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Pharmaceuticals2026-06-10 · 11 min read

Kennel Cough in Dogs (CIRDC): Causes, Treatment, Vaccines, and When It Becomes Dangerous

Kennel cough (CIRDC) is a complex of respiratory infections, not one disease. Covers causes, diagnosis, treatment, vaccines, and when a cough becomes an emergency.

Ran Chen
Ran Chen
Founder, VetMedGuide. Life-sciences operator and 10× global market-access lead.
Published

That dry, hacking cough your dog picked up after boarding — the one that sounds like something is stuck in their throat — is probably kennel cough. The name is familiar to most dog owners, but the reality is more complex than a single bug going around the kennel.

Kennel cough is the common name for canine infectious respiratory disease complex (CIRDC), a group of viral and bacterial pathogens that cause similar respiratory signs. Most cases are mild and self-limiting, but some progress to pneumonia. Understanding what causes CIRDC, how it spreads, and when to seek veterinary care can help you protect your dog and respond appropriately if they get sick.

What Is CIRDC?

CIRDC is a clinical syndrome — a collection of respiratory diseases caused by multiple infectious agents, often working in combination. The disease has gone by many names over the years: kennel cough, canine cough, infectious tracheobronchitis, and canine infectious respiratory disease (CIRD). CIRDC is now the preferred veterinary term because it captures the multi-pathogen nature of the condition.

At least nine bacterial and viral pathogens have been identified as contributors:

Bacterial:

  • Bordetella bronchiseptica — the most commonly recognized bacterial cause and the target of the "kennel cough vaccine"
  • Mycoplasma species — role is not fully established but frequently identified in co-infections
  • Streptococcus equi subspecies zooepidemicus — less common but can cause severe hemorrhagic pneumonia

Viral:

  • Canine parainfluenza virus (CPIV)
  • Canine adenovirus type 2 (CAV-2)
  • Canine influenza viruses (H3N2 and H3N8)
  • Canine respiratory coronavirus
  • Canine herpesvirus
  • Canine distemper virus (in unvaccinated dogs)
  • Canine pneumovirus

Co-infections are common. A dog with CIRDC is often infected with more than one pathogen simultaneously, which can make clinical signs more severe and treatment more nuanced.

How Kennel Cough Spreads

CIRDC is highly contagious. Transmission occurs through:

  • Airborne droplets — when an infected dog coughs or sneezes, releasing respiratory secretions into the air
  • Direct contact — nose-to-nose contact with an infected dog
  • Contaminated surfaces — shared water bowls, toys, kennel floors, door handles, and human hands

The incubation period is typically 2–10 days, meaning a dog can be infected but not yet showing signs for up to a week and a half after exposure.

High-Risk Environments

Any setting where dogs are in close contact increases transmission risk:

  • Boarding kennels and doggy daycare
  • Grooming salons
  • Dog parks
  • Training classes
  • Animal shelters
  • Veterinary waiting rooms
  • Dog shows and competitions

Stress — from travel, new environments, or changes in routine — can temporarily suppress the immune system, making infection more likely in these settings.

Can Cats Get Kennel Cough?

Yes. Cats can be infected with Bordetella bronchiseptica, particularly in multi-pet households where an infected dog is present. Clinical signs in cats are usually mild upper respiratory symptoms, but infection is possible.

Signs of Kennel Cough

The hallmark sign is a dry, hacking, honking cough that often sounds like the dog is trying to clear something from their throat. Many owners describe it as a "goose honk" or assume the dog has something stuck in their airway.

Mild (Uncomplicated) CIRDC

  • Dry, persistent cough — often triggered by excitement, exercise, or pressure on the trachea (e.g., pulling on a collar)
  • Retching or gagging at the end of a coughing episode (sometimes producing white foam)
  • Otherwise normal — eating, drinking, and acting like themselves
  • Low-grade fever or no fever

Most uncomplicated cases resolve within 1–3 weeks without specific treatment.

Moderate to Severe CIRDC

  • Moist, productive cough
  • Nasal discharge (clear to mucopurulent)
  • Ocular discharge
  • Lethargy and decreased appetite
  • Fever (especially with canine influenza)
  • Labored breathing or increased respiratory rate

When It Becomes an Emergency

Seek immediate veterinary care if your dog shows:

  • Difficulty breathing or rapid, labored respirations
  • High fever (above 104°F / 40°C)
  • Productive cough with thick or bloody discharge
  • Severe lethargy or inability to stand
  • Bluish gums or tongue
  • Complete loss of appetite lasting more than 24 hours

These signs may indicate progression to pneumonia, which requires aggressive treatment and can be life-threatening, especially in puppies, senior dogs, and immunocompromised dogs.

How CIRDC Is Diagnosed

In most cases, kennel cough is a clinical diagnosis — your veterinarian will assess the history, vaccination status, clinical signs, and physical examination findings.

Key diagnostic elements:

  • History: Recent boarding, daycare, grooming, dog park visits, or exposure to other dogs with respiratory signs. Vaccination status matters — vaccinated dogs can still get CIRDC, but their signs are typically milder.
  • Physical exam: Auscultation (listening to the lungs and airways with a stethoscope), assessment of respiratory rate and effort, checking for nasal and ocular discharge, palpation of the trachea (which often triggers a cough in CIRDC dogs).
  • Fever check: Canine influenza and some bacterial infections commonly cause fever. The absence of fever does not rule out CIRDC.

When Further Diagnostics Are Needed

Additional testing may be recommended for dogs with severe signs, prolonged illness, or suspected pneumonia:

  • Thoracic radiographs (chest X-rays): To evaluate for pneumonia, airway patterns, and rule out other causes of coughing (heart disease, foreign body, tumor)
  • PCR respiratory panels: Identify specific viral and bacterial pathogens. These can be useful for outbreak management in facilities and for guiding antibiotic choices in severe cases. However, results can be difficult to interpret because some pathogens are carried by healthy dogs.
  • Complete blood count (CBC): To assess for infection and inflammation
  • Tracheal wash or bronchoalveolar lavage: In severe or unresponsive cases, to obtain samples for culture and sensitivity testing

Treatment

Treatment depends on disease severity, the suspected pathogen(s), and the individual dog's risk factors.

Mild, Uncomplicated Cases

Most dogs with mild CIRDC recover without specific treatment, similar to how humans recover from a common cold. Supportive care includes:

  • Rest. Limit exercise and excitement for 1–2 weeks. Activity triggers coughing episodes and delays recovery.
  • Harness instead of collar. Switching from a collar to a harness eliminates tracheal pressure that can trigger coughing.
  • Humidification. A humidifier or steam from a hot shower can help soothe irritated airways.
  • Soft food. If swallowing is uncomfortable, canned or softened food is easier on a sore throat.
  • Hydration. Ensure fresh water is always available.

Cough suppressants (antitussives) may be prescribed by a veterinarian in specific cases where the cough is severe enough to prevent rest and recovery. Do not give human cough medications to your dog — many contain ingredients that are toxic to dogs.

When Antibiotics Are Needed

Antibiotics are not effective against viruses, and most CIRDC cases have a viral component. However, antibiotics may be prescribed when:

  • A secondary bacterial infection is suspected (mucopurulent nasal discharge, fever, worsening signs)
  • The dog is in a high-risk environment (shelter, boarding facility) where outbreak control is important
  • Bordetella is suspected as a primary pathogen, particularly in dogs under six months
  • Signs persist beyond 10 days or are worsening

Common antibiotic choices include doxycycline (first-line for Bordetella) and amoxicillin-clavulanate (for secondary infections). Culture and sensitivity testing is ideal but not always practical. Antibiotic stewardship matters — unnecessary antibiotic use contributes to resistance and does not help viral infections. The ISCAID (International Society for Companion Animal Infectious Diseases) antimicrobial use guidelines recommend reserving antibiotics for cases with clear bacterial involvement.

Severe Cases and Pneumonia

Dogs that develop pneumonia require more aggressive treatment:

  • Hospitalization with intravenous antibiotics and fluid therapy
  • Oxygen supplementation
  • Nebulization and coupage (chest physiotherapy)
  • Nutritional support if the dog is not eating

Vaccines and Prevention

Vaccination is the most important preventive tool, but it is not a guarantee against infection. Think of CIRDC vaccines the way you think of the human flu vaccine — they may not prevent infection entirely, but they reduce the severity and duration of illness and lower the risk of complications like pneumonia.

Available Vaccines

Target Pathogen Vaccine Type Route Core / Lifestyle
Canine distemper Modified live or recombinant Injectable Core (part of DHPP/DA2PP)
Canine adenovirus 2 Modified live Injectable Core (part of DHPP/DA2PP)
Canine parainfluenza Modified live Injectable or intranasal Core (part of DHPP)
Bordetella bronchiseptica Avirulent live Intranasal or oral Lifestyle
Canine influenza H3N2 Killed Injectable Lifestyle
Canine influenza H3N8 Killed Injectable Lifestyle

The core vaccines (distemper, adenovirus, parainfluenza) are part of the standard DHPP/DA2PP series that most dogs receive as puppies and continue as adults. These cover three of the major CIRDC pathogens.

Bordetella and canine influenza vaccines are considered lifestyle vaccines, recommended for dogs at higher risk of exposure — those that board, attend daycare, visit groomers, or are regularly around other dogs.

Bordetella Vaccine Routes

  • Intranasal: Delivered as drops into the nose. Provides local mucosal immunity quickly — often within 48–72 hours. May cause mild, transient sneezing or nasal discharge.
  • Oral: Given by mouth. Also provides rapid mucosal immunity. A newer combined oral Bordetella + parainfluenza vaccine has demonstrated one-year duration of immunity in a 2025 study published in Frontiers in Veterinary Science.
  • Injectable: Given under the skin. Requires a booster 2–4 weeks after the initial dose for full immunity. May be preferred for dogs that resist nasal handling.

Many boarding and daycare facilities require Bordetella vaccination every 6–12 months. The specific requirement varies by facility.

Why Vaccinated Dogs Still Get Kennel Cough

This is one of the most common and frustrated questions from owners. There are several reasons:

  1. Multiple pathogens. The Bordetella vaccine only covers one bacterial cause. A vaccinated dog can still be infected by canine influenza, respiratory coronavirus, herpesvirus, pneumovirus, Mycoplasma, or other agents not included in vaccines.
  2. Incomplete protection. Even for the targeted pathogen, vaccines reduce severity rather than providing sterilizing immunity. A vaccinated dog exposed to Bordetella may develop mild signs rather than severe disease.
  3. Waning immunity. CIRDC vaccines do not provide long-lasting immunity the way core vaccines (distemper, parvo) do. Annual or semiannual boosters are needed.
  4. New or variant strains. Canine influenza viruses, in particular, can evolve, and vaccines may not cover every circulating strain.

Outbreak Management

If a case occurs in a boarding facility, shelter, or daycare:

  • Isolate the affected dog immediately
  • Disinfect surfaces, bowls, and equipment with appropriate disinfectants (quaternary ammonium compounds or bleach solutions are effective against most CIRDC pathogens)
  • Notify other owners
  • Consider prophylactic doxycycline for exposed dogs in high-risk settings (under veterinary guidance)
  • Review vaccination protocols for all dogs in the facility

Canine Influenza vs. Kennel Cough

Canine influenza (dog flu) is caused by specific influenza A viruses (H3N2 and H3N8) and is part of the CIRDC complex, but it is not the same as what most people call "kennel cough." Key differences:

  • Canine influenza more commonly causes fever, lethargy, and nasal discharge
  • H3N2 can spread to cats
  • Some dogs with CIV infection show no signs at all, while others develop severe pneumonia
  • The clinical overlap with other CIRDC pathogens makes laboratory testing important during outbreaks

If you are in an area with an active canine influenza outbreak, your veterinarian may recommend the canine influenza vaccine even if your dog does not normally need the Bordetella vaccine.

What to Ask Your Veterinarian

  • Does my dog need the Bordetella vaccine, or are the core vaccines sufficient for their lifestyle?
  • Should my dog also be vaccinated against canine influenza?
  • My dog was vaccinated and still got kennel cough — does this mean the vaccine did not work?
  • How long should I keep my dog away from other dogs while they are coughing?
  • When should I bring my dog back if the cough is not improving?
  • Is antibiotic treatment appropriate for my dog's case?

Sources

Topics
Vaccination & Infectious Disease
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