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Kennel Cough (Infectious Tracheobronchitis) – A Complete Medical Guide

Overview

Kennel cough, medically known as infectious tracheobronchitis, is a highly contagious respiratory disease that primarily affects dogs. It is comparable to the “common cold” in humans and is characterized by a harsh, hacking cough. The condition is most frequently seen in environments where many dogs congregate—kennels, dog parks, shelters, grooming facilities, and boarding homes—hence the name.

Who it affects: While any dog can contract kennel cough, puppies, senior dogs, and those with compromised immune systems are at highest risk. Small‑breed dogs (e.g., Dachshunds, Poodles) and working breeds (e.g., hounds, retrievers) appear over‑represented in case series, likely because of their frequent exposure to group housing.

Prevalence: In the United States, an estimated 1–5 % of boarded dogs develop kennel cough each year, translating to roughly 150,000–750,000 cases annually (American Veterinary Medical Association, 2023). Outbreaks are more common in the colder months when dogs are kept indoors and respiratory viruses thrive.

Symptoms

Symptoms can range from mild and self‑limiting to severe, especially when secondary bacterial infection occurs. The following list includes the most commonly reported signs, with a brief description of each:

• Dry, hacking cough – Often described as a “goose‑honk” sound; may be triggered by excitement, pressure on the trachea, or a change in temperature.
• Wet, productive cough – Indicates mucus production, often a sign of bacterial involvement.
• Rhinorrhea (nasal discharge) – Clear to pale yellow; can become mucoid if a secondary infection develops.
• Conjunctival discharge – Watery or serous; less common but may accompany viral forms.
• Fever – Low‑grade (101–103 °F / 38.3–39.4 °C); more typical with bacterial components.
• Lethargy – Decreased activity or interest in play.
• Loss of appetite – May be mild; can worsen if fever persists.
• Labored breathing or wheezing – Sign of lower airway involvement; warrants prompt veterinary assessment.
• Post‑cough vomiting – Due to intense abdominal muscle contraction during a cough bout.

Most cases resolve within 7–10 days, but some dogs may cough for several weeks. Persistent coughing beyond three weeks should be re‑evaluated for other conditions such as chronic bronchitis or pneumonia.

Causes and Risk Factors

Primary infectious agents

• Bordetella bronchiseptica – A gram‑negative bacterium considered the classic cause; transmitted via aerosolized droplets, direct contact, and contaminated surfaces.
• Canine parainfluenza virus (CPIV) – An RNA virus that damages the respiratory epithelium, facilitating bacterial colonisation.
• Canine adenovirus type‑2 (CAV‑2) – Causes mild respiratory signs and can act synergistically with Bordetella.
• Canine respiratory coronavirus (CRCoV) – Not to be confused with SARS‑CoV‑2; a separate coronavirus that predisposes to secondary infections.
• Other bacteria – Mycoplasma spp., Streptococcus zooepidemicus, and Pasteurella multocida are occasional co‑pathogens.

Risk factors

• Living or staying in high‑density dog environments (kennels, shelters, daycare).
• Puppies (< 6 months) and senior dogs (> 8 years) due to immature or waning immunity.
• Recent stressors: travel, vaccination, surgery, or changes in routine.
• Pre‑existing respiratory disease (e.g., chronic bronchitis, asthma).
• Immunosuppression from disease (e.g., Cushing’s) or medication (e.g., steroids).

Diagnosis

Diagnosis is largely clinical, supported by a focused history and physical examination. Because many respiratory pathogens produce similar signs, veterinarians may employ additional tests to confirm the causative agent or rule out complications.

History and Physical Exam

• Recent exposure to group housing or a known outbreak.
• Onset and character of cough, presence of fever, nasal/ocular discharge.
• Temperature, auscultation of lungs, and assessment of tracheal sensitivity.

Laboratory and Diagnostic Tests

• Tracheal or nasal swab PCR – Detects viral DNA/RNA (CPIV, CAV‑2, CRCoV) and Bordetella DNA; high sensitivity.
• Culture & sensitivity – Less common but useful for refractory cases to identify bacterial resistance patterns.
• Complete blood count (CBC) – May reveal neutrophilia (bacterial) or lymphocytosis (viral).
• Chest radiographs – Indicated if pneumonia is suspected; will show bronchial pattern or infiltrates.
• Bronchoscopy – Rarely required; reserved for chronic cough or when foreign bodies are a concern.

Treatment Options

Therapy aims to reduce coughing, eradicate bacterial infection (if present), and support the immune system. Most cases are mild and self‑limiting; however, treatment shortens illness duration and prevents spread.

Medications

• Antibiotics – Indicated when a bacterial component is confirmed or strongly suspected. First‑line choices include:
  • Doxycycline (5 mg/kg PO q12h for 7–10 days)
  • Enrofloxacin (5–10 mg/kg PO q24h)
  • Amoxicillin‑clavulanic acid (12.5–25 mg/kg PO q12h)
  Note: Antibiotic stewardship is essential; avoid use for purely viral cases.
• Cough suppressants – For severe, distressing cough:
  • Hydrocodone‑codeine combination (0.05–0.1 mg/kg PO q8‑12h)
  • Butorphanol (0.2–0.4 mg/kg PO q8‑12h) – less sedating.
  Use cautiously in brachycephalic breeds prone to airway obstruction.
• Bronchodilators – Albuterol inhaler (via spacer) for wheezing or bronchospasm.
• Anti‑inflammatories – NSAIDs (e.g., carprofen) for fever and discomfort; avoid in dogs with renal disease.
• Vaccines – Intranasal or oral Bordetella vaccine provides rapid, local immunity; core canine vaccines (DA2PP) contain CAV‑2, offering partial protection.

Procedural & Supportive Measures

• Humidified environment – Use a cool‑mist humidifier or steam bathroom sessions 2–3 times daily to soothe irritated airways.
• Isolation – Keep the infected dog separate from healthy dogs for at least 10 days after cough resolution to break transmission cycles.
• Fluid therapy – Oral electrolytes or sub‑Q fluids if the dog is dehydrated from fever or reduced water intake.

Lifestyle Adjustments

• Limit vigorous exercise while coughing; moderate leash walks are acceptable.
• Provide a calm, low‑stress environment; stress can suppress immunity.
• Ensure a balanced diet rich in antioxidants (e.g., blueberries, fish oil) to support immune function.

Living with Kennel Cough (Infectious Tracheobronchitis)

Even after the acute phase, caregivers can help their dogs recover fully and minimise recurrence.

• Monitor cough frequency – Keep a brief daily log; a decreasing trend signals improvement.
• Maintain good air quality – Avoid tobacco smoke, aerosol cleaners, and strong fragrances.
• Weight management – Overweight dogs have reduced lung capacity; a healthy body condition score (BCS 4–5/9) aids breathing.
• Regular veterinary check‑ups – Schedule a follow‑up 7–10 days after initial treatment to confirm resolution.
• Vaccination schedule – Keep Bordetella and core vaccines up‑to‑date, especially if frequent boarding or daycare is planned.

Prevention

Prevention is a combination of vaccination, hygiene, and management practices.

• Vaccination – Intranasal, oral, or injectable Bordetella vaccine provides 6–12 months of protection. Core vaccines protect against CAV‑2, and some multivalent products include CPIV.
• Environmental sanitation – Clean kennels, crates, and feeding bowls with a disinfectant effective against both bacteria and viruses (e.g., 1 % sodium hypochlorite).
• Quarantine new arrivals – Isolate new dogs for 14 days and observe for respiratory signs before mixing with resident dogs.
• Limit crowding – Ensure adequate ventilation and space (≥ 0.5 m² per dog) in boarding facilities.
• Hand hygiene – Staff and owners should wash hands with soap or use an alcohol‑based sanitizer before handling each dog.
• Stress reduction – Provide regular exercise, mental enrichment, and a predictable routine to keep the immune system robust.

Complications

While most dogs recover uneventfully, complications can arise, especially when the disease is severe or left untreated.

• Pneumonia – Bacterial superinfection can spread to the lung parenchyma, causing fever, increased respiratory effort, and infiltrates on radiographs.
• Chronic bronchitis – Persistent inflammation may lead to a lingering, dry cough that lasts months.
• Secondary otitis media – Extension of infection via the eustachian tube.
• Exacerbation of underlying heart disease – The added respiratory workload can precipitate heart failure in susceptible dogs.
• Spread to humans – While Bordetella bronchiseptica can infect immunocompromised people, transmission from dogs to healthy humans is rare.

When to Seek Emergency Care

References

1. American Veterinary Medical Association. “Kennel Cough (Infectious Tracheobronchitis).” AVMA.org, 2023.
2. Mayo Clinic. “Bordetella bronchiseptica infection in dogs.” MayoClinic.org, 2022.
3. Centers for Disease Control and Prevention. “Canine Infectious Respiratory Disease Complex.” CDC.gov, 2024.
4. National Institutes of Health – National Library of Medicine. “Parainfluenza virus infection in dogs.” PubMed, 2023.
5. Cleveland Clinic. “Cough in Dogs: Causes and Treatment.” ClevelandClinic.org, 2024.
6. World Health Organization. “One Health and Zoonotic Respiratory Infections.” WHO.int, 2023.

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