Kennel cough, also known as infectious tracheobronchitis, is a common respiratory illness in dogs characterized by a distinct, harsh, hacking cough. Many owners describe the sound as if their dog has something stuck in its throat. While this condition can be mild and resolve on its own within a week or two, it can also escalate to life-threatening pneumonia, depending on the specific infectious agents involved and the dog’s overall health and immune status. Uncomplicated cases typically present with frequent coughing fits but the dog remains otherwise active and normal, without fever or lethargy.
This complex respiratory infection is rarely caused by a single agent. Instead, it’s usually a combination of various bacteria and viruses. The most common culprits include Bordetella Bronchiseptica (a bacterium), parainfluenza virus, and adenovirus type 2. Other contributing factors can involve canine distemper virus, canine herpesvirus (especially in very young puppies), Mycoplasma Canis (a unique single-cell organism), and canine reovirus. A classic combination for milder kennel cough involves parainfluenza or adenovirus type 2 alongside Bordetella Bronchiseptica. However, infections involving canine distemper virus or canine influenza virus are more likely to progress to pneumonia, though pneumonia can occur in any dog, particularly if they are very young, stressed, or debilitated.
Understanding Coughing Sounds in Dogs
Dogs can produce a variety of respiratory sounds, and while a cough is usually recognizable, it’s important to distinguish it from a reverse sneeze. A reverse sneeze is often mistaken for coughing, choking, gagging, or difficulty breathing. In reality, it’s caused by a post-nasal drip or throat irritation and is considered normal, especially in smaller breeds. It typically doesn’t require veterinary attention unless it becomes excessive. A true cough can be dry or productive, meaning it’s followed by a gagging or swallowing motion, sometimes producing foamy mucus.
How Infection Spreads
Infected dogs shed infectious bacteria and viruses through their respiratory secretions. These microscopic particles can become aerosolized and inhaled by healthy dogs, leading to transmission. Close living conditions and poor ventilation significantly increase the risk of spread, but the viruses and bacteria can also transfer via shared toys, food bowls, and other objects.
The dog’s respiratory tract has natural defense mechanisms, the most crucial being the mucociliary escalator. This system involves tiny, hair-like structures called cilia lining the respiratory tract, covered by a layer of mucus. The cilia beat in a coordinated manner, moving the mucus layer upwards, trapping debris and infectious agents, and carrying them towards the throat to be coughed up or swallowed. This escalator is vital for clearing the airways, but it can be compromised by various factors, including shipping stress, crowding, heavy dust exposure, cigarette smoke, cold temperatures, poor ventilation, and the infectious agents themselves. When this system is impaired, bacteria, particularly Bordetella Bronchiseptica, can travel unimpeded down the airways.
Bordetella Bronchiseptica has specific mechanisms to evade defenses: it can attach directly to cilia, hindering their movement within hours of contact, and it secretes substances that disable immune cells designed to fight bacteria. Because Bordetella is often accompanied by other infectious agents, kennel cough is best understood as a complex of infections rather than a single disease.
Dogs typically contract kennel cough in crowded environments with poor air circulation and warm temperatures, such as boarding kennels, vaccination clinics, obedience classes, dog parks, animal shelters, veterinary waiting rooms, or grooming facilities. In most cases, acute coughing in dogs is attributed to infectious causes, generally some form of kennel cough.
The incubation period for kennel cough is between 2 to 14 days, and dogs are usually sick for one to two weeks. Infected dogs can shed Bordetella organisms for up to 2-3 months post-infection.
Diagnosis and Treatment
Diagnosis is typically based on the dog’s history of exposure to other dogs within the relevant timeframe, coupled with examination findings – specifically, a coughing dog that otherwise appears healthy. Radiographs can reveal signs of bronchitis and are essential for detecting any complicating pneumonia. Recently, PCR (polymerase chain reaction) testing has become available, allowing for the detection of multiple kennel cough agents from a single swab, which can help guide treatment decisions.
While most kennel cough cases resolve on their own, antibiotics are often prescribed to target Bordetella Bronchiseptica and potentially hasten recovery. Cough suppressants may also be used to provide comfort during the natural course of the illness, and sometimes antibiotics and cough suppressants are used in combination.
Prevention Through Vaccination
Vaccinations are available to protect against Bordetella bronchiseptica, canine adenovirus type 2, canine parainfluenza virus, canine distemper, and canine influenza. Infections with other components of the kennel cough complex cannot be prevented by vaccination. The vaccine for adenovirus type 2, parainfluenza, and canine distemper is often part of the standard puppy vaccination series (DHPP). For Bordetella bronchiseptica, vaccination can be administered either as an injectable or a nasal immunization. There is some debate about which method offers superior protection, or if a combination is best.
The intranasal vaccine can be given as early as 3 weeks of age, providing immunity for about 12 to 13 months. A key advantage is that it stimulates local immunity directly at the site of potential infection. Solid immunity is typically achieved within four days of intranasal vaccination, making it ideal to administer at least four days before anticipated exposure. Some dogs may experience mild sneezing or nasal discharge for a week following intranasal vaccination, which usually resolves on its own. Nasal vaccines often provide faster immunity compared to injectable versions and frequently include protection against parainfluenza and adenovirus type 2.
Injectable vaccination is a good option for dogs that may be aggressive if their muzzle is handled. For puppies, two doses of the injectable vaccine, given about a month apart and after 4 months of age, provide robust systemic immunity. Annual boosters are generally recommended. Some dogs may develop a small lump at the injection site, which typically resolves without intervention.
It’s important to note that vaccination is not effective if a dog is already incubating kennel cough. If boarding is planned, and more than six months have passed since the last booster, it’s advisable to administer the vaccine at least five days prior to boarding. While Bordetella bronchiseptica vaccination may not completely prevent infection, it can significantly minimize symptom severity. Dogs that have recovered from Bordetella bronchiseptica infection generally have immunity for 6 to 12 months.
When Kennel Cough Doesn’t Improve
Kennel cough is typically a self-limiting illness and should show at least partial improvement within a week of treatment. If no improvement is observed during this period, a follow-up veterinary examination, potentially including chest radiographs, is recommended. A lack of improvement may indicate an underlying condition, such as pre-existing collapsing trachea that has been exacerbated, or the progression to pneumonia. Canine influenza, a highly contagious respiratory infection that causes fever and pneumonia, can also initially present with symptoms similar to routine kennel cough.
If you have concerns about your dog’s cough, it is always best to consult with your veterinarian for an accurate diagnosis and appropriate treatment plan.
