Canine Influenza (Dog Flu)

Kirkwood Animal Hospital would like you to know that by the time Canine Influenza H3N8 arrives in the St. Louis area it may be too late to protect your dog. The protection provided by the vaccine requires 2 doses administered 3 weeks apart. Kirkwood Animal Hospital recommends that you have your pet vaccinated if it has exposure to other dogs outside the home.

To answer any question that you might have about Canine Influenza, we have compiled information for a variety of reliable sources. The articles are posted below along with links to the original publication. You may also feel free to call or visit your to discuss your pet’s needs.

Key Facts about Canine Influenza (Dog Flu)

from the CDC in Atlanta, GA (

Questions & Answers:

What is canine influenza (dog flu)?
Dog flu is a contagious respiratory disease in dogs caused by a specific Type A influenza virus referred to as a “canine influenza virus.” This is a disease of dogs, not of humans.

What is a canine influenza virus?
The “canine influenza virus” is an influenza A H3N8 influenza virus (not a human influenza virus) that was originally an equine (horse) influenza virus. This virus has spread to dogs and can now spread between dogs.

How long has canine influenza been around?
The H3N8 equine influenza virus has been known to exist in horses for more than 40 years. In 2004, however, cases of an unknown respiratory illness in dogs (initially greyhounds) were reported. An investigation showed that this respiratory illness was caused by the equine influenza A H3N8 virus. Scientists believe that this virus jumped species (from horses to dogs) and has now adapted to cause illness in dogs and spread efficiently among dogs. This is now considered a new dog-specific lineage of H3N8. In September of 2005, this virus was identified by experts as “a newly emerging pathogen in the dog population” in the United States.

What are the symptoms of this infection in dogs?
The symptoms of this illness in dogs are cough, runny nose, and fever. However, a small proportion of dogs can develop more severe respiratory disease.

How serious is this infection in dogs?
The number of dogs infected with this disease that die is very small. Some dogs have asymptomatic infections (no symptoms), while some have severe infections. Severe illness is characterized by the onset of pneumonia. Although this is a relatively new cause of disease in dogs and nearly all dogs are susceptible to infection, about 80 percent of dogs will have a mild form of disease.

How does dog flu spread?
Canine influenza virus can be spread by direct contact with respiratory secretions from infected dogs, by contact with contaminated objects, and by people moving between infected and uninfected dogs. Therefore, dog owners whose dogs are coughing or showing other signs of respiratory disease should not participate in activities or bring their dogs to facilities where other dogs can be exposed to the virus. Clothing, equipment, surfaces, and hands should be cleaned and disinfected after exposure to dogs showing signs of respiratory disease.

Is there a test for canine influenza?
Testing to confirm canine influenza virus infection is available at veterinary diagnostic centers. The tests can be performed using respiratory secretions collected at the time of disease onset or using two blood samples; the first collected while the animal is sick and the second 2 to 3 weeks later.

How is canine influenza treated?
Treatment largely consists of supportive care. This helps the dog mount an immune response. In the milder form of the disease, this care may include medication to make your dog more comfortable and fluids to ensure that your dog remains well-hydrated. Broad spectrum antibiotics may be prescribed by your veterinarian if a secondary bacterial infection is suspected.

Is there a vaccine for canine influenza?
Yes, an approved vaccine is available.

What is the risk to humans from this virus?
To date, there is no evidence of transmission of canine influenza virus from dogs to people and there has not been a single reported case of human infection with the canine influenza virus. While this virus infects dogs and spreads between dogs, there is no evidence that this virus infects humans.

However, human infections with new influenza viruses (against which the human population has little immunity) would be concerning if they occurred. Influenza viruses are constantly changing and it is possible for a virus to change so that it could infect humans and spread easily between humans. Such a virus could represent a pandemic influenza threat. For this reason, CDC and its partners are monitoring the H3N8 influenza virus (as well as other animal influenza viruses) along with instances of possible human exposure to these viruses very closely. In general, however, canine influenza viruses are considered to pose a low threat to humans. As mentioned earlier, while these viruses are well established in horse and dog populations, there is no evidence of infection among humans with this virus.

My dog has a cough what should I do?
Schedule an appointment with your veterinarian so that they can evaluate your dog and recommend an appropriate course of treatment.

Where can I find more information on canine influenza virus?
More information on canine influenza in pet dogs can be found in this article: Influenza A Virus (H3N8) in Dogs with Respiratory Disease, Florida in Emerging Infectious Diseases journal.

Related Links
The following websites may provide additional information about particular animal diseases or conditions, or infection control practices:
CDC Healthy Pets Healthy People
American Veterinary Medical Association
Association of Shelter Veterinarians

10 Things to Know About the H3N8 Dog Flu

University of Florida College of Veterinary Medicine

By Cynda Crawford, D.V.M., Ph.D.

Micah Albert for The New York Times Who’s at risk from canine influenza?
Dr. Cynda Crawford, clinical assistant professor in the Maddie’s Shelter Medicine Program at the University of Florida College of Veterinary Medicine in Gainesville, recently answered dozens of readers’ questions on the Consults blog, “The Dog Flu Virus: Are You or Your Pet At Risk?” Many readers had questions about flu symptoms, how the virus is spread and whether their pets should receive the newly approved vaccine for the disease. Here are 10 things Dr. Crawford believes everyone should know about canine influenza and the risks to pets and people.

What is canine influenza?
Canine influenza is a highly contagious respiratory infection of dogs caused by a novel influenza virus that was first discovered in 2004. We do not use the general term “dog flu” because it could refer to any flu-like illness in dogs due to various causes. Rather, canine influenza is a specific disease caused by a particular subtype, H3N8, of the influenza A virus.

Where does canine influenza occur?
Canine influenza has been documented in 30 states and the District of Columbia. At this time, the canine influenza virus is very prevalent in many communities in Colorado, Florida, New York and Pennsylvania. There is no evidence that canine influenza H3N8 is currently infecting dogs in other countries.

What type of infection does canine influenza virus cause?
Like influenza viruses that infect other mammals, canine influenza virus causes an acute respiratory infection in dogs. It is one of several viruses and bacteria that are associated with canine infectious respiratory disease, or what’s commonly referred to as “kennel cough.” The canine influenza virus can cause respiratory disease by itself or along with other canine respiratory pathogens.

Unlike human influenza, canine influenza is not a “seasonal” infection. Infections can occur year round.

What are the symptoms and clinical signs of canine influenza?
Like influenza viruses in other species, canine influenza virus causes a flu-like illness consisting of cough, sneezing and nasal discharge (”runny nose”). Fever can also occur, but it is usually transient and rarely noticed by pet owners. There are no clinical signs that distinguish canine influenza from other respiratory infections. That is why diagnostic tests must be performed to determine the cause of respiratory infections in dogs (see below).

Virtually all dogs exposed to the canine influenza virus become infected; about 80 percent develop a flu-like illness, while another 20 percent do not become ill. Fortunately, most dogs recover within two weeks without any further health complications. However, some dogs progress to pneumonia, which is usually due to secondary bacterial infections.

While the death rate for canine influenza is very low, the secondary pneumonia can be life-threatening in some cases. There is no evidence that dogs of particular age or breed are more susceptible to developing pneumonia from canine influenza.

Who is susceptible to canine influenza?
Because canine influenza is due to a virus that is novel to the canine population, dogs lack preexisting immunity to the virus. Dogs of any breed, age or vaccination status are therefore susceptible to infection. It is likely that dogs that have recovered from infection retain immunity to re-infection for an undetermined time period, although studies have not verified for how long.

Canine influenza is most likely to spread in facilities where dogs are housed together and where there is a high turnover of dogs in and out of the facility. Dogs in shelters, boarding and training facilities, day care centers, veterinary clinics, pet stores and grooming parlors are at highest risk for exposure to the virus, especially if these facilities are located in communities where the virus is prevalent. Dogs that mostly stay at home and walk around the neighborhood are at low risk.

Canine influenza virus does not infect people, and there is no documentation that cats have become infected by exposure to dogs with canine influenza. Nor is there any evidence that the canine virus can infect birds.

How is canine influenza transmitted?
As with other respiratory pathogens, the most efficient transmission occurs by direct contact with infected dogs and by aerosols generated by coughing and sneezing. The virus can also contaminate kennel surfaces, food and water bowls, collars and leashes, and the hands and clothing of people who handle infected dogs. Fortunately, the virus is easily inactivated by washing hands, clothes and other items with soap and water.

How is canine influenza treated?
Since canine influenza is a viral infection, treatment consists mainly of supportive care while the virus runs its course, much like for human influenza. Dog owners should consult with their veterinarians if they think their dog has canine influenza. The veterinarian can determine what type of supportive care is needed, including whether antibiotics should be given for secondary bacterial infections. Dogs with pneumonia most likely require more intensive care provided in a hospital setting under the supervision of a veterinarian.

Is canine influenza contagious?
Like influenza infections in other species, canine influenza is highly contagious. Infected dogs shed virus in their respiratory secretions for 7 to 10 days, during which time the dog is contagious to other dogs. Infected dogs that do not show clinical signs are also contagious.

Once the virus has run its course, the dog is no longer contagious. Therefore, we recommend that dogs with canine influenza be isolated from other dogs for two weeks to err on the conservative side. The canine influenze virus does not cause a permanent infection.

How is canine influenza diagnosed?
Canine influenza cannot be diagnosed by clinical signs because all of the other respiratory pathogens cause similar signs of coughing, sneezing and nasal discharge. For dogs that have been ill for less than four days, veterinarians can collect swabs from the nose or throat and submit them to a diagnostic laboratory that offers a validated PCR test for canine influenza virus. The most accurate test recommended for confirmation of infection requires the collection of a small blood sample from the dog during the first week of illness, followed by collection of another sample 10 to 14 days later. The paired serum samples are submitted to a diagnostic laboratory for measurement of antibodies to CIV that were formed in response to infection.

Is there a vaccine for canine influenza?
In May 2009, the United States Department of Agriculture approved for licensure the first influenza vaccine for dogs. The vaccine was developed by Intervet/Schering Plough Animal Health Corporation.

The canine influenza vaccine contains inactivated whole virus, so there is no chance that the vaccine itself can cause respiratory infections. During tests to evaluate vaccine performance, there were no side effects or safety issues in a field trial that included more than 700 dogs ranging in age from six weeks to 10 years and representing 30 breeds.

The vaccine is intended as an aid in the control of disease associated with C.I.V. infection. Although the vaccine may not prevent infection, efficacy trials have shown that vaccination significantly reduces the severity and duration of clinical illness, including the incidence and severity of damage to the lungs. In addition, the vaccine reduces the amount of virus shed and shortens the shedding interval. This means that vaccinated dogs that become infected are less likely to have severe symptoms and are not as contagious to other dogs. These benefits are similar to those provided by influenza vaccines used in other species, including people.

The canine influenza vaccine is a “lifestyle” vaccine in that it is intended for dogs at risk for exposure to C.I.V., including those that participate in activities with many other dogs or those housed in communal facilities, particularly in communities where the virus is prevalent. Dogs that may benefit from canine influenza vaccination include those that are already receiving the kennel cough vaccine for Bordetella because the risk groups are the same.

Dog owners should consult with their veterinarian to determine whether their dog’s lifestyle includes risk for exposure to C.I.V., and the protection provided by the canine influenza vaccine. The vaccine is not yet available in veterinarians’ offices, and the price has not yet been set.

From the Manufactures of the Vaccine:
Vaccine Against Canine Flu Granted Conditional License by USDA
23 June 2009

ROSELAND, N.J., June 23, 2009 – Intervet/Schering-Plough Animal Health, the global leader in veterinary biologicals, today announced the availability of the first vaccine against canine influenza virus (CIV), which was granted a conditional product license by the U.S. Department of Agriculture (USDA) on May 27, 2009, for use by veterinarians in the United States. (

“Canine influenza is a highly contagious respiratory infection that has a significant impact on dogs housed in shelters, kennels and communal facilities,” said Cynda Crawford, D.V.M., Ph.D., University of Florida, Clinical Assistant Professor of Shelter Medicine. “The availability of a vaccine can help prevent the medical, financial and emotional costs associated with this new virus.”

Canine influenza was first identified in the United States in 2004. Since then, CIV has continued to spread and has now been detected in dogs in 30 states and the District of Columbia, according to Dr. Crawford and Edward J. Dubovi, Ph.D., Professor of Virology, Cornell University College of Veterinary Medicine, two of the nation’s leading experts on Canine H3N8 who have been tracking the disease since 2004.

Most dogs have no immunity to canine influenza because it is a novel pathogen and, therefore, the infection can spread quickly through animal shelters, adoption groups, pet stores, boarding kennels, veterinary clinics and any location where dogs congregate. According to the U.S. Centers for Disease Control and Prevention (CDC), there is no evidence of transmission of the virus from dogs to people.

According to Terri Wasmoen, Ph.D., an immunologist and senior director of Biological Research for Intervet/Schering-Plough Animal Health, dog owners might not realize their pets are sick enough to need medical care until the dogs begin coughing, which occurs several days or more after the dog contracts CIV. The onset of coughing is a sign that the dog is vulnerable to pneumonia. “Preventing a viral infection that can make dogs susceptible to a complex of canine respiratory pathogens, commonly known as kennel cough syndrome, further strengthens the case for vaccination,” she said.

In 2006, the American Veterinary Medical Association (AVMA) called for the development of a vaccine against the spread of the disease, stating “there is urgent need for an effective canine influenza vaccine to improve the health and welfare of animals and reduce the financial impacts of canine influenza.”

Christopher Pappas, Jr., D.V.M., Director, Companion Animal Technical Services, Intervet/Schering-Plough Animal Health, said, “We developed the vaccine in response to the growing problem of the disease. We are pleased that our expertise in respiratory disease and vaccines can help prevent costly outbreaks and keep dogs healthier.”

Canine Influenza Vaccine, H3N8 has been demonstrated to reduce the incidence and severity of lung lesions, as well as the duration of coughing and viral shedding. The vaccine, made from inactivated virus, is intended as an aid in the control of disease associated with canine influenza virus infection, a type A, subtype H3N8. It is administered by subcutaneous injection in two doses, two to four weeks apart. It may be given to dogs six weeks of age or older and can be given annually as a component of existing respiratory disease vaccine protocols to ensure more comprehensive protection.

On May 27, 2009, the vaccine was granted a conditional license by the USDA’s Animal and Plant Health Inspection Service, which, through its Center for Veterinary Biologics (CVB), evaluates data supporting product purity, product safety under normal conditions of use in field safety trials and demonstration that the product has a reasonable expectation of efficacy. During the conditional license period, Intervet/Schering-Plough Animal Health will continue to submit data obtained in support of the product’s performance, which will be evaluated by government regulators to determine whether a regular product license may be issued.

This press release contains information on a veterinary product based on national registration dossiers and may refer to a product that is either not available in your country or are marketed under a different tradename. In addition, the safety and efficacy data for a specific product may be different depending on local regulations. For more information contact your local Intervet/Schering-Plough Animal Health representative.

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