Last updated: 27 September 2026
Canine parvovirus (CPV) is an extremely contagious virus that causes sudden vomiting and often bloody diarrhoea, mainly in unvaccinated puppies. Without treatment it can quickly become life-threatening, but with intravenous fluids and supportive care started in time, 70–90% of dogs survive. If you suspect parvo, a rapid test on a stool sample gives you a first answer in 5–10 minutes – but a positive result means going to the vet immediately.
In this article we explain what parvo is, the typical symptoms, how it spreads, when and how to test at home, and when you need to rush to the vet.
What is parvovirus and why is it so dangerous?
Canine parvovirus attacks rapidly dividing cells: the intestinal lining and the immune system of puppies. Puppies aged 6–24 weeks are most at risk, but it can also cause severe disease in unvaccinated adult dogs.
The virus is extremely hardy: indoors at room temperature it stays infectious for at least 2 months, and outdoors, protected from sunlight and drying out, for months or possibly years (Merck Veterinary Manual). That is why it can sweep through a kennel, shelter or boarding facility in no time.
What are the symptoms of parvo in dogs?
The disease usually starts with lethargy, loss of appetite and fever, followed within 24–48 hours by vomiting and often bloody diarrhoea (Merck Veterinary Manual). If you notice several of the following, be suspicious straight away:
- severe, often watery or bloody diarrhoea,
- repeated vomiting,
- complete loss of appetite,
- lethargy: no interest in play, hiding away,
- fever or, on the contrary, an abnormally low body temperature,
- rapid decline and weight loss within just 1–2 days,
- signs of dehydration: sunken eyes, sticky gums, skin that does not spring back.
A lively puppy can become critically ill within 24–48 hours. If an unvaccinated puppy suddenly develops diarrhoea and vomiting, treat it as parvo until proven otherwise. Not all vomiting is parvo – we explain when vomiting is harmless here: Dog vomiting: what does the colour mean and when is it an emergency?
What is the incubation period of parvo?
Symptoms usually appear 5–7 days after infection, but can start anywhere between 2 and 14 days. An infected dog sheds the virus from around day 4–5 after infection, throughout the illness and for about 10 days after recovery (Merck Veterinary Manual).
How can your dog catch parvo?
The virus is shed in the faeces of a sick dog and from there gets onto soil, shoe soles, paws, toys and food bowls. That is why "we never go to the dog park" is no guarantee of safety:
- you can carry it into your home on your shoes,
- a visiting animal can bring it in indirectly,
- your puppy may run around a contaminated garden where a sick dog used to be,
- a dog from a shelter, a breeder or with an unknown background may already be infected when it arrives.
A single dog that looks healthy but is infectious is enough to make several animals in a litter or group of puppies ill.
When should you do a parvo rapid test?
- your puppy suddenly develops severe diarrhoea and/or vomiting,
- an unvaccinated dog, rescued from a shelter or the street, becomes ill,
- as a breeder, you want certainty before puppies go to their new homes,
- in a multi-dog household, one dog suddenly becomes very unwell,
- a new dog with diarrhoea arrives at a shelter.
A home test does not replace a veterinary examination, but within 5–10 minutes it shows whether parvovirus antigen is present in the stool. We cover test reliability in detail here: How accurate is a home rapid test?
How does the parvo rapid test work?
Using a fresh stool sample or rectal swab: mix the sample into the dilution buffer, put 3 drops onto the cassette and read the result between 5 and 10 minutes. After 15 minutes the result is invalid.
| What you see | Result | What to do |
|---|---|---|
| Both C and T lines appear | Positive | Parvovirus antigen is present in the stool: see a vet immediately, an emergency vet if necessary. |
| Only the C line appears | Negative | No parvo detected in this sample. If symptoms are severe, still see a vet, because virus shedding can fluctuate. |
| No C line | Invalid | Incorrect sampling or a technical error: repeat with a new cassette. |
Important: after a parvo vaccination with a modified live virus, a false positive result can occur for 4–10 days (Merck Veterinary Manual), so if your dog was recently vaccinated, tell your vet when. According to the manufacturer's validation against PCR on 300 samples, the MancsLab CPV Ag rapid test has a sensitivity of 98.00% and a specificity of 98.67%.
What should you do if the parvo test is positive?
- Go to the vet immediately – out of hours, go to an emergency clinic.
- Do not force your dog to eat or drink; inhaling food or water can be dangerous.
- If you have several dogs, isolate the sick one at once: separate bowls, separate bed.
- Disinfect: diluted household bleach (1:30) and products based on peroxygen, potassium peroxymonosulfate or accelerated hydrogen peroxide are effective against parvo (Merck Veterinary Manual). Not every disinfectant works, so discuss this with your vet too.
The vet helps the dog survive the disease with intravenous fluids, anti-nausea medication, pain relief, antibiotics if needed, and intensive care. There is no drug that kills the virus itself, so early detection literally saves lives.
When should you test again?
- When a new puppy arrives: screen on arrival, then test again if symptoms appear.
- In a multi-dog household: if one dog had parvo, test the others immediately if they show suspicious symptoms.
- Negative test but symptoms not improving: your vet will recommend further tests and possibly a repeat test.
After recovery a dog can still shed the virus for about 10 days, so keep it isolated during this period too; your vet will decide when to do a follow-up check.
How can you prevent parvo?
- Vaccination: in puppies typically at 6–8, 10–12 and 14–16 weeks of age, then a booster one year later (Merck Veterinary Manual). You can find the week-by-week schedule here: Puppy vaccination schedule 2026.
- Until the vaccination series is complete, avoid unknown dogs and high-risk places.
- For dogs rescued from a shelter or the street, isolate and test them during the first few days.
- In multi-dog households, breeding kennels and shelters: regular hygiene, disinfection and screening of new arrivals.
Which test do you need for a puppy with diarrhoea?
If you only want to rule out parvo, the CPV Ag rapid test is enough. For a puppy with diarrhoea the CPV/CCV/Giardia 3-in-1 test is useful, as it checks a single sample for parvo, coronavirus and Giardia. All tests suited to diarrhoea in one place: diarrhoea in dogs and cats.
Frequently asked questions about parvovirus
Can my vaccinated dog get parvo?
Vaccination gives strong protection, but it is not a 100% guarantee: especially in puppyhood, during the vaccination series, there is a window when protection is not yet complete. That is why you should avoid dogs of unknown background and high-risk places during the vaccination programme.
Is a dog with parvo contagious to other dogs?
Yes. Parvovirus is shed in large amounts in the faeces of a sick dog and can still be shed for about 10 days after recovery. The sick dog must be completely isolated, and the environment disinfected with a product that is effective against parvo.
How long does parvovirus survive in the environment?
Indoors for at least 2 months; outdoors, protected from sunlight and drying out, for months or possibly years. That is why, after a case of parvo, you need to be careful for a long time before bringing in unvaccinated puppies.
Can parvo be cured?
There is no drug that kills the virus; treatment consists of intensive intravenous fluid and supportive therapy. With proper care, 70–90% of dogs survive, which is why it is critical to test and see a vet at the first sign of symptoms.
When can I bring home a new puppy if I had a dog with parvo?
This is always an individual decision for your vet. Because the virus stays infectious for months, before an unvaccinated or partly vaccinated puppy arrives, be sure to talk to your vet about disinfection and when the house and garden will be safe.
Summary
Parvo can get worse within hours, especially in unvaccinated puppies. With sudden vomiting and bloody diarrhoea, a home rapid test gives you quick guidance, but a positive result or severe symptoms mean an immediate trip to the vet. The best protection is completing the vaccination series and isolating new dogs.
Sources
- Merck Veterinary Manual: Canine Parvovirus Infection (Parvoviral Enteritis in Dogs). merckvetmanual.com
- Manufacturer's validation data (CPV Ag rapid test). product page
Important: this article provides general information and does not replace veterinary advice. Treatment and follow-up checks must always be decided by a vet. MancsLab rapid tests are intended for preliminary screening at home.