequal pupils

• Eye pain

• Facial distortion

• A swelling in the roof of the mouth

• Difficulty chewing or swallowing

These signs suggest that disease may have moved beyond the nasal cavity. (ABCD cats and vets)

Neurological Signs

Extension through the skull or along adjacent tissues can cause:

• Blindness

• Seizures

• Circling

• Nystagmus

• Tremors or facial twitching

• Increased sensitivity to touch

• Poor coordination

• Behavioural change

• Reduced awareness

Central nervous system involvement is a major negative prognostic sign. (ABCD cats and vets)

Disseminated or Pulmonary Signs

Possible signs include:

• Fever

• Marked lethargy

• Weight loss

• Poor appetite

• Coughing

• Rapid breathing

• Laboured breathing

• Lameness or spinal pain

• Weakness

• Neurological abnormalities

These signs are nonspecific and can resemble cancer, FIP, bacterial infection, toxoplasmosis and several other systemic diseases. (ABCD cats and vets)

How Worried Should You Be?

Lower Risk

Your cat has:

• Mild sneezing

• Clear nasal discharge

• Normal appetite

• Normal breathing

• No facial swelling

• No eye pain

• Signs present for only a few days

What it may mean: A viral upper respiratory infection or temporary irritation is more likely than aspergillosis.

What to do: Monitor closely. Arrange veterinary assessment if signs continue beyond approximately seven to ten days, become one-sided or repeatedly return.

Moderate Concern

Your cat has:

• Nasal discharge persisting longer than one to two weeks

• Thick or foul-smelling discharge

• Repeated nosebleeds

• Noisy nasal breathing

• Reduced appetite

• Poor or temporary response to antibiotics

• Enlarged lymph nodes beneath the jaw

What it may mean: Chronic rhinitis, dental disease, fungal infection, a foreign body, a polyp or neoplasia is possible.

What to do: Arrange veterinary investigation within the next few days. Repeating another empirical antibiotic course without imaging or sampling may simply delay the diagnosis.

High Concern

Your cat has:

• Facial swelling

• A protruding eye

• Third-eyelid elevation

• Eye pain or corneal cloudiness

• A mass in the mouth

• Difficulty eating or swallowing

• Progressive weight loss

• Marked lethargy

What it may mean: Invasive fungal disease, retrobulbar infection or cancer may be present.

What to do: Seek same-day veterinary assessment and referral-level imaging where available.

Critical

Your cat has:

• Open-mouth breathing

• Severe respiratory effort

• Sudden blindness

• Repeated seizures

• Collapse

• Inability to stand

• Severe facial or eye pain

• Inability to swallow

• Minimal responsiveness

What it may mean: Airway compromise, severe orbital disease, brain involvement or disseminated infection may be occurring.

What to do: Attend an emergency veterinary hospital immediately.

What Else Can Look Like Aspergillosis?

Aspergillosis is rare, and several more common diseases cause similar signs.

Presentation	Important alternatives
Chronic nasal discharge	Feline herpesvirus, chronic inflammatory rhinitis, bacterial rhinitis
One-sided discharge	Foreign body, dental disease, polyp, tumour
Bloody discharge	Neoplasia, trauma, fungal disease, hypertension or clotting disorder
Facial swelling	Dental abscess, tumour, cryptococcosis, bacterial infection
Protruding eye	Retrobulbar abscess, tumour, salivary disease, orbital inflammation
Cloudy or painful eye	Corneal ulcer, glaucoma, uveitis, trauma
Neurological signs	FIP, toxoplasmosis, cryptococcosis, tumour, stroke
Weight loss and fever	Lymphoma, chronic infection, systemic fungal disease
Respiratory distress	Pneumonia, asthma, pleural effusion, heart failure, pulmonary tumour

Cryptococcosis is a particularly important fungal differential in cats because it more commonly causes feline nasal and systemic disease. CT findings alone cannot reliably separate aspergillosis from another fungal infection or from neoplasia, so tissue sampling remains essential. (ABCD cats and vets)

When Is This an Emergency?

Seek immediate veterinary treatment if your cat develops:

• Open-mouth breathing

• Pronounced abdominal breathing effort

• Blue, grey or very pale gums

• A rapidly enlarging facial swelling

• An eye that is protruding and cannot close

• A cloudy, ulcerated or ruptured-looking eye

• Sudden vision loss

• A seizure lasting five minutes or repeated seizures

• Collapse

• Inability to stand

• Severe disorientation

• Inability to eat or swallow

• Rapid deterioration over several hours

A protruding eye is not simply a cosmetic change. Exposure can rapidly damage the cornea, while the underlying mass may be destroying orbital bone or extending towards the brain. (ABCD cats and vets)

What To Do Right Now

1. Keep the Cat Indoors

Limit exposure to dust, soil, vegetation and further trauma while the cat is being investigated.

Indoor housing also makes it easier to monitor discharge, appetite, breathing and neurological changes.

2. Record the Pattern of Discharge

Take photographs and note:

• One nostril or both

• Clear, mucous, pus-like or bloody discharge

• Frequency of sneezing

• Nosebleeds

• Noisy breathing

• Changes in smell or appetite

A one-sided problem that becomes bilateral can indicate progressive disease.

3. Photograph Facial and Eye Changes

Use similar lighting and angles each day.

Monitor:

• Eye position

• Third eyelid

• Corneal clarity

• Pupil size

• Facial symmetry

• Swelling beneath the eye or jaw

Do not repeatedly press on the swelling or attempt to push a protruding eye backwards.

4. Prevent Eye Rubbing

Use an Elizabethan collar if the cat is rubbing or scratching the eye.

Orbital disease may prevent normal eyelid closure, creating secondary exposure keratitis and corneal ulceration.

5. Do Not Start Leftover Steroids

Corticosteroids can suppress antifungal immune responses and may worsen an undiagnosed invasive infection.

A cat with chronic nasal disease should not be placed repeatedly on immunosuppressive treatment without appropriate investigation when fungal disease remains a realistic possibility. (ABCD cats and vets)

6. Do Not Use Human Antifungal Medication

Antifungals differ substantially in:

• Feline absorption

• Tissue penetration

• Drug interactions

• Liver toxicity

• Kidney toxicity

• Neurological adverse effects

• Activity against individual Aspergillus species

The medicine must be chosen according to fungal identification, susceptibility testing and the location of infection.

7. Ask About Referral

A referral hospital may provide:

• CT

• MRI

• Rhinoscopy

• Sinuscopy

• CT-guided biopsy

• Fungal culture and molecular identification

• Ophthalmology

• Specialist surgery

• Therapeutic drug monitoring

Early referral is particularly important when orbital, neurological or systemic disease is suspected.

How Is Aspergillosis Diagnosed?

Complete Physical and Eye Examination

The veterinarian will assess:

• Nasal airflow

• Type and location of discharge

• Facial symmetry

• Eye position

• Third eyelid

• Corneal integrity

• Vision

• Oral cavity and hard palate

• Regional lymph nodes

• Neurological function

• Breathing and lung sounds

FeLV, FIV, diabetes and other concurrent diseases may also be investigated according to the cat’s history.

CT of the Head

CT is preferred over ordinary skull radiographs for upper respiratory disease.

It can identify:

• Destruction of nasal turbinates

• Soft-tissue material within the nasal passages

• Sinus involvement

• Fungal plaques or mineralised material

• Orbital masses

• Bone destruction

• Extension into facial tissues or the mouth

• Regional lymph-node enlargement

• Integrity of the cribriform plate

Imaging should ideally occur before rhinoscopy or biopsy because procedure-related bleeding can create artefacts. CT maps the disease and identifies the safest, highest-yield location for sampling. (ABCD cats and vets)

CT is highly useful, but it cannot confirm aspergillosis by itself. Cancer, cryptococcosis and other inflammatory diseases may produce similar changes.

MRI

MRI is particularly useful when:

• Neurological signs are present

• Brain or meningeal invasion is suspected

• Soft-tissue extension cannot be fully defined by CT

• Spinal disease is possible

MRI does not replace tissue diagnosis but helps determine the extent and urgency of invasive disease. (ABCD cats and vets)

Rhinoscopy and Sinuscopy

A camera may be passed into the nasal passages to look for:

• White, grey or green fungal plaques

• Necrotic tissue

• Turbinate destruction

• Masses

• Foreign material

• Abnormal mucus

Visible plaques should be sampled and removed where possible.

Cytology and Histopathology

A definitive diagnosis usually requires fungal hyphae to be demonstrated within inflammatory material or tissue.

Aspergillus typically forms narrow, branching, septate hyphae. Special stains such as PAS and Grocott methenamine silver improve visibility.

Microscopy can confirm fungal invasion, but it cannot reliably determine the exact Aspergillus species. (ABCD cats and vets)

Fungal Culture

Culture should be performed on:

• Fungal plaques

• Biopsy tissue

• Orbital granulomas

• Aspirated lymph nodes

• Samples from affected organs

A surface nasal swab is not enough. Aspergillus spores are common in the environment and may temporarily colonise the nasal cavity, so a positive swab culture can be incidental. Culture results must be supported by tissue invasion, plaques or compatible inflammation. (ABCD cats and vets)

PCR and Molecular Identification

Molecular identification is important because conventional fungal appearance may misidentify cryptic species as A. fumigatus.

PCR can distinguish organisms such as:

• A. fumigatus

• A. felis

• A. udagawae

• Other cryptic species

This distinction directly affects treatment selection and prognosis. (ABCD cats and vets)

Antifungal Susceptibility Testing

Susceptibility testing is strongly recommended for invasive and sino-orbital disease.

A. felis and related species may have:

• Poor susceptibility to itraconazole

• Poor susceptibility to voriconazole

• Better susceptibility to posaconazole

• Better susceptibility to terbinafine

• Better susceptibility to caspofungin

• Variable susceptibility to amphotericin B

The treatment plan should therefore be based on the individual isolate whenever possible. (Sage Journals)

Blood Tests and Serology

Routine blood abnormalities are nonspecific. Neutrophilia and increased globulins are among the more frequently reported findings.

Aspergillus-specific antibody testing can support a diagnosis of upper respiratory disease, but exposure and nasal colonisation may produce antibodies in cats without invasive infection. Serum galactomannan testing performs poorly in sino-nasal and sino-orbital disease and cannot rule infection out.

Serology should be considered supportive evidence, not a replacement for tissue sampling. (ABCD cats and vets)

How Is Sino-Nasal Aspergillosis Treated?

Successful treatment usually requires removing the fungal material rather than relying on tablets alone.

Endoscopic Debridement

Under general anaesthesia, the veterinary team removes visible fungal plaques and necrotic material using:

• Rhinoscopy or sinuscopy

• Suction

• Saline lavage

• Specialised grasping instruments

• Sinus access where required

Removing the fungal burden allows locally applied medication to contact the diseased tissues more effectively.

Local Antifungal Infusion

Clotrimazole or enilconazole may be infused into the nasal cavity and sinuses under anaesthesia.

The nose and throat must be carefully packed or catheterised to prevent leakage, aspiration and exposure of unintended tissues. The cat may need repositioning during the infusion to distribute the medication throughout affected spaces. (ABCD cats and vets)

Local treatment may not be appropriate when:

• The cribriform plate is damaged

• The infection has extended into the brain

• The necessary sinuses cannot be accessed safely

• The cat cannot tolerate anaesthesia

• Deep invasive disease is present

Repeat Procedures

One procedure may be curative in selected cats, but repeat debridement and topical treatment are sometimes needed.

A 2025 report described long-term resolution in two cats treated with enilconazole infusion followed by clotrimazole cream deposited within the frontal sinuses. This approach is promising but has not yet been evaluated in a large number of cats. (ABCD cats and vets)

Systemic Antifungal Medication

Oral antifungal medication may be added when:

• Fungal hyphae have invaded beneath the mucosa

• A cryptic species is identified

• Local treatment is incomplete or impossible

• Disease returns

• The infection has extended outside the nasal cavity

Itraconazole or posaconazole may be considered for appropriate sino-nasal infections, depending on species identification and susceptibility results.

Systemic treatment alone is often insufficient when significant plaques remain. In one reported group, cats treated only with oral itraconazole relapsed after treatment stopped. (ABCD cats and vets)

How Is Sino-Orbital Aspergillosis Treated?

Sino-orbital disease requires specialist management and should be approached as an invasive fungal infection.

Combination Antifungal Therapy

Current expert guidance commonly favours:

• Posaconazole with terbinafine

• Posaconazole, terbinafine and intravenous caspofungin in selected severe cases

• Amphotericin B-containing combinations when susceptibility results support its use

Itraconazole is not considered a reliable empirical choice for SOA because the cryptic species most often responsible frequently have intrinsic resistance. (Sage Journals)

Surgery

Possible procedures include:

• Debridement of orbital fungal granulomas

• Removal of necrotic tissue

• Orbital exenteration in selected cases

• Sampling or debridement through oral or facial approaches

Surgery may reduce fungal burden and relieve pressure, but current evidence has not shown that orbital surgery consistently improves overall outcomes compared with intensive antifungal therapy alone. Decisions must be individualised according to disease extent, vision, pain, fungal species and the cat’s general condition. (Sage Journals)

Why Voriconazole Is Usually Avoided

Voriconazole has caused severe neurological adverse effects in cats, including ataxia, cranial-nerve deficits and profound weakness.

Its pharmacokinetics are unpredictable in cats, so it is not currently recommended as a routine systemic treatment for feline SOA. A topical ophthalmic preparation may still be used for selected superficial corneal fungal infections under specialist supervision. (ABCD cats and vets)

How Is Disseminated Aspergillosis Treated?

Disseminated disease requires an individualised combination protocol guided by:

• Species identification

• Susceptibility testing

• Organs affected

• Neurological involvement

• Kidney and liver function

• Concurrent immunosuppression

• Ability to tolerate prolonged treatment

Treatment may include combinations of posaconazole, amphotericin B, terbinafine and an echinocandin such as caspofungin.

Supportive treatment may also include oxygen, nutritional support, analgesia, surgery for isolated lesions and management of the underlying immunosuppressive condition where possible. Evidence in cats remains limited primarily to case reports and small series. (OUP Academic)

How Long Does Treatment Take?

Treatment is rarely short.

For sino-nasal disease, systemic medication commonly continues for several months and may be maintained for at least one month after clinical resolution. Repeat rhinoscopy or imaging may be needed before treatment is stopped.

Successfully treated sino-orbital cases have received oral antifungals for four to eight months, while some cats have required treatment for several years because residual disease remained visible on CT. (ABCD cats and vets)

Stopping treatment based only on the disappearance of nasal discharge is risky. Clinical signs may improve before fungal material and invasive granulomas have fully resolved.

How Are Antifungal Side Effects Monitored?

Long-term antifungal treatment may cause:

• Reduced appetite

• Vomiting

• Diarrhoea

• Liver-enzyme increases

• Liver injury

• Kidney injury with some amphotericin formulations

• Skin reactions

• Drug interactions

• Neurological adverse effects with unsuitable medications

Monitoring may include:

• Complete blood count

• Liver enzymes

• Bilirubin

• Kidney values

• Urinalysis

• Body weight

• Appetite

• Therapeutic drug concentrations

• Repeat CT or endoscopic examination

Therapeutic drug monitoring is particularly valuable with posaconazole because absorption and blood concentrations vary between cats. (Sage Journals)

What Is the Prognosis?

Sino-Nasal Aspergillosis

The prognosis is generally good when:

• Disease remains non-invasive

• Plaques can be removed thoroughly

• Local antifungal therapy can be performed safely

• The causative species is susceptible

• Treatment continues for long enough

• Rechecks confirm resolution

Recurrence is possible, especially when treatment is stopped early or plaques remain. (ABCD cats and vets)

Sino-Orbital Aspergillosis

The prognosis is guarded to poor.

Older series reported successful cure in fewer than 20% of affected cats. More recent combination protocols, molecular fungal identification, susceptibility testing and therapeutic drug monitoring have produced successful outcomes in selected cases, but treatment remains prolonged, expensive and unpredictable. (ABCD cats and vets)

The outlook worsens with:

• Brain or meningeal involvement

• Vision loss

• Extensive bone destruction

• Dissemination

• Resistant fungal species

• Inability to administer or tolerate medication

• Delayed diagnosis

Disseminated Aspergillosis

The prognosis is generally poor.

Occasional cats have survived for prolonged periods with intensive combination treatment, but disseminated fungal invasion is difficult to eradicate and recurrence or progression is common. (OUP Academic)

Is Aspergillosis Contagious to People or Other Pets?

Aspergillosis is not normally transmitted directly from an infected cat to a person, dog or another cat.

The fungus is acquired from environmental spores. An immunocompromised person may face their own risk from dusty, mouldy or heavily contaminated environments, but ordinary contact with the affected cat is not considered the primary concern. (Sage Journals)

Routine precautions remain sensible:

• Wash hands after handling nasal discharge

• Wear gloves while cleaning contaminated material

• Keep wounds covered

• Dispose of soiled tissues safely

• Follow veterinary instructions after surgery or biopsy

The cat does not need infectious-disease isolation from household pets solely because aspergillosis has been diagnosed.

Can Aspergillosis Be Prevented?

Complete prevention is not possible because Aspergillus spores are widespread indoors and outdoors.

Risk reduction may include:

• Keeping high-risk or immunocompromised cats indoors

• Avoiding compost piles and visibly mouldy organic material

• Discarding mouldy food and litter

• Keeping food storage areas dry

• Maintaining good ventilation

• Managing diabetes and other chronic disease

• Using immunosuppressive medication only when clinically justified

• Investigating persistent one-sided nasal disease early

• Avoiding repeated empirical antibiotics or steroids without a diagnosis

There is no feline aspergillosis vaccine and no role for routine preventive antifungal medication. (ABCD cats and vets)

Indoor living reduces some environmental exposure but does not remove it completely because fungal spores are airborne and indoor cats can still develop invasive fungal disease. (Sage Journals)

Common Aspergillosis Mistakes

Assuming Every Chronic Nasal Problem Is Herpesvirus

Herpesvirus is common, but persistent one-sided discharge, bleeding, facial swelling or orbital change needs a broader investigation.

Repeating Antibiotics Without Obtaining a Diagnosis

Antibiotics may temporarily reduce secondary bacterial discharge while the fungal plaques continue destroying tissue.

Diagnosing Aspergillosis From a Nasal Swab

Environmental spores can contaminate or colonise the nose. Tissue invasion, plaques, cytology or histology must support the diagnosis.

Starting Corticosteroids Too Early

Steroids may worsen an unrecognised invasive fungal infection.

Treating Every Aspergillus Species the Same Way

Cryptic species causing sino-orbital disease may be resistant to itraconazole and voriconazole. Molecular identification and susceptibility testing matter.

Relying on Oral Medication Alone for Sino-Nasal Plaques

Debridement and local antifungal treatment are usually central to successful SNA management.

Stopping Treatment When the Discharge Improves

External signs may resolve before fungal disease has been eliminated.

Waiting After the Eye Begins To Bulge

Orbital invasion can cause corneal damage, blindness, bone destruction and central nervous system spread.

Frequently Asked Questions

Can an indoor cat develop aspergillosis?

Yes. Fungal spores are airborne and occur in indoor as well as outdoor environments. Indoor living lowers some environmental exposure but cannot eliminate risk completely. (Sage Journals)

Can nasal aspergillosis be cured?

Often, yes. Non-invasive sino-nasal disease has a generally favourable prognosis when fungal plaques are removed and local antifungal therapy is performed. Repeat treatment may be necessary. (ABCD cats and vets)

How long will my cat need antifungal medication?

Commonly several months. In invasive sino-orbital disease, treatment may continue for many months or even years, guided by examination, imaging, fungal susceptibility and drug monitoring. (Sage Journals)

Does a positive Aspergillus culture prove my cat is infected?

No. Aspergillus is widespread in the environment. Culture is most meaningful when the organism is grown from abnormal tissue or fungal plaques and fungal invasion is demonstrated by cytology or histology. (ABCD cats and vets)

Is facial swelling always sino-orbital aspergillosis?

No. Dental abscesses, bacterial infection, cryptococcosis, trauma and cancer can cause similar swelling. CT and tissue sampling are needed to establish the cause.

Final Thoughts

Aspergillosis is uncommon in cats, but recognising invasive disease early can make a major difference.

The most important points are:

1. Cats usually acquire aspergillosis by inhaling environmental spores.

2. Exposure is common, but clinical infection is rare.

3. Immunosuppression is not required for sino-nasal or sino-orbital disease.

4. Persian, Himalayan and other brachycephalic cats are overrepresented.

5. Sino-nasal disease usually remains within the nose and sinuses.

6. Sino-orbital disease invades the eye socket, facial tissues and bone.

7. Facial swelling or a protruding eye should never be dismissed as ordinary rhinitis.

8. Central nervous system involvement substantially worsens the prognosis.

9. CT should generally be performed before rhinoscopy or biopsy.

10. Tissue cytology or histology is needed to demonstrate fungal disease.

11. Culture alone can be misleading because Aspergillus is environmentally ubiquitous.

12. Molecular identification is important because cryptic species have different antifungal susceptibility.

13. Sino-nasal treatment usually requires plaque debridement and local antifungal infusion.

14. Systemic medication alone may not clear nasal fungal plaques.

15. Sino-orbital disease usually requires prolonged combination treatment.

16. Treatment may last months and occasionally years.

17. Early improvement does not mean treatment is complete.

18. Aspergillosis is not ordinarily contagious between cats or from cats to people.

19. Sino-nasal disease often has a good prognosis.

20. Orbital, neurological and disseminated disease remain difficult to cure.

The mistake that causes the greatest harm is continuing to treat persistent nasal discharge as an ordinary respiratory infection after the clinical pattern has changed.

When one side of the face swells, the eye moves forwards or the discharge repeatedly contains blood, the concern is no longer simply what is coming out of the nose. It is what may be growing and invading behind it.

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ASK A VET™ can help you organise nasal-discharge photographs, CT reports, biopsy results, fungal culture findings and antifungal monitoring records while you continue working directly with your cat’s veterinary team. A cat with open-mouth breathing, a protruding or severely painful eye, sudden blindness, seizures, collapse or difficulty swallowing still requires immediate hands-on veterinary care.