Canine Influenza FAQ
Questions, Answers, and Interim Guidelines
A: Canine influenza (CI), or dog flu, is a highly contagious respiratory infection of dogs that is caused by an influenza A virus. In the U.S., canine influenza has been caused by two influenza strains. The first strain reported in the United States, beginning in 2004, was an H3N8 influenza A virus. This strain is closely related to the virus that causes equine influenza, and it is thought that the equine influenza virus mutated to produce the canine strain. In 2015, an outbreak that started in Chicago was caused by a separate canine influenza virus, H3N2. The strain causing the 2015 outbreak was almost genetically identical to an H3N2 strain previously reported only in Asia – specifically, Korea, China and Thailand. In Asia. This H3N2 strain is believed to have resulted from the direct transfer of an avian influenza virus – possibly from among viruses circulating in live bird markets – to dogs. Since March 2015, thousands of dogs have been confirmed positive for H3N2 canine influenza across the U.S.
- 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 reduced appetite and a 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.
A: Because this is still an emerging disease and dogs in the U.S. have not been exposed to it before, almost all dogs, regardless of breed or age, lack immunity to it and are susceptible to infection if exposed to the active virus. Virtually all dogs exposed to the virus become infected, and nearly 80% show clinical signs of disease, though most exhibit the mild form described above.
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 recover in 2-3 weeks.
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 at least 40 states and Washington, DC.
A: The first canine vaccine for H3N8 canine influenza was approved in 2009, and there are several H3N8 canine influenza vaccines available. It is not known whether the H3N8 vaccine will offer any protection against the H3N2 strain. Canine influenza vaccines are considered "lifestyle" vaccines, meaning the decision to vaccinate is based on a dog’s risk of exposure. Dog owners should consult their veterinarian to determine whether vaccination is needed.
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.
A: To date, there is no evidence of transmission of canine influenza virus from dogs to people.
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, however, has been reported in Asia to infect cats, and there’s also some evidence that guinea pigs and ferrets can become infected.
A: 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.
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 (via barking, coughing or sneezing), 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 (including shoes), 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.
A: Viral disease is usually best prevented through vaccination. A vaccine against H3N8 canine influenza has been available since 2009, and H3N2 vaccines were conditionally approved in late 2015. 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 whether vaccination is needed based on related risks and benefits, and should administer these vaccinations 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.
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 3 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.
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):
- Upon arriving at the facility
- 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.
Iowa State University Center for Food Security & Public Health
University of Florida College of Veterinary Medicine
Cornell University Veterinary Diagnostic Laboratory
Centers for Disease Control and Prevention