Parvovirus in Dogs: Signs, Treatment and Prevention

At a glance

What it is	A serious viral infection that damages the lining of the gut and weakens the immune system
Who's at risk	Puppies and unvaccinated or incompletely vaccinated dogs above all, though any dog can be affected
Main signs	Severe vomiting, diarrhoea that is often bloody and foul-smelling, lethargy, not eating
Contagious?	Yes, extremely — and the virus can survive in the environment for a long time
Can it be prevented?	Yes, vaccination is the key protection; ask your vet about the right course for your dog

What it is

Canine parvovirus, often just called "parvo", is a virus that targets cells in the body that divide quickly. In dogs, that mainly means the lining of the intestines and the bone marrow, which makes the white blood cells that fight infection.

When the gut lining is damaged, a dog cannot absorb food and water properly, and fluid and blood leak into the intestines. This leads to severe vomiting and diarrhoea, which in turn causes rapid dehydration. At the same time, the damage to the immune system leaves the dog less able to fight off bacteria, which can escape from the damaged gut into the bloodstream. Together, these effects make parvovirus a life-threatening illness. Very young puppies can also, rarely, suffer damage to the heart.

The virus spreads mainly through contact with the faeces of an infected dog. A dog only needs to sniff or lick a contaminated area, or pick up the virus from shoes, hands, bowls, leads, bedding or the ground. Infected dogs shed huge amounts of virus, and they can start shedding before they look ill.

What makes parvovirus particularly worrying is how hardy it is. It can survive for months in the environment, indoors and out, and it resists many everyday cleaning products. That means a puppy can catch it without ever meeting a sick dog — simply by walking where an infected dog has been.

Signs to watch for

Signs usually appear a few days to around a week after a dog has been exposed. They often come on quickly and can worsen within hours. Look out for:

• Sudden, severe vomiting
• Diarrhoea, often bloody, very watery and with a strong, unpleasant smell
• Lethargy, weakness or seeming very flat
• Refusing food
• Signs of belly pain, such as a hunched posture or not wanting to be touched
• Fever, or in severe cases a low body temperature and cold paws
• Signs of dehydration, such as dry or tacky gums, sunken eyes or skin that is slow to settle back when gently lifted

Early on, a puppy may simply seem quieter than usual and turn down a meal. Because things can change so fast, it is wise not to wait and see with a young or unvaccinated dog who suddenly seems unwell.

Many other problems can cause vomiting and diarrhoea, from eating something unsuitable to other infections or poisoning. You can use the symptom checker and our guide on when vomiting needs a vet to understand what you are seeing, but with these signs, a vet should always be involved.

When to see a vet

Act now. Parvovirus is an emergency. If your dog — especially a puppy or a dog who is not fully vaccinated — has severe or repeated vomiting, bloody diarrhoea, or is suddenly weak, lethargic or not eating, phone your vet immediately. If your practice is closed, contact your nearest emergency vet.

Do not wait overnight to see if things improve, and do not try to treat this at home. Dogs with parvovirus can become dangerously dehydrated very quickly, and early treatment gives them the best chance.

When you phone, tell the practice that you are worried about parvovirus. They may ask you to wait outside or come in through a separate entrance, so that other dogs in the clinic are protected. Bring your dog's vaccination record if you can find it quickly, but don't delay to look for it.

How vets diagnose it

Your vet will ask about your dog's age, vaccination history, recent contact with other dogs and how quickly the signs developed. They will then examine your dog, checking hydration, temperature, heart rate and how tender the belly is.

Parvovirus can often be confirmed with a quick test on a sample of faeces, which many practices can run in the clinic. These tests are useful, but they are not perfect, so your vet may still treat your dog as a suspected case if the picture strongly fits.

Blood tests are very helpful. They show how dehydrated your dog is, whether their white blood cell count has dropped, and how their body chemistry and organs are coping. Your vet may also suggest scans or X-rays to check for complications, such as a blockage or one part of the bowel folding into another, which can occasionally happen.

Treatment and management

There is no medicine that kills the parvovirus itself. Instead, treatment supports the body while the dog's own immune system fights the virus off. This is called supportive care, and it usually means hospital treatment, often in an isolation ward.

Depending on how unwell your dog is, care may include:

• Fluids through a drip to correct dehydration and replace lost salts and sugars
• Medicines to control vomiting and nausea, and to ease pain
• Antibiotics to help protect against bacterial infection while the immune system is weak
• Nutritional support, sometimes through a feeding tube, as early feeding can help the gut recover
• Close monitoring of temperature, blood results and hydration, sometimes around the clock
• In severe cases, more intensive treatments such as blood or plasma transfusions

Hospital stays can last several days. Your vet will talk with you about your dog's progress, the likely outlook and the costs involved. Sadly, not every dog survives, even with excellent care, but many dogs who receive prompt, intensive treatment do recover. If full hospital care isn't possible for you, talk openly with your vet — they may be able to discuss other options, though these generally carry more risk.

Prevention

Vaccination is the most important way to protect your dog. Parvovirus vaccines are part of the core vaccines that vets recommend for dogs, and they are very effective. Puppies need a course of vaccinations, and adult dogs need boosters to keep their protection up. The right timing depends on your dog's age, history and circumstances, so ask your vet to set out a plan for your dog rather than relying on a general schedule.

Until your vet confirms that your puppy's vaccination course is complete and they are protected, take extra care:

• Avoid walking your puppy in public places where many dogs go, such as parks and pavements.
• Only let them mix with healthy, fully vaccinated dogs in clean, private spaces.
• Carry them rather than putting them down in vet waiting rooms and other busy areas, unless the practice advises otherwise.
• Ask your vet about safe ways to socialise your puppy during this period, as early socialising matters too.

If you are bringing home a new puppy, ask the breeder or rescue centre about the vaccinations they have already had and bring any records to your first vet appointment.

Recovery and aftercare

Dogs recovering from parvovirus need a gentle return to normal life. Your vet will advise on a bland, easily digested diet and how gradually to reintroduce normal food. Expect your dog to be tired for a while, and keep up with any medicines and check-ups your vet arranges.

Recovered dogs can continue to shed the virus for some time, so keep them away from other dogs, particularly puppies and unvaccinated dogs, until your vet says it is safe.

Isolate and disinfect. Because the virus is so long-lasting, cleaning up properly matters:

• Pick up and dispose of faeces promptly and carefully.
• Ask your vet which disinfectants work against parvovirus, as many standard household cleaners do not. Follow the product's instructions and keep pets away from areas while they are being cleaned.
• Wash bedding, towels and soft toys on a hot wash, and throw away items that cannot be cleaned well.
• Clean bowls, crates, leads and hard surfaces thoroughly, and wash your hands and change clothes after handling a sick dog.
• Remember that gardens and outdoor areas can't be fully disinfected. Talk to your vet before bringing a new puppy or unvaccinated dog into a home or garden where parvovirus has been.

Let anyone whose dog may have been in contact with yours know, so they can check their own dog's vaccinations. With quick action, good nursing and careful cleaning, you can give your dog the best chance and protect others too.