Dog Flu: What Every Owner Needs to Know

Dr. Jacqueline Brister

Canine Influenza

Dog flu, or canine influenza virus, is a highly contagious virus that infects the majority of exposed dogs. The most common strains in the United States are the H3N8 and H3N2 subtypes of the canine influenza A virus. Canine influenza virus can be spread from infectious respiratory fluids of dogs. It is most commonly spread by coughing or sneezing. If you have been around an infected dog, you can carry the virus to your own dogs, because the virus can live for up to 48 hours in the environment.

How Does Influenza Affect Dogs?

When a dog comes into contact with the infectious flu particles, the virus travels to the respiratory tract and begins replicating within the cells lining the airway. The body responds by sending white blood cells to fight the virus. Sometimes these cells, in combination with the virus, can cause inflammation and fluid accumulation in the surrounding tissues. This may lead to airway damage, resulting in rhinitis, bronchitis, or pneumonia. This airway damage may cause dogs to be more susceptible to bacterial infections in the airway, causing further trauma to the respiratory tract.

What Are the Symptoms of Dog Flu?

The symptoms of canine influenza virus vary. Many dogs are able to fight off the infection without showing any major signs of illness. Mild symptoms include cough, runny nose, and a poor appetite. Some dogs will be affected more severely than others. Severely affected dogs may develop life-threatening pneumonia. Symptoms of this include trouble breathing, fever, or being unable to get up and move around. Vomiting and diarrhea are also common symptoms. It is important to note that even if dogs are not showing symptoms, they can still be contagious to others.

Will My Dog Need Treatment?

For pets with only mild symptoms, it is often best to let the virus run its course. Make sure to keep your dog well hydrated by offering plenty of water or adding canned food to his or her meals. Adding additional canned food may also entice your dog to eat since a poor appetite is a common symptom. It is important to keep your pet away from other animals or pets within the household and to wash your hands frequently to prevent the infection from spreading.

For severely-affected dogs, hospitalization with IV fluids, medications to help them breathe, and oxygen supplementation may be necessary. If your veterinarian suspects that a bacterial infection has also occurred, your dog may be prescribed antibiotics as well.

Even after a dog has cleared or fought off the infection, some of his or her symptoms, such as coughing, may continue for several weeks. This is because of the inflammation that developed during the infection. The damage to the airways does not always heal immediately, even after the infection is gone.

How Is Canine Influenza Diagnosed?

Diagnosing canine influenza can be difficult because several tests are needed and the timing will vary between tests. Some tests require blood or saliva and mucus samples at the beginning of the infection, while other tests need to be run later in the course of the disease. The tests may not always be accurate depending on how many viral particles can be found in the blood stream or samples.

If your pet is showing severe symptoms, your veterinarian may also want to check routine blood tests such as a serum chemistry and a complete blood count to determine how your pet’s body is handling the infection. X-rays are commonly performed to determine if pneumonia is present and how severely your pet’s lungs are affected.

Should I Vaccinate My Dog for Canine Influenza?

There are approved vaccines available for dogs against canine influenza. Unfortunately, the vaccines do not prevent your dog from developing infection if he or she is exposed. They will, however, decrease the severity of the infection and symptoms. The vaccines will also decrease the amount of virus he or she can spread to others.

Currently, the vaccines are only recommended for high-risk areas. Canine influenza is most commonly found in the New England states such as New York and New Jersey, as well as areas in the Midwest such as Colorado and Wyoming. Florida may also be considered a state common for the influenza virus to circulate.

Dogs in heavily populated environments within states that commonly experience virus outbreaks may benefit from vaccination. The vaccines require an initial dose followed by a booster 2-4 weeks later and then again once every year. One dose of vaccine alone will not be effective because it takes up to a week after the booster to create adequate protection.

How Else Can I Prevent the Infection?

If there is an outbreak in your area, avoid places that may experience a high population of dogs. Examples of high-population environments include kennels, dog parks, grooming facilities, and pet stores. If you have been around dogs that have been sneezing or coughing, wash your hands and change your clothes before petting and hugging your own pets.

If one of your own dogs is sick, keep him or her isolated from your other pets, including using separate food and water bowls. Wash your hands and change your clothes as needed. Clean any areas the sick dog has been with dilute bleach.

Many dogs remain contagious even after the symptoms have improved, so be sure to isolate your pet for at least 3 weeks after the symptoms started.

Can I or My Other Animals Catch Dog Flu?

So far, no humans have contracted canine influenza. Experts report that the chance of this occurring is highly unlikely. Some cats, however, have become infected with the H3N2 strain of canine influenza but very few developed any signs of illness. Mild cough and runny nose were the most common symptoms seen. While there is no vaccine available for cats, following the same protective and preventive measures as you would for your dogs should help keep your cats safe from any rare chance of infection.

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