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Does Your Dog Need a Flu Shot?

“Sick as a dog” isn’t just a phrase.

by Sara Greenslit, DVM
Updated September 7, 2022
a dog at the vet getting a check-up
Marco Govel / Stocksy

Your pet wants you to read our newsletter. (Then give them a treat.)

Every year, as temperatures drop, we humans brace ourselves for flu season. In recent years, with COVID-19 also a threat, we’ve had to be extra vigilant with vaccines and other safety precautions. Basically, this is life these days.

To be clear, this applies to everyone in the fam, even the dog.

You might not have thought about your pup’s risk of catching the flu, but after outbreaks in the Greenville, South Carolina, and Birmingham, Alabama areas have reported outbreaks of canine influenza this past month, now is a good time to learn more about it. In addition, the County of Los Angeles Department of Public Health reported an outbreak from June 2021 through January of this year.

The illness is highly contagious, and while most dogs recover, complications can arise. Here's everything you need to know.

What is Canine Influenza?

Influenza viruses are named for the way the hemagglutinin (HA) and neuraminidase (NA) proteins combine, and canine influenza comes in two strains: H3N8 and H3N2. Only 80 percent of dogs affected by canine influenza show flu-like symptoms, but all infected dogs can spread the infection. The fatality rate for influenza in dogs is less than 10 percent.

The H3N8 strain first appeared in Florida in 2004 and was suspected of having jumped from racehorses to Greyhounds. Then, in 2015, dogs in Chicago were diagnosed with H3N2. Previously known to exist only in South Korea, China, and Thailand, the latter strain is thought to have been transmitted to dogs by infected birds in live Asian bird markets, then possibly brought to the U.S. via imported dogs.

Dog flu targets the cells in the respiratory tract, which reaches from the nose to the small airways of the lungs, and causes mild-to-severe inflammation. Recovery takes two to three weeks, and while a dog of any age or breed can contract it, some may be at higher risk — particularly puppies, pregnant dogs, dogs with respiratory disease or tracheal collapse, and those on immunosuppressive medication.

How is Canine Flu Spread?

During the two-to four-day incubation period before dogs show any signs of illness, the dog flu can spread through commonplace activities such as being patted on the head, sharing a tennis ball or water bowl, or a nose-to-nose greeting. Again, there is no “flu season” for dogs; they can contract this virus any time of the year. Most vets recommend pet parents isolate dogs with canine influenza for 21 days to reduce the risk of transmission.

What are the Symptoms of Canine Influenza?

Symptoms of the flu differ between dogs, so not all of them will display the same signs, but these are the most common ones: 

  • A soft, dry cough that persists for 10 to 21 days despite treatment

  • Nasal congestion and/or thick nasal discharge

  • Fever

  • Lethargy

  • Poor appetite

If your dog shows signs of the flu, take them to your veterinarian. To reduce its spread, ask the reception staff if you should stay in the car until they're ready for the exam, and enter and exit by a side door if possible.

Influenza can be mistaken for kennel cough (infectious tracheobronchitis). Bacteria, such as bordetella and mycoplasma and viruses such as parainfluenza, canine distemper, and canine adenovirus-2 present similarly.

Dogs with influenza, however, often spike fevers. You can monitor your pup’s temperature using a rectal thermometer, ideally every four to six hours to make sure it stays below 103 degrees Fahrenheit. A high-grade fever (104 degrees Fahrenheit to 106 degrees Fahrenheit) and increased respiratory rate and effort could mean that your dog is developing pneumonia; your vet will most likely recommend chest x-rays to screen for this.

Treatment for the flu is supportive care. Based on your dog’s exam and signs, it may include antibiotics for secondary infections, fluid therapy, nutritional support, appetite stimulants, and dog-specific fever-reducing anti-inflammatory drugs. (Don’t share yours — aspirin, ibuprofen, acetaminophen, and other human pain killers can be toxic for dogs.) Most importantly, keep your sick dog home and away from other dogs for at least four weeks. If you have multiple dogs, even those who seem healthy should also be quarantined.

Is There a Dog Flu Shot, and Should My Dog Get it?

The good news is, the dog flu shot is widely available. The first vaccine was approved in 2009 and initial tests showed no side effects.

A dog’s risk of exposure to the virus increases if they spend time at a kennel or go to daycare, the groomer, dog parks or dog-friendly gatherings, or if a human in the house works around dogs. 

The vaccine may not prevent an infection, but it can reduce its severity and duration. A bivalent vaccine that offers protection against both strains is also available. Ask your veterinarian about what's best for your dog.

Tips for Preventing the Dog Flu

The best thing you can do to keep your dog healthy is maintain their core vaccines (DHPP and bordetella), which will help them avoid a secondary respiratory infection. Other preventive tips are: 

  • Bring your own water to the dog park.

  • When you come home, take your shoes off at the door and wash your hands immediately. (Yes, before you greet your pets. It’s also a good practice for your own health.)

  • Leave leashes and dog coats at the door. 

  • Keep surfaces and textiles clean. Canine influenza tends to survive no longer than 48 hours in the environment and can be inactivated by common cleaners, such as a bleach-water solution. Fabric items that have come in contact with sick dogs should be washed in hot water with regular detergent.

Can People Get the Flu From Dogs?

Currently, there is no data to suggest that the influenza virus is zoonotic — meaning that it can spread from dogs to humans — but because dogs may carry other viruses that are, it makes sense for young, elderly, pregnant, or immunocompromised people to avoid contact with ill animals.

While humans may not be susceptible, other animals might be. In 2016, cats in an Indiana shelter contracted canine influenza H3N2, and experts suspected dog-to-cat transmission. Sick cats show symptoms including nasal discharge, congestion, fatigue, lip-smacking, and excess salivation. 

So far, there is no indication that the H3N8 strain can be transmitted from dogs to horses, ferrets, or other animal species. However, there is some proof that guinea pigs and ferrets can become infected with H3N2. Contact your veterinarian if you have more questions.

Like most infectious diseases, when it comes to dog flu, prevention is key. For both our dogs’ benefit and our own, it’s best to follow the basic rules: wash hands frequently, keep up-to-date on vaccines, and stay home.

Nearly three years into a global pandemic, we should all be familiar with those simple tenants *searches frantically for hand sanitizer*.

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sara greenslit

Sara Greenslit, DVM

Sara Greenslit, DVM, CVA, is a small-animal veterinarian and writer who lives and practices in Madison, Wisc.