Pets are often the first household members to show signs of mould exposure, they spend more time at floor level where mould spore concentrations are highest, they groom themselves and ingest spores that settle on fur, and they can’t tell you what’s wrong. If your dog or cat is showing unexplained respiratory symptoms, skin irritation, or lethargy, and you’ve noticed mould anywhere in the home, there’s a strong case for taking both to their respective specialists.
This guide covers what mould does to pets, how to recognise exposure symptoms, and what steps to take.
Why Pets Are More Vulnerable to Mould Than Adults
Household mould releases spores and, in some species, mycotoxins into the air. The concentration of airborne spores is highest in the lowest metre of a room, exactly where cats, dogs, rabbits and other small animals spend most of their time. A dog lying on the floor of a mould-affected bedroom is breathing air with a meaningfully higher spore load than the human sleeping in the bed above.
Pets also have:
- Faster respiratory rates, a dog breathes 15-30 times per minute compared to 12-18 for a resting adult, increasing the volume of contaminated air processed
- Grooming behaviour that deposits spores from fur and surfaces directly into the digestive system
- Smaller body mass meaning even low doses of mycotoxins represent a proportionally higher exposure
- Limited ability to signal distress beyond behavioural changes that owners may attribute to other causes
Mould Species That Pose the Greatest Risk to Pets
Not all mould is equally dangerous to animals. The species most commonly associated with adverse effects in pets include:
| Mould Species | Risk to Pets | Common Location |
|---|---|---|
| Stachybotrys chartarum | High, mycotoxins affect respiratory and neurological systems | Wet drywall, water-damaged materials |
| Aspergillus spp. | High, can cause systemic aspergillosis in dogs | Subfloor, ceiling voids, organic debris |
| Penicillium spp. | Moderate, respiratory irritant | Wall cavities, carpet underlay |
| Cladosporium spp. | Moderate, allergic responses | Window sills, bathroom tiles |
| Alternaria spp. | Low-moderate, respiratory irritant | Soil, organic material, outdoor surfaces |
Aspergillosis, infection caused by Aspergillus species, is worth specific mention. Dogs are significantly more susceptible to Aspergillus infection than cats or humans. Nasal aspergillosis is the most common form, affecting the sinuses and nasal passages, and can progress to systemic disease in immunocompromised animals.
Recognising Mould Exposure Symptoms in Dogs
Respiratory signs
- Persistent sneezing or reverse sneezing
- Nasal discharge (clear, yellow or bloody)
- Coughing or wheezing
- Laboured breathing or increased respiratory rate at rest
- Pawing at the face or nose
Neurological or behavioural signs (particularly associated with mycotoxin exposure)
- Tremors or muscle twitching
- Disorientation or loss of coordination
- Unusual lethargy or collapse
- Seizure-like episodes
Gastrointestinal signs (from ingesting spores through grooming)
- Vomiting or diarrhoea
- Loss of appetite
- Excessive drooling
Skin and coat signs
- Patches of hair loss
- Redness, scaling or crusty skin
- Excessive scratching or licking
Recognising Mould Exposure Symptoms in Cats
Cats are somewhat more resistant to Aspergillus infection than dogs but still vulnerable to respiratory effects and mycotoxin exposure. Signs include:
- Sneezing, nasal discharge, watery eyes
- Wheezing or coughing (sometimes mistaken for hairballs)
- Lethargy and reduced activity levels
- Loss of appetite
- Skin irritation, particularly around the face and paws
Cats exposed to mycotoxins from Stachybotrys may show neurological signs including incoordination and tremors.
Other Pets and Mould
Birds are extremely sensitive to airborne pollutants and respiratory irritants. A pet bird showing respiratory distress, tail bobbing (a sign of laboured breathing), or unusual lethargy in a mould-affected home should be seen by an avian vet immediately. Birds have a unidirectional respiratory system that doesn’t clear inhaled particles the way mammalian lungs do.
Rabbits and guinea pigs breathe rapidly and are sensitive to elevated spore counts. Respiratory signs are similar to those in cats and dogs.
Fish are not affected by airborne mould but can be affected if mould grows on aquarium hoods or if water quality is compromised.
What to Do If You Suspect Your Pet Has Mould Exposure
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Remove the animal from the affected environment immediately. Even if you can’t remediate the home right away, keep pets (and children) out of heavily mould-affected rooms.
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See a veterinarian. Describe the mould situation at home and the symptoms you’ve observed. Blood tests, nasal swabs and imaging can identify whether your pet has an active fungal infection or is showing inflammatory responses to spore exposure.
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Get a professional mould inspection. Understanding what species are present and where mould is located in the home is critical, your vet needs to know the exposure context, and you need to know the full extent of the problem. A mould inspection and testing appointment provides this.
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Arrange mould remediation. Symptomatic relief in pets is temporary if the mould source isn’t eliminated. After professional mould remediation, reintroduce pets gradually and monitor for symptom recurrence.
Keeping Pets Safe During Mould Remediation
During remediation, the home (or at minimum the affected areas) should be off-limits for all household members, including pets. The remediation process disturbs mould colonies, temporarily increasing airborne spore concentrations. Containment measures (negative air pressure, plastic barriers) are part of professional practice, but pets should not be in the property during active work.
Practical steps:
- Board pets with a vet, kennel or trusted contact for the duration of the work
- Bag and remove pet bedding, toys and food bowls before work begins, porous items may need to be discarded if heavily contaminated
- Wash pet food and water bowls thoroughly before reuse
- Wash fabric pet items that remained in the home on a hot cycle before returning them to the property
- After work, allow thorough airing and clearance testing before reintroducing pets
Mould Risk to Pets in the Illawarra Region
Illawarra’s humid climate, combined with the older housing stock in suburbs like Wollongong, Corrimal, Dapto and Berkeley, creates conditions where mould is a year-round risk rather than a seasonal one. Households with pets, particularly dogs spending extended time at floor level or cats that sleep in rarely-ventilated rooms, should be especially proactive about monitoring for mould.
If your home has had water damage from an east coast low, roof leak or burst pipe, mould can establish within 24-72 hours and reach levels that affect pets before it becomes visible to human residents.
Frequently Asked Questions
Can mould kill a pet? Severe or prolonged mycotoxin exposure can be life-threatening in pets, particularly birds, small animals and immunocompromised dogs or cats. Aspergillosis, if untreated, can progress to systemic infection with a poor prognosis. Most cases are caught and treated before reaching this point, but early veterinary attention and prompt home remediation are essential.
My vet says my dog has a respiratory infection, could mould in my house be the cause? Possibly. Fungal spores can directly infect respiratory tissue, and mould spore exposure can also impair immune function, making secondary bacterial infections more likely. If your pet has repeated respiratory infections without an obvious cause, and you have any mould in the home, it’s worth investigating both simultaneously.
Do I need to discard my pet’s bedding if there was mould in the house? It depends on the extent of contamination and the material. Hard-surface items (plastic bowls, metal crates) can be cleaned with appropriate antimicrobial solution. Fabric bedding that was in a heavily affected room, particularly if it has visible mould or a musty smell, is best discarded. The cost of replacement is low compared to the risk of reintroducing contaminated items.
Is mould fogging safe for pets? No antimicrobial fogging treatment should be applied with pets present. The room must be vacated, sealed, treated and ventilated before reoccupation. Reputable companies using mould fogging will advise on safe reoccupation timeframes, which typically range from 2-6 hours after ventilation.
My cat keeps sneezing, should I get a mould test? Sneezing in cats has many causes, including viral upper respiratory infections. However, if the sneezing started or worsened after a water event, if you’ve noticed a musty smell in the home, or if multiple household members (people and pets) have respiratory symptoms simultaneously, a mould inspection is a sensible step to rule out the environmental cause.
Concerned about mould in your Illawarra home and its effect on your pets? Contact Illawarra Mould Removal for a professional inspection that tells you what you’re dealing with and how to fix it.