Kennel cough usually shows up 2 to 10 days after a dog meets an infected dog, and most dogs improve within one to two weeks. The catch is the contagious window: dogs can spread it before they start coughing, and dogs infected with Bordetella can keep shedding the bacteria for weeks after the cough is gone.
Most cases stay mild. A coughing dog that is breathing fast or hard, won't eat, seems flat or has a fever needs a vet the same day, because those are signs the infection may have reached the lungs.
That timing matters most in the holiday boarding season, from Thanksgiving (the fourth Thursday in November) through New Year. A dog boarded for a long weekend often starts coughing a few days after it comes home, and the vaccines some kennels ask for need weeks, not days, to plan.
The kennel cough timeline
Stage | Typical timing | What it means for you |
|---|---|---|
Exposure | Day 0: boarding, daycare, groomer, dog park, a vet waiting room | Your dog may already be contagious before any cough |
First signs | Usually 2 to 10 days later; some sources say up to 14 | The cough often starts after you have picked your dog up |
Worst days | Often the first few days of coughing | Merck notes severity usually eases over the first 5 days |
Recovery | Most mild cases: about 7 to 10 days, up to 2 weeks | Merck says the illness can run 10 to 20 days |
Recheck point | No clear improvement after about a week | Call your vet; something else may be going on |
Contagious tail | With Bordetella: up to 8 weeks or longer after signs stop | Keep away from other dogs until your vet says it's fine |
The sources don't agree to the day, which is expected for an illness caused by several different germs. Cornell's veterinary college puts the incubation period at 2 to 10 days, Veterinary Partner (VIN) at 2 to 14. The AVMA says most dogs fully recover within 7 to 10 days, while the Merck Veterinary Manual notes the disease can persist for 10 to 20 days. The practical version: expect one to two weeks, and call your vet if your dog isn't clearly better after about a week.
The long contagious tail is specific to Bordetella bronchiseptica. Cornell says dogs with Bordetella can stay contagious for up to eight weeks after their signs clear, and potentially longer.
What kennel cough is and what causes it
Kennel cough is the everyday name for canine infectious respiratory disease complex (CIRDC), also called canine infectious tracheobronchitis. It inflames the windpipe (trachea) and the airways branching off it (bronchi), and in more serious cases it reaches the lungs.
It isn't one germ. Several bacteria and viruses can cause it, and a dog is often infected with two or more at once. The ones most often involved are:
- Bordetella bronchiseptica, a bacterium
- canine parainfluenza virus
- canine adenovirus type 2
Others that can join in include canine influenza (H3N2 and H3N8), canine respiratory coronavirus, canine herpesvirus, Mycoplasma species, Streptococcus equi subspecies zooepidemicus, and less often canine distemper virus, the most serious of the group.
Because so many germs are involved, a vaccinated dog can still catch kennel cough. The vaccines cover the main players, not all of them.
How dogs catch it
Kennel cough spreads mostly through the air when an infected dog coughs or sneezes. It also passes by nose-to-nose contact and licking, and on shared toys, bedding, water bowls, hands and clothing.
The AVMA points out that most dogs are contagious before they show signs, which is why outbreaks move fast wherever dogs share air for hours: boarding kennels, daycares, grooming salons, shelters, training classes, dog shows, dog parks and vet clinics.
Signs: what a typical case looks like
The classic sign is a sudden, frequent, honking cough, often compared to a goose honk. Many dogs retch or gag at the end of a coughing fit and may bring up a little white foam, so owners often think something is stuck in the throat or that the dog is vomiting.
Other common signs:
- coughing that gets worse with exercise or excitement
- sneezing
- a runny nose or watery eyes
Some dogs also run a mild fever, seem a bit tired or eat less. Not every infected dog coughs at all. In a typical case the dog still acts mostly like itself between coughing fits.
When it's more than a cough
Kennel cough can turn into pneumonia, a lung infection. Merck, Cornell and the AVMA describe the same warning signs:
- fast or labored breathing
- lethargy (your dog is flat, not just tired)
- not eating
- fever
- a moist or productive cough
- thick, colored discharge from the nose
Severe disease is more likely in puppies, older dogs and dogs with other health problems. Dogs with existing airway or lung disease or weak immunity, unvaccinated dogs, and dogs whose infection includes distemper are at higher risk too.
Call now (same day, or the emergency clinic after hours):
- breathing that is fast or hard while your dog is resting
- blue or gray gums (a sign of low oxygen and an emergency)
- a coughing dog that is listless, not eating or feverish
See your vet soon (same day if you can):
- a coughing puppy, or a coughing dog that is older or has heart or lung disease
- any new honking cough, especially after boarding, daycare or a dog park visit
- a cough that isn't clearly improving after about a week
Mention at your next visit:
- your dog had kennel cough, recovered fully, and you want to plan vaccines before the next boarding stay
Keeping a coughing dog away from other dogs
The AVMA advises keeping a dog with suspected kennel cough away from other dogs until it has fully recovered. In practice:
- Cancel daycare, boarding, grooming and group classes, and tell the facility so they can watch the other dogs.
- Skip the dog park and on-leash greetings. Your dog can look healthy and still be contagious.
- Call the clinic before you go in. The AVMA suggests describing the signs on the phone first, so the team can see your dog without exposing other patients.
- Keep bowls, toys and bedding to your own household.
When can your dog go back to daycare? Because of that Bordetella tail, ask your vet, and check the facility's own rule.
What your vet does
Most mild cases are diagnosed from the history and an exam: a typical cough, recent contact with other dogs, and no sign of something else.
Tests aren't needed for most mild cases. Your vet is more likely to suggest them if your dog is very sick, getting worse despite care, or part of an outbreak. They can include chest X-rays to check for pneumonia and rule out other causes, nose or throat swabs to identify the germs (PCR testing), and sometimes blood work.
There is no specific drug that cures kennel cough. Treatment depends on how sick the dog is:
- Mild cases: rest and supportive care. The AVMA describes this as encouraging rest and avoiding excitement and neck leashes, so walk your dog on a harness for now.
- A cough that stops your dog sleeping: some dogs get a prescription cough suppressant. Vets don't use these when the cough is productive or the dog has pneumonia, because the dog needs to clear the airways.
- Sicker dogs: medicine for fever and inflammation and fluids for dehydration, as your vet decides.
- Antibiotics: usually not needed, because many cases are viral. Vets use them when there are signs of bacterial pneumonia, which the AVMA says includes illness lasting more than 10 days.
- Pneumonia: may mean hospital care with IV fluids, antibiotics and oxygen.
Don't reach for a human cough or cold medicine. Many contain decongestants or pain relievers that can harm dogs, and the same goes for home cough remedies: give only what your vet prescribes.
A cough that won't resolve can mean pneumonia or a different problem altogether, such as a collapsing windpipe, bronchitis or heart disease. That's why the one-week recheck matters.
Kennel cough vaccines
Vaccines reduce the chance of illness, make severe disease less likely, and make a vaccinated dog less likely to spread the infection. Cornell compares them to a human flu shot: they don't always stop the infection, but they lessen it.
Vaccine | Covers | How it's given | Starting series (AAHA) |
|---|---|---|---|
Core combination (often called DHPP or DA2PP) | Distemper, adenovirus type 2, parainfluenza, parvovirus | Injection | Puppy series, then boosters |
Bordetella, intranasal | Bordetella plus parainfluenza (some products also adenovirus type 2) | Drops in the nose | One dose |
Bordetella, oral | Bordetella only | Liquid in the cheek pouch | One dose |
Bordetella, injectable | Bordetella only | Injection | Two doses, 2 to 4 weeks apart |
Canine influenza (H3N2/H3N8) | Canine flu | Injection | Two doses, 2 to 4 weeks apart |
Bordetella and canine influenza vaccines are "noncore": your vet recommends them based on your dog's lifestyle, for example regular boarding or daycare. Boosters are yearly, as the AAHA canine vaccination guidelines recommend.
Two timing details matter before boarding:
- How fast protection starts. In laboratory challenge studies, some run by the vaccine makers, protection was shown within 72 hours of a nose-drop vaccine and 7 days after one oral dose. A first injectable series needs both doses. Our oral Bordetella vaccine post covers the routes and those studies in detail.
- How long it lasts. AAHA notes that real-world protection against Bordetella may be as short as about 6 months, so for high-risk dogs a nose-drop booster before boarding may help. Your vet decides.
A vaccine won't help a dog that is already incubating kennel cough, so it can't be a last-minute fix.
Before you book holiday boarding: a checklist
- Ask the facility for its vaccine rules early. Many boarding kennels and daycares require proof of certain vaccines. Ask which ones, and how recent they need to be.
- Book a vet visit well ahead. A two-dose injectable Bordetella or canine flu series means doses 2 to 4 weeks apart, so start at least a month before the trip. AAHA also suggests a pre-boarding visit to check your dog is healthy and up to date.
- Ask how the facility handles a coughing dog, and whether dogs share water bowls or play in big groups.
- Don't board a dog that is coughing. Call your vet and the facility instead; it protects the other dogs and gets your dog seen.
- Check for outbreaks where you're going. The AVMA suggests delaying or avoiding travel with your dog to places where respiratory outbreaks are being reported.
- Watch for 2 weeks after pickup. Signs can start up to 10 to 14 days after exposure. A new cough means a call to your vet and no daycare until it's sorted out.
Quick answers
Can people catch kennel cough?
Rarely. Of the kennel cough germs, only Bordetella bronchiseptica is known to infect people, and those cases are extremely rare, mostly in people with severely weakened immune systems. If someone at home is immunocompromised, tell your vet; Cornell suggests the injectable Bordetella vaccine may be the better choice in that household.
Can cats get it?
Some of the germs, including Bordetella and canine influenza, can infect cats.
My dog was vaccinated. Why does it have kennel cough?
The vaccines don't cover every germ in the complex, and they lessen illness rather than block every infection. Vaccinated dogs that do get sick often have milder signs.
Is it kennel cough or canine flu?
You can't tell from the cough. Canine influenza is one of the causes of kennel cough and can be more severe. Read more in our canine influenza post.
Sources
- AVMA: Canine infectious respiratory disease complex (Kennel cough)
- Merck Veterinary Manual: Kennel Cough (Canine Infectious Tracheobronchitis)
- Cornell University College of Veterinary Medicine: Bordetellosis
- Cornell University College of Veterinary Medicine: The risks of kennel cough
- AAHA 2022 Canine Vaccination Guidelines: Bordetella, Canine Parainfluenza, and Canine Influenza
- AAHA 2022 Canine Vaccination Guidelines: Core and noncore canine vaccines
- AAHA: 6 tips to prepare your pet for boarding
- Veterinary Partner (VIN): Kennel Cough in Dogs
- VCA Animal Hospitals: Kennel Cough in Puppies
- VCA Animal Hospitals: Cyanosis in Dogs
- Mar Vista Animal Medical Center: Canine Chronic Bronchitis
- Scott-Garrard et al., Vet Record Open (2018): Onset of immunity of oral and intranasal Bordetella vaccines
- Gore et al., Veterinary Record (2005): Intranasal kennel cough vaccine protecting dogs within 72 hours
This article is for general information and is not a substitute for advice from your veterinarian.
