What is Canine Parvovirus?

  • By: Mick Whitefield
  • Time to read: 7 min.
Photo 1433162653888 A571Db5Ccccf


Canine Parvovirus is a highly contagious and potentially fatal, fast acting virus generally transmitted between dogs through contact with infected faeces. Primary signs and symptoms are vomiting with diarrhoea, loss of appetite and dehydration leading to lethargy and also a fever. The dogs at greatest risk of mortality are UNVACCINATED dogs such as puppies.


What are the first signs of Parvovirus?

The most prominent signs and symptoms of Parvo are:

  • Vomiting
  • Bloody diarrhoea
  • Loss of appetite 
  • Dehydration
  • Lethargy and collapse
  • Fever
  • Weak or shallow panting

Any dog owner should be aware of the first symptoms related to Parvo since its rapid progression within the body makes it quite time sensitive to get treatment.

These symptoms appear between 3 days to a week from the moment the virus has entered the dog’s body. Following a brief incubation period, it will quickly replicate and spread throughout the body via the bloodstream.

There are no particular characteristics to the vomit, but the stool will most often appear watery, tinted with blood or have a yellow tone mucus, along with a pungent smell. Quickly following this will be a loss of appetite followed by dehydration which will then be accompanied by signs of fatigue and fever.

Watery Poo

Watery Stools rather than completely solid and definitive
signs of Lethargy show signs of illness
Lethargic Dog
Unvaccinated dogs have the greatest risk

Shallow Panting Sick Dog
A dog showing early signs of listlessness with shallow panting

If any such symptoms are observed simultaneously, or in succession, a veterinarian should promptly be consulted to carry out a diagnosis and treatment, if necessary.

Signs of a fever will warn of damage to the dog’s immune system. This is most frequently associated with a drop in the concentration of white blood cells within the blood. The function of these white blood cells is to protect the body against any incoming harmful invaders such as viruses and infectious diseases. Such a drop in white blood cells will therefore leave dogs more susceptible to illnesses.

If the symptoms dissipate around 4 days after they have first appeared, the risk of mortality tends to drop significantly, and a full recovery may lead to increased resistance to the parvovirus in the future.

However, such chances of healing remain very slim without medical intervention, particularly with younger puppies.

How do dogs get parvo?

The main point of entry for the virus is through the dog’s mouth. Since dogs are constantly sniffing around, eating off the ground or cleaning themselves after a walk outside, the exposure is prominent and hardly avoidable.

Unfortunately, this leads straight to the most vulnerable part of the body: the digestive system. It is precisely within the gastric and intestinal tracts that the virus is most destructive as it damages the lining and inhibits its ability to absorb nutrients.

The Parvo virus is highly contagious amongst dogs as any direct or even indirect contact will allow it to be transferred.

As the dog may succumb to severe dehydration or bacterial infection from its weakened immune system. Both fatal examples contribute to the appearance of the aforementioned symptoms in various ways and hence call upon the owner’s vigilance in their detection and potential combinations.

The faeces or vomit of infected dogs may be sniffed by a dog directly, or merely picked up by an owner’s shoes

Dog Eating Poop Small
Dogs will lick many things simply out of curiosity

Part of the problem is that parvovirus is highly resistant to harsh environments and cleaning products and it can survive up to half a year in the grass where you take your dog to your favourite park. Once a place or material has been contaminated, only the use of bleach may help to return it to a dog-safe zone. Hence, even pet shops, Veterinary hospitals or any establishment associated with dogs may themselves be susceptible to contamination.

How to treat Parvovirus?

Treatment for dogs suffering from Parvo will vary depending on the severity of the illness. However, most cases will require a stay in a veterinary clinic to aid the healing process and facilitate rehabilitation.

Professional treatment also ensures that infected dogs are safely isolated to prevent the spread of the disease to other dogs. An early release could place other dogs at greater risk and even decrease the dog’s chances of survival.

For cases of acute dehydration, intravenous drips can be used to replenish the body with all the water and nutrients lost from vomiting and diarrhoea, as well as to allow the digestive tract to recover before allowing the dog to eat and drink on its own.

Antibiotics might be used to fight off any pre-existing infection or to help the immune system recover. Similarly, blood transfusions might be recommended in cases where the parvovirus has infected the bone marrow. This would aim to increase white blood cell concentration in the bloodstream and restore a well-functioning defence system to prevent further infections.

Once Parvo has been successfully treated, the previously infected dog develops a life-long immunity to the virus. However, this should not dissuade owners from remaining aware of any potential symptoms their dog might be experiencing, and more importantly even, of their own role in the spread of Parvo to other dogs.

Can Humans catch Parvo?

The parvovirus, which dogs are susceptible to, cannot be transmitted to humans. It does not tend to spread across different animal species either, although the canine type we are concerned with here appears to have originated from the feline parvovirus most common amidst cats where it is even more aggressive.

Nevertheless, it is also important to note that humans may easily aid the transfer of the virus between other dogs, from the ground by means of their shoes, or from the direct contact of their clothes or hands with an infected dog.

Can my Puppy get Parvo?

Yes. It is recommended for any puppy turning 6 weeks old to get a Parvovirus vaccination. The length of such a cycle is very much determined by the breed of dog as larger breeds may need to keep regular tests and further jabs until they are 6 months old, whereas smaller ones may only need help until they are 4 months of age.

Test For Parvovirus
Testing for Parvovirus

Unvaccinated puppies, or a puppy that has only just received their first injection, does not have any protection against the parvovirus or any other diseases that we vaccinate against. Your puppy will not be safe to go out for a walk or to meet other dogs until 1-2 weeks after they have completed their first vaccination course, in the meantime:

  • At home and in the garden. Your puppy is safe to go into the garden as long as no unvaccinated dogs have frequented recently.
  • Public places. This is not recommended, but if you have to, make sure that you carry them. Do not put them down to sniff around the ground.
  • Puppy classes. As long as your puppy is healthy, you can enrol in a puppy class. The learning benefits will far outweigh the very small risk of catching parvovirus from another puppy at the class.

How to prevent Parvo?

The most effective and common prevention is vaccination. As with humans, the earlier the vaccine is administered, the safer your dog will be.

For any additional information relating to a specific breed of dog, it is always best to refer to a veterinarian who will inform on the best course of action. In any case, parvo shots are amongst the most common vaccines administered so any visit to a clinic should be at the forefront of your vaccination treatments.

No matter the breed, it is in the puppy’s fragile infancy that such action needs to be taken to avoid the most fatal cases of canine parvovirus. Care should also be extended throughout the dog’s life, if necessary as yearly booster shots should become a common habit.

Additionally, if your dog has had Parvo and potentially contaminated your home or other known public areas, it is important to take cautionary measures to prevent any further spread. Using diluted bleach to disinfect homes is highly recommended to eradicate any last trace of the virus indoors and on any bedding (don’t bleach your bedding though, just wash it). 

The History of Parvovirus

The canine parvovirus immediately rose to prominence as a fatal and highly contagious disease which spread across the globe in a matter of months. The epidemic, which ensued from its appearance in 1976, led to widespread gastro-intestinal illnesses in dogs, with the most severe cases observed amidst puppies.

Dog With Intraveneous Drip
Puppy with intravenous drip in a veterinary clinic

Whilst dog owners grieved their pets, it was found that the virus, (most commonly referred to as ‘Parvo’) could also spread to wild canines and even certain wild animals. The surprising reach of the virus allowed it to be identified as a close relative to the feline type. It is known as the feline panleukopenia virus whose mutations led to the establishment of the type 2 canine parvovirus (CPV), which we know to most commonly infect pet dogs.

Although its width barely stretches past a millionth of a millimetre, one may not be fooled by its apparent simplicity as its ability to quickly duplicate and evolve shapes it into the deadly pathogen it is.

Parvovirus Multiplying
Parvovirus B19

Its main target areas in the body are the hotspots of cell division where new cells are constantly being generated to maintain the body’s defensive system, as with white blood cells, or its digestive systems, in the regeneration of the intestinal lining.

Unfortunately, no breed of dogs is spared by the reach of this virus’, but infections are most common amidst puppies, decreasing with age from a 91% mortality rate in puppies to just 10% in adult dogs.


One cannot neglect the danger posed by the parvovirus, dog owners even less so. Hence, any prevention which might help one avoid the heartbreak of losing their faithful companion, or just bypass the sight of their beloved dog suffering needlessly, should be taken.

Sick Looking Dog
Sick Boxer

Vaccination is the quick and inexpensive prevention. It is all you need to protect your dog and other dogs from such a cruel and vicious virus which modern medicine has luckily managed to confront and win.

Nevertheless, it is also the dog owner’s responsibility to make their dogs’ favourite places safe for all by immediately picking up faeces to reduce the risk of contamination and dispersion. 

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