Kennel Cough

TL;DR. Kennel cough is a highly contagious but usually mild respiratory infection in dogs that causes a harsh, hacking cough and typically resolves on its own within two weeks.

Most cases of kennel cough are mild and can be managed at home with rest and supportive care.

What is it?

Kennel cough, known scientifically as canine infectious tracheobronchitis or canine infectious respiratory disease complex (CIRDC), is a highly contagious, acute respiratory disease that affects dogs of all ages. The condition is characterized by inflammation of the trachea (windpipe) and bronchi (the larger airways leading into the lungs). It is not caused by a single pathogen; rather, it is a complex infection that can involve several different viruses and bacteria working individually or together to compromise the dog's respiratory defenses.

When a dog inhales these infectious particles, the pathogens attach to the lining of the respiratory tract, damaging the protective cells and causing localized inflammation. This inflammation makes the airways highly sensitive, leading to the characteristic dry, hacking cough that many owners describe as sounding like a goose honk. While the sound of the cough can be distressing to owners, the disease is typically self-limiting in healthy adult dogs, meaning it will run its course and resolve without major medical intervention.

Understanding this disease is crucial for pet owners because of how easily it spreads. In environments where dogs congregate, a single coughing dog can rapidly infect dozens of others. While most cases remain mild and uncomplicated, there is always a risk that the infection can progress to secondary bacterial pneumonia, particularly in puppies, senior dogs, or dogs with compromised immune systems.

Causes & risk factors

Kennel cough is caused by a variety of viral and bacterial pathogens. Common culprits include the bacterium Bordetella bronchiseptica, canine parainfluenza virus, canine adenovirus type 2, and canine influenza virus. According to a leading veterinary internal medicine reference:

"Most dogs infected with canine influenza virus present with signs of canine infectious tracheobronchitis, often with concurrent nasal discharge..." [1]

The primary risk factor for contracting kennel cough is exposure to areas where multiple dogs gather. The pathogens are highly contagious and spread through airborne droplets generated by coughing or sneezing, direct nose-to-nose contact, or contaminated surfaces (such as shared water bowls, toys, or kennel walls).

A dog's history often reveals a clear window of exposure. As noted in veterinary literature, a history of:

"...boarding, hospitalization, or exposure to a puppy or dog that has similar signs is common. Puppies recently obtained from pet stores, kennels, or shelters have often been exposed to the pathogens." [4]

The incubation period is typically short, with clinical signs developing within 2 to 14 days after exposure. There are no known breed predispositions for kennel cough; any dog, regardless of breed, size, or age, can contract the infection if exposed. However, dogs with pre-existing airway abnormalities (such as a collapsing trachea) or those that are immunologically compromised are at a higher risk for developing more severe or complicated forms of the disease.

Signs to watch for

The clinical signs of kennel cough are usually localized to the upper respiratory tract. In uncomplicated cases, dogs remain bright, alert, and active, with a normal appetite, despite their respiratory symptoms.

Key symptoms to watch for include:

• Cough (cardinal): A sudden, harsh, dry, hacking cough that often sounds like a honking goose. This cough can occur in paroxysms (sudden outbursts) and may be worsened by excitement, exercise, or pressure on the windpipe.
• Cough induced by tracheal palpation (common): Gentle pressure applied to the dog's windpipe during an exam easily triggers a coughing fit.
• Gagging (occasional): The cough often ends with a gagging or retching motion, which can lead owners to believe the dog is trying to vomit or has something caught in its throat.
• Retching (occasional): Similar to gagging, this is a spasmodic effort to clear the throat of mucus.
• Nasal discharge (occasional): A mild, watery, or slightly mucoid discharge from the nose may be present, particularly if canine influenza or other specific viral agents are involved.

Using a harness instead of a collar prevents pressure on the sensitive, inflamed trachea.

While these signs are typical of uncomplicated kennel cough, owners must watch closely for signs of progression. If a dog becomes lethargic, loses its appetite, develops a fever, or shows rapid or labored breathing, the disease may have progressed to secondary bacterial pneumonia. This is a serious, potentially life-threatening complication that requires immediate veterinary attention.

How vets diagnose it

In many cases, a veterinarian will make a presumptive diagnosis of kennel cough based on the dog's clinical signs and a recent history of exposure to other dogs (such as boarding, training classes, or visits to a dog park).

During the physical examination, your vet will perform tracheal palpation. By gently pressing on the trachea, they will attempt to elicit the characteristic cough. If the dog is otherwise healthy, active, and has a clear chest on auscultation (listening with a stethoscope), further diagnostic testing is often unnecessary for a first-time, mild case.

However, if the dog is showing signs of systemic illness, or if the cough does not resolve within two weeks, your vet will recommend diagnostic tests to rule out more serious conditions like pneumonia, collapsing trachea, or heart disease. These tests may include:

• Thoracic radiographs (chest X-rays): This is the most important test to determine if the infection has spread to the lungs and caused secondary pneumonia.
• Complete blood count (CBC): A blood test to evaluate white blood cell levels, which can indicate the severity of the inflammatory or infectious process.
• Tracheal wash fluid analysis: This procedure involves flushing a small amount of sterile saline into the trachea and then suctioning it back out. The recovered fluid contains cells from the airway lining, which are analyzed under a microscope to identify the types of inflammatory cells present.
• Bacterial culture of tracheal wash fluid: The fluid obtained from a tracheal wash can be cultured in a laboratory to grow and identify any bacterial pathogens, such as Bordetella bronchiseptica, and determine which antibiotics are most effective.
• Polymerase chain reaction (PCR) testing: Swabs from the nose or throat can be analyzed using PCR to detect the genetic material of specific respiratory viruses and bacteria, providing a rapid identification of the underlying pathogens.
• Paired serology: This involves taking two blood samples—one during the acute phase of the illness and another two to four weeks later. A significant rise in antibody levels between the two samples confirms an active infection by a specific pathogen, such as canine influenza.

Treatment options

For uncomplicated cases of kennel cough, the disease is self-limiting and typically resolves on its own. Interestingly, routine medical intervention with drugs is often not indicated for these mild cases. A leading veterinary internal medicine textbook states:

"No field studies have demonstrated any benefit of steroid therapy, either alone or in combination with antibiotics. If clinical signs have not resolved within 2 weeks, further diagnostic evaluation is indicated." [3]

Because of this, treatment for uncomplicated kennel cough focuses primarily on supportive care and environmental management:

• Rest and isolation: Strict rest is essential. Exercise can irritate the airways and trigger coughing fits. Additionally, because the disease is highly contagious, infected dogs must be strictly isolated from other dogs for at least two weeks after the cough resolves to prevent spreading the infection.
• Airway protection: Avoid using collars during this time. Any pulling on a leash attached to a collar puts direct pressure on the inflamed trachea, worsening the cough and inflammation. Switch to a chest harness instead.
• Humidification: Exposing the dog to warm, humid air (such as keeping them in the bathroom while you take a hot shower) can help soothe irritated airways and loosen secretions.
• Avoid unnecessary medications: Unless prescribed by your veterinarian, avoid giving over-the-counter cough suppressants or human medications, as these can be harmful or mask worsening symptoms.

If the disease progresses to a complicated case involving secondary bacterial pneumonia, your vet will prescribe targeted antibiotic therapy based on culture results, along with more intensive supportive care, which may require hospitalization.

Prognosis

The prognosis for recovery from uncomplicated kennel cough is excellent. Most dogs recover completely within approximately two weeks without any long-term consequences.

As noted in veterinary literature:

"The prognosis for recovery from uncomplicated infectious tracheobronchitis is excellent..." [3]

If the cough persists beyond two weeks, it is not necessarily a sign of a poor prognosis, but it does indicate that further diagnostic testing is required to rule out secondary bacterial pneumonia or other underlying airway diseases.

Prevention

Preventing kennel cough involves a combination of vaccination and sensible lifestyle management. Vaccines are available for several of the pathogens associated with the disease, including Bordetella bronchiseptica, canine parainfluenza virus, and canine influenza virus. These vaccines can be administered intranasally (drops in the nose), orally, or via injection.

However, owners must understand the limitations of these vaccines. As a leading veterinary reference explains:

"Vaccines do not prevent infection, and none is completely effective in preventing signs, just as the seasonal influenza vaccine does not prevent all infections or signs. People and dogs are more likely to become seriously ill if they are compromised in some way before infection..." [2]

While vaccines may not entirely prevent a dog from catching kennel cough, they are highly effective at reducing the severity of the clinical signs and lowering the risk of the infection progressing to life-threatening pneumonia.

In addition to vaccination, you can reduce your dog's risk by:

• Avoiding high-density dog areas (like boarding kennels, doggy daycares, and busy dog parks) during known local outbreaks.
• Ensuring any facility you board your dog at requires up-to-date vaccinations for all canine guests.
• Keeping your dog's immune system strong through proper nutrition, regular veterinary care, and minimizing stress.

When to call your vet

While kennel cough is often a mild illness, you should consult your veterinarian if you suspect your dog has contracted it. You should contact your vet immediately if you notice any of the following warning signs:

• The cough lasts for more than two weeks without improvement.
• Your dog becomes lethargic, depressed, or unwilling to interact.
• Your dog loses interest in food or stops drinking water.
• You notice a thick, green, or yellow discharge from the nose or eyes.
• Your dog exhibits rapid breathing, labored breathing, or respiratory distress (this is an emergency).
• Your dog has a pre-existing health condition, is very young (a puppy), or is senior, as they are at a much higher risk for complications.

Sources

• Internal Medicine, 5th Edition, pages 331, 332, 333.