Dog Viruses – List, Risks, Existing Treatments, Contagiousness & FAQs

Dog Viruses – List, Risks, Existing Treatments, Contagiousness & FAQs

As a doting pet parent, you already know when your dog is feeling under the weather. However, the symptoms of dog viruses are highly variable as well as sometimes life-threatening. Today, we’ll take a look at some of the most common dog viruses, as well as the symptoms and causes of them.

Viruses in dogs range from mild and self-resolving, to severe and fatal without treatment. Because the balance is so uncertain, it is important to get your pooch to the vet if they show signs of illness. The earlier the treatment, the better your pup’s chances of pulling through. So, ready to learn more about viruses in dogs? Read on with us!

What are Viral Diseases or Dog Viruses

In order to cover dog viruses, we must first discuss what exactly a virus is. In short, a virus is an infectious agent, or germ, that replicates inside the living cells of a living being. A virus can infect anything, from animals to plants to bacteria. When a virus gets inside a cell, the cell is forced to produce thousands of copies of the virus. Viruses are extremely adaptable and can avoid detection by the body’s immune system for some time. So, what does the immune system do to combat this?

A special cell in the immune system known as the T-cell circulates in the body, looking for infections. When a cell detects a peptide made by a virus, it begins to kill the infected cell. Similarly, another cell known as the natural killer cell (NK) detects cells that display fewer histocompatibility complex proteins on the cell’s surface. Like the T cell, the NK cell releases toxic substances to kill the infected cell. If the body detects a virus before it can infect any cells, antibodies can bind to them, neutralize them, and then engulf and destroy them. These responses are what vaccines attempt to trigger – by letting the body fight an inactive form of the bacteria or virus, your dog’s white blood cells are better equipped to deal with the infection in the future.

Bacterial vs Viral

While both viruses and bacteria cause disease, there are several key differences between the two. First and foremost, bacteria are living organisms, while the “living” status of viruses is still debated, partly because viruses only grow and reproduce with the help of the host cells that they infect. When outside of a living cell, a virus lays dormant until it eventually hijacks the biochemical activities of living cells. A bacterium, on the other hand, generates its own energy, makes its own food, moves, and reproduces. Next, there are size differences between viruses and bacteria. While the smallest bacteria are about 0.4 microns, viruses range from 0.02 to 0.25 microns. Both are submicroscopic. And, lastly, viruses can infect bacteria, but bacteria cannot infect viruses. To be specific, bacteria are not immune to bacteriophages. These are viruses that specifically infect bacteria.

  • Bacteria are living organisms, viruses are not
  • Viruses only grow and reproduce with a host, bacteria are typically self-sufficient
  • Viruses can be much smaller than bacteria
  • Viral infections are typically systematic, bacterial infections can be local

Common Dog Viruses

There are many viruses that your dog can get, ranging from canine parvovirus to rabies. Knowing the symptoms of each virus and where it comes from could not only give you peace of mind but could save your furry friend, too. While all of these viruses are present in the USA, there are few statistics to suggest how common each virus is.

Canine Parvovirus

Canine parvovirus (CPV-2) is a highly contagious virus of dogs. Spread through both direct and indirect contact, canine parvovirus is transmissible through infected feces, toys, soil, and shoes. Unfortunately, the virus is very hardy and can survive in feces-contaminated earth for 5 months or more. Because it’s so easily transmissible, the virus is most common in animal shelters, kennels, and pet stores.

The early symptoms of systemic canine parvovirus include depression, loss of appetite, vomiting, severe diarrhea, and high fever. In severe cases, bloody diarrhea occurs. With the nature of these symptoms, rapid dehydration can quickly pose a grave threat to infected dogs, with some dying within 3 to 5 days of infection. Young puppies are most at risk with CPV-2, often dying of shock as early as 2 days after infection. The second form of CPV-2 infection causes severe myocarditis. Myocarditis affects puppies under 3 months old the most. Within a litter, up to 70% of puppies die from heart failure, while the remaining 30% may die months or years later. The infection causes abdominal swelling, a weak pulse, breathing difficulties, and cold extremities.

Vaccination is the best way to prevent CPV-2. Your puppy should receive vaccinations starting from 7 to 8 weeks old, with a booster every 3-4 weeks until they are 16 weeks old. Surfaces that may host CPV-2 should be washed using bleach at a 1:10 ratio. If your dog recovers from parvovirus, they may stay contagious for up to three to six weeks. During this time, it’s important to keep your pup in quarantine.

parvo virus in dogs
As fatal as the virus can be, it can be cured with the help of professional veterinarians.

Dog Flu

Influenza A virus causes influenza in dogs as well as birds, pigs, horses, bats, and humans. There are several subtypes of the influenza A virus, some of which are more infectious to one species but not to others. This brings us to two important subtypes: H3N8 and H3N2. These two subtypes are usually spread through respiratory tract secretions, meaning that a coughing dog can release the virus into the air. The virus may also be spread via direct contact, or indirectly by a human’s hands or clothing. Unlike some other viruses, these viruses are easily killed by cold, heat, and disinfectants. However, they remain viable on surfaces for up to 48 hours and on human hands for 12 hours.

An outbreak of the H3N8 subtype in racing greyhounds gives caused dogs to display a cough for 10 to 21 days, a runny nose, and a low-grade fever. This subtype has an incubation period of 1 to 5 days. Similar to H3N8 infections, H3N2 infections cause coughing and low-grade fever. For both viruses, it’s noted that the most severe infections and sudden deaths occur due to mixed infections by other viruses or bacteria. And, for both viruses, the cough may closely resemble the type of cough that kennel cough can cause.

Because H3N8 and H3N2 are easily killable, prevention is often simple. In veterinary, shelter, and boarding facilities, a cleaning and disinfection protocol should be in use to reduce the risk of transmission. This might involve disinfecting cages, bowls, exam rooms, and floors. There are also vaccines available for both subtypes that can help to reduce the risk of infection.

Kennel Cough

Kennel cough is a broad term to describe an illness that causes a lot of coughing in your dog. There are multiple agents that can cause kennel cough in dogs. The most common is Bordetella bronchiseptica, a bacteria. The viruses responsible include canine parainfluenza virus, canine adenovirus type-2, and canine respiratory coronavirus. Each of these infections is highly contagious. Dogs can transmit the illness through contact with each other and sharing items like water bowls. Overcrowding is a major risk factor for kennel cough in dogs.

The precise symptoms vary depending on the specific virus infecting your dog. Firstly, canine parainfluenza causes a dry cough, tonsilitis, and nasal discharge. With type-2 adenovirus, dogs develop lethargy, fever, and a dry cough persisting for 10 to 15 days. Canine respiratory coronavirus causes coughing, sneezing, and nasal discharge, but many dogs show no signs of the disease. The most severe cases occur when your dog also suffers from co-infections of bacteria like Streptococcus, as they may infect your dog opportunistically. Most dogs recover from kennel cough within a few weeks.

The best prevention is vaccination. There are three forms of kennel cough vaccine: an injection, a nasal mist, and an oral one. Although these vaccines might help, they don’t guarantee that your dog won’t get kennel cough. This is because so many viruses and bacteria can cause the disease. The canine respiratory coronavirus vaccine, for example, is not currently available. You can also regularly clean your dog’s toys and bowls after being around other dogs to reduce the risks.


Rabies is a viral disease that causes progressive inflammation of the brain. The most common virus responsible for rabies is Rabies lyssavirus. Unfortunately, dogs are a common carrier of rabies in several countries, where they transmit rabies to humans and other animals through biting. The virus is present in the saliva of a symptomatic rabid dog, so the route of infection is usually by a bite or scratch. Rabid dogs can infect other dogs as well as humans, making it highly contagious and dangerous.

There are two main types of rabies: furious, and paralytic (dumb). In furious rabies, a dog becomes aggressive, highly excitable, and appears to have a voracious appetite. They may try to chew and eat stones and other unusual objects. Then, paralysis sets in, and the dog may be unable to eat or drink. Seizures are common in this type. In contrast, dumb rabies is more common and involves progressive paralysis. A dog with dumb rabies have difficulty swallowing, act as if they have something stuck in their throat, and be unable to move their face or limbs.

The cornerstone of rabies prevention is vaccination. Rabies vaccines for dogs are safe and effective, as well as a legal requirement in most states. This is important because there is no treatment for a dog with rabies. As such, a dog with rabies will be kept in isolation so that they cannot infect other dogs or people. If after 10 days the dog is healthy, rabies is an unlikely cause for their symptoms.


Canine distemper is a viral disease in dogs, coyotes, foxes, wolves, raccoons, and several other animals. The virus responsible is Canine morbillivirus. Dogs and puppies get the virus from airborne exposure, sharing food and water, and sharing toys. This devastating disease is often fatal. 50% of dogs and 80% of puppies do not survive canine distemper.

In dogs, canine distemper manifests in several different ways. Your dog might show no signs of disease. Other dogs might develop mild respiratory illness, indistinguishable from kennel cough. The most unfortunate dogs develop severe pneumonia, with bloody diarrhea and vomiting. In general, the most common symptoms include a runny nose, salivation, coughing, loss of appetite, and weight loss. When the nervous system comes under attack, muscle twitches, circling, seizures, and incontinence begin. Your dog might be sensitive to light, pain, and touch. Those who survive distemper often develop life-long problems including hard pad disease, tooth enamel damage, deterioration of mental abilities, and incoordination.

There are a number of vaccines against distemper in dogs. To prevent the disease, puppies should begin vaccination at 7 to 8 weeks old, receiving booster shots every 2 to 4 weeks until they reach 16 weeks of age. It’s extremely important that your puppy gets all of these vaccines! Without all of them, the vaccine is overall not effective. As well as vaccination, you can help to prevent distemper through regular cleaning. The virus is killable using disinfectants, and it does not live for more than a few hours in the environment.

Other Examples of Dog Viruses

To list every dog virus would be impossible, as new diseases surface often across the world. It’s not uncommon for viruses to mutate, spilling over from one species to another. This was the case for the H3N8 virus, which spread from horses to dogs in 2004. Overall, though, there are several more viruses that can infect dogs, though these are less commonly seen than the others on our list.

virus spreading dogs
Dogs with diseases are isolated from other dogs to avoid spreading diseases.

Dog Viruses – FAQs

Have any more questions about dog viruses? Feel free to check our Frequently Asked Questions section for more details. If at all in doubt about your pup’s health, always call your vet for advice. Dog viruses can be dangerous for your pup, so be sure to get them treatment as quickly as possible.

Can dog viruses affect humans also?

Some dog viruses can infect humans. These viruses are known as zoonotic viruses. Norovirus and rabies virus are examples of zoonoses that can pass from dogs to humans. There are many more examples of bacterial infections, including Brucella, Salmonella, Bordetella bronchiseptica, Leptospira, and Staphylococcus intermedius.

In contrast to zoonoses, reverse zoonoses are diseases that you can give to your dog. Perhaps one of the most recent reverse zoonoses to hit the news was COVID-19. Although COVID-19 is very unlikely to cause illness in your pets, research shows that the virus can pass from humans to dogs. Similarly, the pH1N1 influenza virus may be transmissible from people and dogs.

When should I take my dog to the vet if he is infected?

You must take your pet to the vet at the first sign of a viral infection. Once your dog contracts a viral infection, they pose a risk to other dogs, especially those who are very young, very old, or unvaccinated. They also become at risk of secondary bacterial infections, which can cause life-threatening sepsis. By getting your pup to the vet as soon as possible, the risk of a secondary infection is minimized, and your pooch can get the fluids and rest they need to get better fast.

If your dog shows signs of rabies or distemper, consider it an emergency and call your vet right away. Unfortunately, rabies is almost always fatal for dogs, and they pose a grave risk to other animals and people once infected. If you suspect that your pet has been exposed to rabies, always call your vet right away. if it is safe to do so, cage your dog and take them to your vet to be quarantined. If 10 days pass and your dog’s symptoms subside, it’s highly likely that rabies was not the cause of their illness. This is because rabies kills within 10 days, usually much sooner. Likewise, canine distemper’s 50% mortality rate for adult dogs makes it highly dangerous. If your dog shows signs of canine distemper, call your vet immediately. Your dog must be separated from other dogs to minimize the risk of transmission to other pets.

What is the deadliest dog virus?

The deadliest dog virus in the world is rabies. Despite advances in veterinary medicine, there is no cure for rabies, and almost all dogs will die after infection. The vast majority of dogs with rabies die within 10 days of showing symptoms, sometimes as soon as 3 to 5 days. This is because the rabies virus causes irreversible, severe inflammation to the brain and spinal cord. Similarly, without treatment, the mortality rate of canine parvovirus exceeds 90%. Tragically, young puppies can die within 48 hours without treatment. This is because parvovirus destroys intestinal tissues, leaving them unable to absorb nutrients. Lastly, canine distemper is especially fatal for puppies, killing 80% of those that it infects. The morbidity rate for adult dogs is 50%. Canine distemper causes severe illness, attacking multiple body systems and causing widespread infection.

Can viruses kill my dog?

Without treatment, any viral illness can technically kill your dog. This is true even for mild cases of canine influenza, as secondary infections from opportunistic bacteria can cause life-threatening sepsis. However, not all cases of viral diseases are life-threatening for dogs. In fact, several viruses tend to cause mild, self-resolving illnesses more often than they cause dangerous complications. For example, canine influenza (H3N8) tends to cause mild, self-limiting symptoms more often than it does severe illness. With that being said, it’s always best to talk to your vet if your pet seems unwell to prevent a tragedy. Your vet may prescribe antibiotics to tackle any bacterial infection that your dog might get along with their viral infection.

Can dogs get COVID-19?

According to the Centers for Disease Control and Prevention, a small number of dogs worldwide have been infected with COVID-19. These cases have occurred after a dog has been in close contact with an infected human. However, most dogs do not show signs of illness. If your dog tests positive for COVID-19, be sure to isolate them from your other pets. Do not use any chemical disinfectants, alcohol, or surface cleaners on your pet. Do not try to put a mask on your pet. There is no reason to abandon a pet that tests positive for COVID-19. There is also no evidence to suggest that dogs can transmit COVID-19 to humans. However, given the rapidly changing situation, please be sure to check the latest government advice and continually assess your own situation!

As always, prevention is better than treatment when it comes to dog viruses. Be sure to keep your pooch up-to-date on their vaccines, including any booster shots they might need! And, keep ensuring that your dog’s environment is clean to prevent infection. Some viruses don’t last long in the environment or are easily killable with disinfectants.