Medically reviewed by Dr. Dean Severidt, Director of Medical Excellence, October 9, 2026.
When cold and flu season rolls in, most of us worry about ourselves and our families getting sick. Here’s something that surprises a lot of pet parents: dogs can catch the flu, too. It isn’t the same virus that sends you to bed. Dogs have their own version, called canine influenza, and it spreads easily anywhere dogs spend time together.
Most cases are mild, and knowing the basics makes it much easier to keep your dog healthy. At Canine Fitness & Fun Center in Denver, CO, we want you to know what to watch for, when to call your veterinarian, and how to time the vaccine so your dog is ready for the holiday season ahead.
Dog Flu at a Glance
What it is: a contagious respiratory illness that spreads easily wherever dogs spend time together
What to watch for: a lingering cough, sneezing, nasal discharge, fever, low energy, and less interest in food
When to call your veterinarian: as soon as you notice a cough or any of these symptoms
When to vaccinate: about six weeks before boarding, daycare, or travel, since the two-dose series takes three to six weeks to work
What Is Canine Influenza?
Canine influenza, often called dog flu, is a highly contagious respiratory disease caused by two flu viruses that are specific to dogs.
Most dogs have never been exposed to either virus, so they have no built-in immunity. Nearly every dog who’s exposed becomes infected, whatever their breed, age, or overall health. According to the American Veterinary Medical Association (AVMA), about 80% develop symptoms. The other 20% look perfectly healthy but can still pass the virus along.
There’s no evidence that people can catch canine influenza. Cats occasionally can, though it’s uncommon and seen mostly in shelters.
Is There a Dog Flu Season?
Not really. Human flu peaks in fall and winter, but canine influenza can show up at any time of year. It tends to appear in local outbreaks that flare up and then fade.
So why talk about it now? The holidays are when dogs mix the most. Boarding, daycare, grooming appointments, and travel all pick up around Denver and Aurora this time of year. More dogs sharing space means more chances for a respiratory virus to move from one dog to the next.
Protecting Every Dog at Canine Fitness & Fun Center in Denver, CO
At Canine Fitness & Fun Center, dogs spend their days playing, swimming, and resting side by side, so keeping shared spaces healthy is a priority for our team. Whether your dog joins us for daycare, overnight boarding, grooming, or a swim in our 25-foot dog pool, knowing the signs of canine influenza helps us protect every dog in our care. Visit us at 5390 E Evans Ave, Denver, CO 80222, call us at (720) 902-7294, or email us to check our vaccination requirements or share your dog’s vaccination records.
How Dog Flu Spreads
Canine influenza travels in respiratory droplets. Your dog can pick it up through:
Nose-to-nose greetings, licking, and play
Coughing, sneezing, and barking from an infected dog nearby
Shared items such as water bowls, toys, leashes, and kennel surfaces
The hands and clothing of people who’ve handled an infected dog
The virus can survive for a day or two on surfaces, but common disinfectants kill it easily. Timing is the tricky part. Dogs are most contagious in the first few days after exposure, before they show any signs, and they can keep spreading the virus for up to four weeks after they were first exposed.
Symptoms of Canine Influenza in Dogs
Signs can appear anywhere from one to eight days after exposure, depending on the strain. Watch for:
A cough that lingers, often for 10 to 21 days
Sneezing
Thick nasal discharge
Runny eyes
Fever, often 104 to 105 degrees Fahrenheit
Low energy
Less interest in food
Dog flu is one of several illnesses behind canine cough, often called kennel cough. They look alike, so only a lab test, usually a nose or throat swab, can tell which one your dog has.
Most dogs have a mild illness and recover fully within two to three weeks. There’s no medication that treats the virus itself, so care focuses on comfort: rest, plenty of fluids, and good nutrition while your dog’s body does the work. About 10% to 20%, according to the AVMA, develop complications such as bacterial pneumonia and need more care. Puppies, senior dogs, and dogs with other health conditions are most at risk.
When should I call my veterinarian?
Call your veterinarian as soon as you notice a cough or any of the signs above. If your dog is having trouble breathing, seems extremely tired, or stops eating, don’t wait. Please call before you bring your dog in so the clinic can keep other patients from being exposed. In the meantime:
Keep your dog home and away from other dogs
Let the team at Canine Fitness & Fun Center know, along with any other daycare, boarding, grooming, or training facility your dog visited recently
Ask your veterinarian when it’s safe for your dog to be around other dogs again. As a precaution, the AVMA recommends keeping them apart for four weeks from the day signs first appear
When Should I Vaccinate My Dog Against Canine Influenza?
Earlier than you’d think. The vaccine needs time to work, so the calendar matters as much as the shot.
How does the vaccine schedule work?
The canine influenza vaccine is given as two doses, two to four weeks apart. Protection builds one to two weeks after the second dose, and a single dose is unlikely to protect a dog in a group setting. Add it up and the full series takes three to six weeks to do its job.
If your dog will be boarding, going to daycare, or traveling, aim to start about six weeks ahead. If your dog’s stay is sooner than six weeks out, talk with your veterinarian now about timing. After the first series, one booster a year keeps protection current.
One more thing worth knowing: the vaccine won’t always prevent infection. What it does is make illness milder and shorter, and it reduces how much virus a dog spreads to others.
Which dogs benefit most from the dog flu vaccine?
Canine influenza is a lifestyle vaccine. The American Animal Hospital Association (AAHA) recommends deciding based on each dog’s risk, and veterinarians often suggest it for dogs who regularly:
Stay at boarding facilities
Go to daycare or dog parks
Visit the groomer
Take part in dog shows or sporting events
Travel
AAHA also recommends the vaccine that covers both strains. If your dog fits any of those descriptions, ask your veterinarian whether it makes sense. Then check the vaccine requirements at Canine Fitness & Fun Center before your dog’s next visit so there are no surprises at drop-off.
Everyday Ways to Lower Your Dog’s Risk
Vaccines are one layer of protection. Simple habits are another:
Keep a coughing or sneezing dog home
Steer clear of dogs who are obviously sick
Wash your hands after petting other dogs
Skip shared water bowls and toys outside your home
Watch for canine influenza alerts around Denver, and avoid places where dogs gather until an outbreak passes
It’s also fair to ask any facility how it handles infection control. The AVMA suggests asking about routine cleaning, whether respiratory illness has been a problem, how sick dogs are separated, and how pet parents are notified. We welcome those questions at Canine Fitness & Fun Center. Ask us anytime or see how we care for our boarding guests.
How Canine Fitness & Fun Center Helps Keep Dogs Healthy
Knowing how dog flu spreads shapes how we care for our guests. Here’s how we lower the risk at Canine Fitness & Fun Center:
Vaccination. We highly recommend the canine influenza vaccine for every dog who visits us. Dogs in our care spend time near other dogs, which is exactly when the vaccine matters most.
Cleaning protocols. We clean with pet-safe products and follow protocols designed to limit the spread of illness throughout the center.
Separate care. If a dog shows signs of illness, we separate them from the other dogs and call you to let you know.
No place where dogs share space can bring the risk down to zero, which is why the signs and vaccine timing above matter so much.
Frequently Asked Questions About Canine Influenza
Can I catch canine influenza from my dog?
No. Canine influenza isn’t known to spread from dogs to people. Cats can occasionally catch it, but that’s uncommon.
How long is a dog with canine influenza contagious?
Up to four weeks after they were first exposed, and they’re most contagious early on, often before any symptoms show.
How long does the canine influenza vaccine take to work?
Plan on three to six weeks from the first dose. Your dog needs two doses spaced two to four weeks apart, then another week or two for protection to build. If your dog has a stay coming up at Canine Fitness & Fun Center, aim to start about six weeks ahead. If it’s sooner than that, talk with your veterinarian now about timing.
Is dog flu the same as kennel cough?
Dog flu is one cause of it. Kennel cough is the everyday name for a contagious cough in dogs, and several viruses and bacteria can be behind it, including canine influenza. The signs look alike, so only a lab test can tell which one your dog has. Call your veterinarian if your dog starts coughing.
Get Your Dog Ready for Holiday Boarding in Denver, CO
Holiday plans come together fast. If your dog will be boarding, playing at daycare, or traveling in the next couple of months, talk with your veterinarian about canine influenza now. If the stay is less than six weeks away, they can help you plan around the timing.
Have questions about our vaccine requirements or your dog’s upcoming stay? Contact Canine Fitness & Fun Center and we’ll walk you through it.
Sources
American Veterinary Medical Association. (2026). “Canine influenza.” AVMA. https://www.avma.org/resources-tools/pet-owners/petcare/canine-influenza
American Veterinary Medical Association. (2026). “Canine influenza: Veterinary resources.” AVMA. https://www.avma.org/resources-tools/animal-health-and-welfare/animal-health/canine-influenza-veterinary-resources
American Animal Hospital Association. (2022). “Key Vaccination: Bordetella, Canine Parainfluenza, and Canine Influenza.” AAHA. https://www.aaha.org/resources/2022-aaha-canine-vaccination-guidelines/bordetella-canine-parainfluenza-and-canine-influenza/
University of Florida Shelter Medicine Program. (2017). “Canine influenza confirmed in 8 states; should shelters and rescue groups be vaccinating?” University of Florida College of Veterinary Medicine. https://sheltermedicine.vetmed.ufl.edu/2017/06/06/canine-influenza-confirmed-in-8-states-should-shelters-and-rescue-groups-be-vaccinating/
Centers for Disease Control and Prevention. (2024). “About Dog Flu.” CDC. https://www.cdc.gov/flu-in-animals/about/canine-flu.html