Questions, Answers, and Interim Guidelines
Updated April 12, 2015
Q: What is canine influenza?
A: Canine influenza (CI), or dog flu, is a highly contagious respiratory infection of dogs that is caused by an influenza A virus. The canine influenza virus (CIV) is closely related to the virus that causes equine influenza and it is thought that the equine influenza virus mutated to produce the canine influenza virus. In the U.S., canine influenza has been caused by the H3N8 influenza A virus. A separate canine influenza virus, H3N2, had been reported in Korea, China and Thailand, but not in the U.S. until 2015, when an outbreak in Chicago, IL was determined to be caused by the H3N2 strain.
Two clinical syndromes have been seen in dogs infected with the canine influenza virus—a mild form of the disease and a more severe form that is accompanied by pneumonia.
- mild form — Dogs suffering with the mild form of canine influenza develop a soft, moist cough that persists for 10 to 30 days. They may also be lethargic and have a reduced appetite and fever. Sneezing and discharge from the eyes and/or nose may also be observed. Some dogs have a dry cough similar to the traditional "kennel cough" caused by Bordetella bronchiseptica/parainfluenza virus complex. Dogs with the mild form of influenza may also have a thick nasal discharge, which is usually caused by a secondary bacterial infection.
- severe form — Dogs with the severe form of canine influenza develop high fevers (104ºF to 106ºF) and have clinical signs of pneumonia, such as increased respiratory rates and effort. Pneumonia may be due to a secondary bacterial infection.
Because this is still an emerging disease, almost all dogs, regardless of breed or age, are susceptible to infection and have no immunity. Virtually all dogs that are exposed to the virus become infected and nearly 80% show clinical signs of disease. Fortunately, most affected dogs have the mild form.
Q: Do dogs die from canine influenza?A: Fatal cases of pneumonia resulting from infection with canine influenza virus have been reported in dogs, but the fatality rate is low (less than 10%). Most dogs with CI recover in 2-3 weeks.
Q: How widespread is the disease?
A: The first recognized outbreak of canine influenza in the world is believed to have occurred in racing greyhounds in January 2004 at a track in Florida. From June to August of 2004, outbreaks of respiratory disease were reported at 14 tracks in 6 states (Alabama, Arkansas, Florida, Kansas, Texas, and West Virginia). Between January and May of 2005, outbreaks occurred at 20 tracks in 11 states (Arizona, Arkansas, Colorado, Florida, Iowa, Kansas, Massachusetts, Rhode Island, Texas, West Virginia, and Wisconsin). The canine influenza virus has been reported in 30 states and Washington, DC.
The H3N2 strain of CIV had been reported in Korea, China and Thailand, but had not been detected outside of those countries until 2015. In April of 2015, anoutbreak in Chicago, IL was determined to be caused by the H3N2 strain.
Q: Is there a vaccine?
A: The first vaccine for H3N8 canine influenza was approved in 2009, and there are several H3N8 canine influenza vaccines available. At this time, there is not an H3N2 vaccine available in the U.S. It is not known at this time whether the H3N8 vaccine will offer any protection against the H3N2 strain.
Q: How is a dog with canine influenza treated?
A: As with any disease caused by a virus, treatment is largely supportive. Good animal care practices and nutrition assist dogs in mounting an effective immune response.
The course of treatment depends on your pet's condition, including the presence or absence of a secondary bacterial infection, pneumonia, dehydration, or other medical issues (e.g., pregnancy, pre-existing respiratory disease, compromised immune system, etc.). Your veterinarian might prescribe medications, such as an antibiotic (to fight secondary infections) and/or a nonsteroidal anti-inflammatory (to reduce fever, swelling and pain). Deyhdrated pets may need fuid therapy to restore and maintain hydration. Other medications, or even hospitalization, may also be necessary for more severe cases.
Q: Is canine influenza virus transmissible from dogs to humans?
A: To date, there is no evidence of transmission of canine influenza virus from dogs to people.
Q: Do I need to be concerned about putting my dog in day care or boarding it at a kennel? Dog owners should be aware that any situation that brings dogs together increases the risk of spread of communicable illnesses. Good infection control practices can reduce that risk, so dog owners involved in shows, sports, or other activities with their dogs or who board their dogs at kennels should ask whether respiratory disease has been a problem there, and whether the facility has a plan for isolating dogs that develop respiratory disease and for notifying owners if their dogs have been exposed to dogs with respiratory disease.
As long as good infection control practices are in place, pet owners should not be overly concerned about putting dogs in training facilities, dog parks, kennels, or other areas frequented by dogs.
Q: My dog has a cough...what should I do?
A: Consult your veterinarian. Coughing can be caused by many different medical problems, and your veterinarian can examine and evaluate your dog and recommend an appropriate course of treatment. If canine influenza is suspected, treatment will usually focus on maximizing the ability of your dog's immune system to combat the virus. A typical approach might include administration of fluids if your dog is becoming dehydrated and prescribing an antimicrobial if a secondary bacterial infection is suspected.
Canine influenza virus can be spread via direct contact with respiratory secretions from infected dogs, and by contact with contaminated inanimate objects. Therefore, dog owners whose dogs are coughing or exhibiting other signs of respiratory disease should not participate in activities or bring their dogs to facilities where other dogs can be exposed to them. Clothing, equipment, surfaces, and hands should be cleaned and disinfected after exposure to dogs showing signs of respiratory disease to prevent transmission of infection to susceptible dogs. Clothing can be adequately cleaned by using a detergent at normal laundry temperatures.
Q: I manage a kennel/veterinary clinic/animal shelter/dog day care center. How do I keep canine influenza out of my facility, and if it does enter my facility, what should I do?
A: Viral disease is usually best prevented through vaccination. A vaccine against canine influenza (H3N8) has been available since 2009. It is considered a "lifestyle" vaccine, which means that the decision to vaccinate a dog against CIV is based on the risk of exposure. A veterinarian should determine which vaccinations are needed based on related risks and benefits and should administer these at least 2 weeks prior to planned visits to dog activity and care facilities (e.g., kennels, veterinary clinics, dog day care centers, training facilities, dog parks). This differs from "core" vaccines - such as distemper, parvo and rabies - that are required for all dogs, regardless of lifestyle.
Vaccination against other pathogens causing respiratory disease may help prevent more common respiratory pathogens from becoming secondary infections in a respiratory tract already compromised by influenza infection.
Routine infection control precautions are key to preventing spread of viral disease within facilities. The canine influenza virus appears to be easily killed by disinfectants (e.g., quaternary ammonium compounds and bleach solutions at a 1 to 30 dilution) in common use in veterinary clinics, boarding facilities, and animal shelters. Protocols should be established for thoroughly cleaning and disinfecting cages, bowls, and other surfaces between uses. Employees should wash their hands with soap and water (or use an alcohol-based hand cleaner if soap and water are unavailable) before and after handling each dog; after coming into contact with a dog's saliva, urine, feces, or blood; after cleaning cages; and upon arriving at and before leaving the facility (see "I work in a kennel/animal care facility. What should I do to prevent transmission of influenza virus from infected dogs to susceptible dogs?").
Animal care facility staff should be alerted to the possibility that a dog with a respiratory infection could be presented for care or boarding. If a dog with respiratory signs is presented, staff members should inquire whether the dog has recently been boarded or adopted from a shelter, has recently participated in dog-related group activities, or whether it has been exposed to other dogs known to have canine influenza or kennel cough. The dog should be brought directly into a separate examination/triage area that is reserved for dogs with respiratory signs and should not be allowed to enter the waiting room or other areas where susceptible dogs may be present.
Dogs with suspected canine influenza virus infection discovered after entry into the facility should be evaluated and treated by a veterinarian. Isolation protocols should be rigorously applied for dogs showing signs of respiratory disease, including the wearing of disposable gloves by persons handling infected dogs or cleaning contaminated cages. Respiratory disease beyond what is considered typical for a particular facility should be investigated, and the investigation should include submission of appropriate diagnostic samples (see "What diagnostic tests will tell me whether a dog has canine influenza?").
Q: What diagnostic tests will tell me whether a dog has canine influenza? What samples do I send? Where do I send the samples? How do I distinguish between canine influenza and kennel cough?
A: There is no rapid test for the specific diagnosis of acute canine influenza virus infection. Nasal or throat swabs from dogs that have been ill for less than 4 days may be sent to a diagnostic laboratory for testing. Your veterinarian may also offer other testing, such as an in-house test to detect influenza types A and B.
Antibodies to canine influenza virus may be detected as early as seven days after onset of clinical signs. Convalescent-phase samples should be collected at least two weeks after collection of the acute-phase sample. If an acute-phase sample is not available, testing a convalescent-phase sample can reveal whether a dog has been infected with or exposed to CIV at some point in the past.
For dogs that have died from pneumonia or other conditions in which CIV is suspected, additional diagnostic tests are available to your veterinarian through reference laboratories.
Q: I work in a kennel/animal care facility. What should I do to prevent transmission of influenza virus from infected dogs to susceptible dogs?
A: Canine influenza is not known to be transmissible from dogs to people. However, caretakers can inadvertently transmit canine influenza virus from infected dogs to susceptible dogs by not following good hygiene and infection control practices. To prevent spread of canine influenza virus, caretakers should take the following precautions:
- Wash hands with soap and water (if soap and water are unavailable, use an alcohol-based hand cleaner):
- Before and after handling each animal
- After coming into contact with animal saliva, urine, feces or blood
- After cleaning cages
- Before eating meals, taking breaks, smoking or leaving the facility
- Before and after using the restroom
- Wear a barrier gown over your clothes and wear gloves when handling sick animals or cleaning cages. Discard gown and gloves before working with other animals
- Consider use of goggles or face protection if splashes from contaminated surfaces may occur
- Bring a change of clothes to wear home at the end of the day
- Thoroughly clean clothes worn at the animal facility
- Do not allow animals to "kiss" you or lick your face
- Do not eat in the animal care area
- Separate newly arriving animals from animals that have been housed one week or longer.
- Routinely monitor animals for signs of illness. Separate sick animals from healthy animals, especially animals with signs of respiratory disease.
- There is no evidence of transmission of canine influenza virus from dogs to people. However, because of concerns about diseases that are transmissible from dogs to people, in general, it may be prudent for young children, the elderly, pregnant women, and immunocompromised persons to limit or avoid contact with animals that are ill.
Q: Is canine influenza transmissible to from dogs to horses or other animal species?
A: At this time, there is no evidence of transmission of H3N8 canine influenza from dogs to horses, cats, ferrets, or other animal species; the H3N2 strain has been reported to infect cats.
The infection control measures outlined in the section titled "I work in a kennel/animal care facility. What should I do to prevent transmission of influenza virus from infected dogs to susceptible dogs?" are recommended to prevent spread of the virus.