The Wysiwash treatment, explained
What hospital-grade hypochlorous acid actually is, and why we use it on every visit.
First, we're sorry. If you're reading this, you've probably just been through one of the worst weeks of pet ownership, and you're already thinking about the dog after the one you lost. That's not callous. That's the right thing to be thinking about. Because parvovirus doesn't politely leave when the dog does.
Canine parvovirus is one of the hardiest pathogens in veterinary medicine. It can live in your soil, on your fence, in your kennel runs, and in shaded corners of your yard for up to twelve months. Bleach kills it. Sunlight slowly degrades it. Freezing winters don't reset the clock the way most people hope. So before another puppy comes home, the yard has to do its share of the healing.
The short answer
Assume your yard is contaminated for twelve months. Disinfect what you can, wait out what you can't, and bring home only fully vaccinated dogs until the clock runs.
Section 01How parvo lives in your yard
Parvovirus is a non-enveloped virus, which is the technical way of saying it doesn't have a fragile fatty outer layer to break down. That's why it shrugs off most household disinfectants, dryness, and freezing temperatures that would kill other pathogens within hours.
Once an infected dog sheds parvo in their stool, the virus binds to soil, grass, gravel, concrete, and porous surfaces. From there:
Bare soil & shaded grass
Up to 12 months
The longest-lived environment. Shade, moisture, and organic matter all protect the virus.
Concrete & sealed surfaces
1–5 months
Easier to disinfect, bleach can actually contact the virus.
Direct sun, dry conditions
5 months on average
UV degrades parvo, but slowly. Don't count on a single hot summer.
Frozen ground
Pauses, doesn't kill
Utah winters preserve the virus rather than destroy it. Spring thaw can reactivate exposure.
One pile, every corner of the yard
Parvo doesn't stay where the pile was. Dog paws, your shoes, rain runoff, and squirrels all carry it across the yard within days. Treat the entire property as contaminated, not just the spot.
Section 02Month 0 · The first 72 hours
Day 0–1
Remove everything porous
Bedding, soft toys, fabric collars, rope leashes, the dog bed liner, food and water bowls (if plastic), and any soft items in the kennel area. These can't be reliably disinfected. Bag them and discard.
Day 1–2
Pick up every remaining stool
Double-bag and dispose in sealed trash, not yard waste, not compost. Wear disposable gloves. Wash hands before touching surfaces inside the home.
Day 2–3
Bleach all hard surfaces
Concrete patios, kennel runs, plastic crates, sealed flooring, metal gates and latches: scrub with a 1:30 bleach solution (about ½ cup bleach per gallon of water). Let it sit for 10 minutes before rinsing. Repeat after 24 hours.
Every time
Disinfect any shoes that have been in the yard
Parvo travels home on the soles of your shoes. Keep a dedicated pair of yard shoes if possible, or scrub soles with a 1:30 bleach solution and let them air-dry before going back inside. Do this for the full twelve-month window, not just the first week.
Day 3
Treat the soft yard with the right chemistry
Bleach destroys grass and fails on organic surfaces, it is consumed by organic matter before reaching the virus. For grass and soil, use Virkon-S (potassium peroxymonosulfate) at 1% concentration with a mandatory 10-minute dwell time. It is the only disinfectant class that retains meaningful activity in the presence of organic matter. Important: complete parvo elimination from grass and soil is not achievable by any product, but Virkon-S meaningfully reduces viral load on organic surfaces where other products fail entirely. Focus application on shaded corners and high-traffic dog zones.
Section 03Months 1–3 · Deep sanitation
This is the active phase. Your goal is to reduce viral load aggressively while the yard is still freshly contaminated. Three habits, every week:
- Disinfect every pair of shoes that has been in the yard. Bleach the soles (1:30) or keep a dedicated pair of yard-only shoes by the back door. Parvo on the soles of your shoes is the most common way it ends up on the kitchen floor.
- Weekly waste removal from any visiting or remaining dogs. Don't let anything sit. Even healthy dogs can shed parvo asymptomatically for weeks after exposure.
- Bi-weekly Virkon-S application on grass and soil zones at 1% concentration with 10-minute dwell time. Potassium peroxymonosulfate is the best available chemistry for organic surfaces, it retains activity in the presence of grass and soil where bleach and hypochlorous acid fail. It does not fully eliminate parvo from soil, but meaningfully reduces viral load with each application. Focus on shaded areas, high-traffic dog zones, and areas where fecal matter was present.
- Bi-weekly Wysiwash application on all hard surfaces: patios, kennel runs, concrete, and decking. Wysiwash fully decontaminates non-porous surfaces and handles ongoing bacterial load across the full yard.
- Monthly hard-surface bleach refresh for patios, kennel runs, and concrete pathways as additional belt-and-suspenders coverage.
About sunlight and rain
Both help. UV degrades parvo over time. Hard rain washes viral particles deeper into soil where dogs are less likely to ingest them. Neither is a substitute for active disinfection, but they're working with you in the background.
Section 04Months 4–9 · The waiting period
By month four, the worst is over, assuming you've kept the cleanup consistent. Viral load is dropping. Most contaminated surfaces should be sanitized to safe levels. But soil is the slow one, and the next dog isn't worth rushing.
What to do during this phase:
- Maintain the disinfection schedule. Don't taper.
- Avoid hosting unvaccinated dogs, especially puppies. No play dates. No daycare drop-offs.
- If you must walk a current dog through the yard, keep them on hard surfaces where possible and wipe paws with a damp cloth before re-entering the home.
- If you're considering tearing out the lawn and re-sodding, this is the window. Removing topsoil to about 4 inches eliminates the bulk of remaining viral particles. Cost-prohibitive but effective.
Section 05Months 10–12 · Bringing a dog home
You're almost there. The decisions you make in this final stretch matter most, because they determine whether your next dog inherits a clean yard or a delayed second tragedy.
Choose the right next dog
Fully vaccinated adults only for the first six months back. Puppies under 16 weeks, even with first vaccines, are still at risk. A vaccinated adult dog is the safest first resident of a post-parvo yard.
Final pre-arrival checklist
| Step | Why | Status |
|---|---|---|
| Confirm 12 months since last shed | Outermost edge of parvo soil viability | Required |
| Final Virkon-S treatment on all grass and soil areas | Best available chemistry for organic surface viral load reduction, applied at 1% with 10-minute dwell time | Required |
| Final Wysiwash treatment on all hard surfaces | Complete decontamination of concrete, pavers, kennel runs, and decking | Required |
| Replace soft items: beds, bowls, toys | Anything stored over the year may be contaminated | Required |
| Re-bleach hard surfaces a final time | Belt-and-suspenders peace of mind on non-porous surfaces | Recommended |
| Verify new dog's vaccine series complete | Especially DA2PPV (includes parvo), vaccination is the primary protection | Required |
| Have a vet-approved emergency plan | Know the symptoms, know the clinic | Required |
"The next dog doesn't deserve to inherit the last dog's illness. The whole point of the waiting year is to make sure they don't."
Scoopie protocolSection 06Five mistakes to avoid
- Trusting "natural" disinfectants. Vinegar, hydrogen peroxide at household concentrations, and essential oils do not kill parvo. Only specific EPA-registered products with correct concentration and dwell time work, and even then, only on the appropriate surface types.
- Using bleach on grass. Bleach fails on organic surfaces, it is rapidly consumed by organic matter before it can reach the virus. Bleach is appropriate for concrete and hard surfaces only. For grass and soil, Virkon-S is the best available option.
- Hosing the yard "clean." Water spreads viral particles. It does not destroy them.
- Bringing a puppy home at six months. Even with vaccines, puppies remain vulnerable. Wait the full year, or wait for a fully vaccinated adult.
- Reusing the dog's belongings. Hard items can be bleached or treated with Wysiwash. Soft items cannot be reliably disinfected. Discard generously.
- Skipping the patio. Concrete looks innocent and isn't. It is one of the surfaces parvo lives on longest, and one of the few surfaces it can actually be fully eliminated from with proper disinfection.
This article is for general education and is not a substitute for veterinary advice. If you've lost a dog to parvo or suspect exposure, speak with your veterinarian about your specific yard, climate, and household before bringing a new dog home. Timing estimates above reflect AAHA, AVMA, and Cornell veterinary literature; actual viral persistence varies with conditions. Complete elimination of parvovirus from organic surfaces including grass and soil is not achievable by any product or service, this is confirmed by UC Davis Koret Shelter Medicine Program. Disinfectant recommendations reflect best available evidence for viral load reduction on each surface type. Vaccination remains the most reliable protection against parvovirus.
