The first night home, and the dog would not walk inside

A typical scenario based on situations we commonly see. Names and details are illustrative.

Prae lives in a two-storey townhouse in Bang Bua Thong, Nonthaburi, with two mixed-breed dogs, Tua Dam and Kanompang, and a ten-year-old ginger cat called Som. When floodwater began creeping into the soi, she evacuated everyone to a relative's house in Pak Kret. She left the dog crates, the cushioned beds, the litter box, a half-used sack of kibble and a basket of toys downstairs, expecting the water to stay around ankle height. Instead it rose almost to knee level and sat there for nearly two weeks.

When the water finally drained away, Prae and her husband shovelled out the mud, scrubbed the floors with floor cleaner and bleach, and ran fans for days. On the evening of day four they brought the animals home. Tua Dam stopped dead at the front door, sniffed the tiles again and again, then backed out and lay down on the driveway. Som walked straight under the staircase and urinated on the exact spot where her litter box used to be. Kanompang started scratching that first night and did not stop.

The humans noticed it too. Every time the windows were closed, a smell rose from the floor: part damp mud, part old pet urine that had soaked into the grout years ago, part sour, mouldy kibble. Prae's husband began sneezing every morning, and their seven-year-old daughter came out in a red rash on her legs after sitting on the floor to play with the dogs. "We already cleaned," Prae said. "Why doesn't the house feel like ours again?"

It is the question countless pet owners ask after a flood. A home with animals is a harder problem than an ordinary house. There are long-established pet odours embedded in the building materials, there are pet belongings made of foam and fabric that soaked up floodwater like sponges, and there are four-legged family members who live at floor level, sniff everything, lick everything and groom constantly, so they pick up whatever is left on the ground far more readily than we do. This guide walks through what hides in a pet home after the water recedes, why ordinary cleaning often falls short, and where WHD's residential ozone disinfection service fits in, safely and in the right order.

The invisible problems in a pet home after flooding

Floodwater does not just bring mud. It carries sewage from overflowing drains, rat urine, animal droppings, carcasses and general waste from the whole neighbourhood. When it drains, that material stays behind in floor joints, under cabinets, inside cushions and deep in anything porous. In a home with pets, the risks fall into several groups.

1. Leptospirosis, which affects both people and dogs

Leptospirosis, known in Thailand as "rat urine disease", is caused by bacteria shed in the urine of rats and some other animals. The bacteria can survive for a long time in standing water and wet mud, and they enter the body through cuts, scrapes or the membranes of the eyes, nose and mouth. Dogs catch it too, because they wade through water, sniff and lick the ground. An infected dog may show fever, lethargy, loss of appetite, vomiting or yellowing of the eyes, and it can shed bacteria in its own urine, creating another route of exposure for the family.

In people, the warning signs are a sudden high fever, headache, muscle pain (especially in the calves) and red eyes after wading through floodwater or cleaning up. Anyone with these symptoms should see a doctor promptly and mention flood exposure. A dog showing unusual signs needs a vet just as quickly. Disinfecting the home reduces the source of germs in the environment; it does not treat infection in a person or an animal.

2. Mould in pet beds, cushions and rugs

Most pet beds are foam, polyester fibre and thick fabric: materials that hold a lot of water and dry very slowly. Mould can start growing within 24 to 48 hours of getting wet, which is exactly why the WHO and the US CDC advise cleaning and drying flooded areas within that window. Airborne mould spores make people with allergies or asthma sneeze and congest, and pets can develop itchy skin, hair loss or coughing as well.

Beyond airborne mould there is ringworm, a skin fungus many owners recognise as circular patches of missing fur on a cat or dog. Ringworm loves damp conditions, can pass from animals to people, and its spores can linger on cushions, carpets and corners for a long time. A humid house after a flood is practically an open invitation.

3. Bacteria in cages, trays, bowls and litter boxes

Crates have endless corners, and scratched plastic trays give grime somewhere to hide. Mix floodwater with old food crumbs, fur and dried urine and you have ideal conditions for gut bacteria such as E. coli and Salmonella. A litter box that went under becomes a lump of mud mixed with faeces. Handled carelessly, it spreads contamination across the whole floor.

4. Old urine odour that the water "wakes up"

Many owners are surprised that cat or dog urine smells stronger after a flood than before. The reason is that old urine deposits, long dried into grout lines, under laminate or along wooden skirting, break down again when they get wet and release ammonia all over again. Humidity also speeds up the bacteria that digest those deposits, so the smell becomes sharper and more persistent. And because pets smell far better than we do, they tend to return to any spot that smells like urine, creating the most exhausting cycle of all for owners.

5. External parasites that moved in during the flood

During a flood, small animals and insects flee to higher ground, and some end up indoors. Fleas, ticks and mites carried by stray animals or rats can remain in corners and crevices, and returning pets are their first target. Parasites must be managed with preventive products recommended by your vet, together with vacuuming and washing. Ozone helps with odour and microorganisms, but it does not replace parasite treatment on the animal itself.

Who is most at risk

• Young children who crawl and sit on the floor with pets, put their hands in their mouths and have developing immune systems.
• Older adults with chronic conditions such as diabetes, kidney disease or lung disease.
• Pregnant women, who should avoid cleaning litter boxes and flood waste themselves.
• People with allergies or asthma, sensitive to fur, mould spores and harsh chemical fumes alike.
• Senior pets, young animals and sick animals, such as cats with kidney disease, elderly dogs and puppies or kittens that have not finished their vaccinations.
• Birds and small caged animals like rabbits and hamsters, whose respiratory systems are especially sensitive to anything in the air.

What it costs when the house is not truly clean

Health: illness that bounces between people and pets

A pet home is a small ecosystem where people and animals share the same space. If the source of contamination is still there, illness tends to move in a chain. The cat develops ringworm on an ear and, soon after, a child has a round rash on an arm. Dad sneezes every morning because of spores in the dog bed next to the sofa. Mum gets an upset stomach after washing flood-soaked food bowls without gloves. None of this happens all at once; it builds until everyone feels the house is somehow "unwell" without knowing why.

Money: two sets of medical bills and repeat purchases

Pet owners after a flood often pay twice: for the family's doctor visits and for the vet. Antifungal cream for the cat, medicated shampoo, blood tests for the dog, plus new beds, crates and supplies. Put new things into a house that still harbours mould and within weeks they start to smell and spot too, so you pay again for no reason.

Why the usual fixes are not enough

Pouring bleach on everything. Bleach works well on smooth, hard surfaces at the right dilution, but it does not reach deep into foam, fabric fibres or wood grain. Its sharp chlorine smell irritates the noses of dogs and cats, which are far more sensitive than ours. Worse, mixing bleach with ammonia-based cleaners, or pouring it on urine stains that already contain ammonia compounds, can release gases harmful to the airways, a warning public health agencies repeat every flood season.

Relying on fans alone. Fans do dry surfaces faster, but they also blow mould spores and contaminated fur around the room. Moisture trapped under flooring or inside walls stays where it is.

Air fresheners and pet odour sprays. Most of these work by masking: adding a pleasant scent on top. The urine and musty odours are still there, and they return as soon as the fragrance fades. Some fragrances also irritate cats and birds.

Painting over mould. A very common shortcut. Fresh paint looks clean, but the mould underneath is alive, and before long it pushes the paint into bubbles and flakes and the black spots return.

Washing pet beds and drying them indoors. Thick beds dried in a damp room only dry on the outside. The core stays wet and becomes a fresh mould nursery. Many items that sat in floodwater for days are better thrown away than kept.

What these methods have in common is that they only work on surfaces within reach. After a flood, germs and odour are spread through the air, in corners, under furniture and inside porous materials. Effective disinfection needs something that reaches the whole volume of a room.

How WHD ozone disinfection works in a home with pets

Ozone (O₃) is a form of oxygen made of three oxygen atoms. It is a strong oxidiser. Released into a closed room, it breaks down the cell structures of viruses, bacteria and mould, and it breaks apart the molecules that cause odour, including musty smells and the lingering odour of pet deposits. Once its work is done, ozone naturally reverts to ordinary oxygen (O₂) and leaves no chemical residue on surfaces. That matters enormously in a home where animals sleep, walk and lick the floor every day.

Because ozone is a gas, it reaches under sofas, behind cabinets, into air gaps and crate corners that cloths and sprays cannot. According to the test results the company has had certified by Thailand's Department of Medical Sciences and Intertek (UK), WHD's ozone treatment eliminates viruses, bacteria and mould by 99.99%. You can see the documents on our certification page.

Just as important: ozone comes after mud removal, washing and drying. It does not replace scrubbing, throwing away ruined items, or medical and veterinary care. It is the finishing step that handles what hands and liquids cannot reach, so the house is genuinely ready to live in again.

Our process for pet homes

1. Consultation and assessment. We ask about floor area, number of rooms, the species you keep, where they sleep and toilet, and how high the water rose, so we can plan zones.
2. Readiness check. We confirm mud is out, surfaces are washed and reasonably dry, and badly damaged items such as soaked pet beds have been removed.
3. Preparing the space and moving out every living thing. All people and animals leave; fish tanks and plants go out; doors and windows are closed and air-conditioning is set as the team advises.
4. Filling the space with ozone. The generator runs until the concentration reaches the working level throughout the room.
5. Contact time. Ozone reacts with microorganisms and odour molecules for the set period. A typical cycle is about 30 minutes per zone.
6. Rest and ventilation. Ozone reverts to oxygen, windows and doors are opened, and the team tells you when it is safe to go back in.
7. Handover and aftercare advice. We explain humidity control, care of pet areas, and the right time to bring your animals home.

For a complete job, ozone can be combined with WHD's surface disinfection service. Ozone jobs of 15,000 baht or more also receive a free medical-grade disinfectant spray to keep your pets' high-use spots clean afterwards.

10 reasons pet homes should consider ozone after a flood

1. No chemical film on the floors your pets lick. Ozone turns back into oxygen, so nothing is left on floors, bowls or toys.
2. It tackles old urine odour woken up by moisture by breaking the odour molecules down rather than covering them with perfume, helping break the repeat-toileting cycle.
3. It reaches under sofas, behind cabinets and into crate corners, because it is a gas that fills the room.
4. It reduces airborne mould spores behind morning sneezing, congestion and allergies in people and pets.
5. It lowers the chance of ringworm spores lingering in cushions and rugs, as a step after washing and alongside your vet's treatment.
6. Tested by trusted bodies. According to the company's certified results from the Department of Medical Sciences and Intertek, it eliminates viruses, bacteria and mould by 99.99%. See the ozone disinfection service.
7. Fast and predictable. About 30 minutes per zone, so in many homes your pets only need to stay elsewhere for half a day.
8. It saves on repeat purchases, because new beds and crates are not placed into a house that will mould them again.
9. Fewer family arguments about the animals, once smell and allergy symptoms ease and it becomes clear the pets were never the real cause.
10. A professional team that understands pet homes, planning zones, timing and a safe return. Book through our residential ozone page.

Before and after: what changes in a pet home

Note: results vary with the level of damage, how well the home was cleaned and dried beforehand, and humidity control afterwards.

Example case: Prae's home with two dogs and a cat

An illustrative example to explain the process, not a review from an identified customer.

Back in Bang Bua Thong, after a week of trying everything, Prae contacted WHD on LINE and sent photos of the ground floor and the old crate and litter box spots. Before the appointment the team asked her to throw out the soaked foam beds and cat cushion, wash and sun-dry the metal crates and plastic trays, and scrub the urine-stained grout under the stairs.

On the day, Prae took Tua Dam, Kanompang and Som to her relative's house early in the morning. The team split the ground floor into three zones: the living room including the space under the stairs, the kitchen where the food bowls live, and the storeroom where the crates and food are kept. The washed crates were placed inside the rooms during treatment so the ozone could reach their corners. Each zone ran for a cycle of about 30 minutes, followed by rest and ventilation.

By early afternoon the team said it was safe to go back in. Prae says the first thing she noticed was that there was no smell at all: not a nice scent, just an emptiness in the air. She left the windows open for a while longer as advised and brought the animals home that evening. Tua Dam walked into the living room as if nothing had happened, and Som used her new litter box in its new location instead of returning to the stairs. Over the following week she kept humidity down and kept Kanompang's vet appointments for the itching.

Recovery checklist for pet homes: before and after ozone

Before you start cleaning

• Wear rubber gloves, boots and a mask; cover any cuts on hands and feet.
• Keep young children, pregnant women and pets away while mud is removed.
• Photograph the damage before discarding anything, in case you need it for assistance or insurance.

Sort your pet supplies

• Throw away: foam beds, thick cushions, plush and stuffed toys, kibble and treats whose bags got wet, wet cat litter, cardboard scratchers.
• Wash and keep: metal crates, plastic trays, stainless steel or ceramic bowls, nylon leads, hard rubber toys, plastic litter boxes.
• Wash bowls in soapy water, scald them if the material allows, and replace any that are cracked.

Dry the house

• Open doors and windows and point fans to push damp air outside, not around the room.
• Check under laminate, along skirting and on lower walls. If they are still wet, wait or use a dehumidifier before booking.

On treatment day

• Board every animal with family, a pet hotel or a clinic. Move fish tanks, bird cages and plants out of the house.
• Open cupboards and drawers you want treated, and bring washed crates into the room.
• Do not re-enter until the team confirms rest and ventilation are complete.

After treatment

• Ventilate a little longer before bringing pets home.
• Set up beds and litter boxes in new, dry, well-ventilated spots.
• Keep humidity under control and clean bowls and litter daily.
• Take pets for a check-up, vaccinations and parasite prevention as your vet advises.
• Watch everyone, human and animal. Fever, calf pain, diarrhoea or a rash that does not improve means a doctor or vet visit right away.

Frequently asked questions

Is ozone treatment dangerous for pets?

During treatment the ozone concentration is not safe for any living thing to breathe, which is why every person and animal must be out of the space first. Once ozone has reverted to oxygen and the rooms are ventilated, pets can return. The benefit is that no chemical residue is left on surfaces they will lick.

How long do my dog and cat need to stay elsewhere?

It depends on the number of zones. Each takes about 30 minutes plus rest and ventilation. Most average homes plan for half a day to a full day; the team will confirm timing at the assessment.

Will cat urine smell be gone for good?

Ozone is very effective on odour molecules in the air and on surfaces, but urine soaked deep into grout or under flooring should be scrubbed out first. If a cat keeps toileting in the wrong place, it may be a health or stress issue, so talk to your vet too.

Does ozone kill fleas and ticks?

Our service targets microorganisms, mould and odour. Fleas and ticks should be managed with vet-recommended products on the animal, plus regular vacuuming and washing of bedding.

I keep birds or fish. What extra preparation is needed?

Move bird cages and fish tanks out of the house entirely on treatment day. Birds are extremely sensitive to air quality, and aquarium water can absorb gas. Bring them back only after ventilation is finished.

My pet got sick after the flood. Will ozone help treat it?

Ozone reduces germs in the environment; it does not treat illness. An animal with fever, lethargy, loss of appetite, yellow eyes or diarrhoea needs a vet now, just as a person with fever and calf pain after wading needs a doctor.

Give every member of the family a clean home again, two legs or four

Free consultation, site assessment and a treatment plan timed around boarding your pets.

Book Ozone Disinfection for Your Pet Home

Call 065-556-6294 · LINE @whd268 · worldhealthdisinfection@gmail.com

Promotion: ozone jobs from 15,000 baht receive a free medical-grade disinfectant spray.

Related services

• Residential and building ozone disinfection
• Ozone cleaning service
• Disinfection spraying service
• Certificates and test results
• Contact us

References

• CDC: Floods – cleaning up safely and keeping pets safe
• WHO fact sheets, including leptospirosis and dampness and mould