If your dog is coughing, has a runny nose, and seems more tired than usual, they could be suffering from canine influenza, a highly infectious virus. Fortunately, most cases of doggy flu are mild, but learning about the signs and taking appropriate precautions can protect your pet and help to slow the spread of an outbreak in your area.
Key Points
What Is Canine Influenza?
Canine influenza virus (CIV), commonly referred to as dog flu, is a highly contagious infection of the respiratory system (nose, mouth, throat, airways, and lungs). There are two known main strains. The H3N8 influenza A strain, thought to have originated in equines and then mutated to produce a canine strain, was first reported in the U.S. in 2004. A second strain, first reported in the U.S. in 2015, is now more common. The H3N2 influenza A strain, likely originating in Asia, is believed to be an avian (bird) influenza virus that crossed over to dogs.
How Serious Is Canine Influenza?
While outbreaks of canine influenza aren’t particularly common in the U.S., they are concerning because of their highly infectious nature. “Canine influenza can spread quite rapidly between animals, with almost 100% of animals that are exposed becoming infected,” says Dr. Stephen Cole, Assistant Professor of Clinical Microbiology and Director of Penn Vet’s Clinical Infectious Disease Laboratory.
He explains that many cases go undiagnosed, meaning the virus often spreads unknowingly. Low vaccination rates and low baseline levels of immunity among dogs not exposed to this relatively rare virus also contribute to canine influenza rapidly gaining a foothold. Because these types of viruses can easily adapt, there is also a risk that strains may become more serious and infectious over time.
Fortunately, since its introduction to the U.S., outbreaks of canine influenza have been localized rather than spreading nationwide. It’s also reassuring that while any dog can be infected, most have mild to moderate symptoms and recover rapidly. The mortality rate of canine influenza in the U.S. is estimated to be between 1-5%, according to Dr. Cole. “Those most at risk of severe infections or complications from the infection appear to be older dogs with underlying heart or lung disease, or breeds like Pugs and Boxers,” he adds.
How Is Canine Influenza Spread?
Your dog is at risk of contracting canine influenza if they have direct contact with an infected dog or their respiratory secretions. Nasal discharge, sneezing, coughing, or barking widely disperse infectious droplets that can be immediately inhaled or survive for up to 48 hours on surfaces, such as floors, bowls, toys, bedding, or clothing. While humans can’t contract canine influenza, we can carry infectious droplets on our skin for 12 hours.
Infected dogs can be contagious before symptoms appear and up to a month after initial exposure. Many never showing any obvious signs of being sick, but still able to pass on the virus.
What Are the Signs and Symptoms of Canine Influenza?
While most dogs that contract canine influenza (around 80%) exhibit symptoms, these are usually mild and clear up within 1 to 3 weeks. “Similar to influenza in people, in a dog with canine influenza, we would expect to find signs such as nasal or ocular discharge, coughing, sneezing, fever, or rapid breathing,” says Dr. Ian DeStefano, emergency and critical care veterinarian and assistant clinical professor at Cummings School of Veterinary Medicine at Tufts University. Lethargy and a lack of appetite are also common.
If your dog has a cough, it will often be soft and moist. However, some dogs can have a dry, honking cough, similar to the one commonly associated with kennel cough, another contagious respiratory infection in dogs.
If your dog develops a more severe form of canine influenza, pneumonia (an infection of the lungs) or other secondary bacterial infections can accompany it. Dr. Cole recommends seeing a veterinarian immediately if your dog is having breathing difficulties. High fevers (from 104⁰F to 106⁰F) are also a serious cause for concern.
How Is Canine Influenza Diagnosed?
Your veterinarian may suspect canine influenza based on your dog’s history and if there is a known outbreak in your area. However, the only way to definitively diagnose canine influenza is through a laboratory test, because the symptoms are similar to other bacterial and viral respiratory infections. You usually have to wait 24 to 48 hours for the results.
“Typically, your veterinarian needs to collect a nasal swab and/or a throat swab from your dog,” Dr. Cole says. “Hopefully, in the future, a rapid test will be widely available to veterinarians, but this is not currently available in most clinics.”
If your dog’s symptoms are mild and you can isolate them, your veterinarian may feel that testing is unnecessary. However, testing may be advised if your dog has more serious symptoms, if their lifestyle could lead to spread, or if there are concerns about an outbreak.
If you suspect your dog has canine influenza, your veterinarian will also advise on protocols to follow when visiting the clinic to reduce the risk of spreading infection.
How Is Canine Influenza Treated?
For mild cases of canine influenza, your dog may benefit from simply being allowed to rest. Other supportive measures, such as cough suppressants or dietary changes, may also be appropriate. Isolating your dog from other dogs for up to 21 days is essential to reduce the risk of spreading the infection.
“There usually aren’t specific therapies recommended, as there is no direct evidence that direct treatments like antiviral medications help,” Dr. DeStefano says. “Just like when we have a bad head cold, symptomatic care, or even just watchful waiting in many cases is all that’s warranted.”
He explains that hospitalization may be necessary to ensure a dog stays hydrated in more advanced cases where they refuse to eat or drink. “If severe respiratory signs are noted, oxygen therapy may be provided.”
Dr. Cole explains that in rare cases, when dogs go on to develop severe bacterial pneumonia, it can be life-threatening, and treatment can be challenging. If a course of antibiotics isn’t enough, your veterinarian may admit your dog to the hospital for more intensive care.
What to Do If There Is a Canine Influenza Outbreak in Your Area
First of all, don’t panic! While there are sensible precautions you can take when an outbreak occurs, if your dog does contract canine influenza, they’ll most likely recover within a few weeks without major incident.
“Probably the most effective thing would be to keep [your dog] away from other dogs and avoid group settings (e.g. boarding, grooming, daycare), but, of course, this may not always be possible,” Dr. Cole says. Good hygiene practices, such as washing hands after handling dogs and avoiding shared dog bowls, toys, and bedding outside the home, can also help.
Dr. Cole explains that vaccination is the best tool to protect dogs who routinely interact with other dogs or visit these group settings. “Like the human flu vaccine, it does not completely prevent the disease, but can help to shorten the duration of disease and help prevent severe manifestations.” He recommends talking with your veterinarian to assess your dog’s risk and to make a decision based on these discussions.
Dr. DeStefano points out that vaccination can also help reduce the risk of transmission and offer additional peace of mind during an outbreak for dogs that may be at increased risk of developing complications from canine influenza. “While we don’t have abundant information to say who is at risk of severe disease, the things that come to mind to me would be those with known underlying conditions (lung diseases, like pulmonary hypertension, or heart disease), or in certain breeds, like Bulldogs, Pugs, Shih Tzus, etc.,” he says.
A single vaccination prevents both the H3N2 and H3N8 strains of canine influenza. Your dog will require a booster shot two weeks after the first vaccine, and it takes 3 to 4 weeks to provide immunity.
This article is intended solely as general guidance, and does not constitute health or other professional advice. Individual situations and applicable laws vary by jurisdiction, and you are encouraged to obtain appropriate advice from qualified professionals in the applicable jurisdictions. We make no representations or warranties concerning any course of action taken by any person following or otherwise using the information offered or provided in this article, including any such information associated with and provided in connection with third-party products, and we will not be liable for any direct, indirect, consequential, special, exemplary or other damages that may result, including but not limited to economic loss, injury, illness or death.