Kennel Cough

Dr. Lila Miller, D.V.M., ASPCA

Canine Infectious Tracheobronchitis
(Kennel Cough)


Canine Infectious Tracheobronchitis (ITB), more commonly known as kennel cough, is a highly contagious respiratory infection in dogs. When encountered in shelters, it is often seen as the canine equivalent of upper respiratory infections or URI in cats. It is common in dogs housed together in kennels, pet shops or shelters, hence its common name. It can infect all dogs, but affects puppies between the ages of 6 weeks and 6 months most severely. Kennel cough is characterized by the sudden appearance of a dry hacking cough in an otherwise healthy dog. It is a mild, self-limiting disease that usually gets better on its own without treatment. Despite the fact that most cases of kennel cough are not life threatening to the individual animal, many shelters consider kennel cough to be a serious threat to its canine residents because it spreads so readily. Shelters that have policies of not adopting out sick animals are compelled to either treat these coughing, but otherwise healthy dogs with antibiotics and cough syrups, making it expensive in terms of labor and medical costs, or euthanize them. The emotional costs to shelter personnel of euthanizing apparently healthy, adoptable animals that would otherwise get well on their own are immeasurable. Although kennel cough usually does not require treatment, it can result in more serious secondary complications such as bronchopneumonia that requires prolonged and expensive treatment. In these cases, it is sometimes confused with canine distemper, a much more deadly viral canine disease.

Cause

Kennel cough is seldom caused by a single agent, but by a combination of bacterial and viral agents. It is easier to deal with when caused by just one agent and in those cases, the disease appears much more likely to be self-limiting. However, because several agents are usually involved, dogs may cough for over two to three weeks, and sometimes as long as six. It is understandable why this is such a problem for a shelter. The causative or contributing agents are listed below:

Viral agents:
Canine Parainfluenza is the most common
Canine adenovirus 2 (CAV-2 or infectious canine hepatitis)
Canine adenovirus 1 (CAV-1 or infectious laryngotracheitis)

Bacterial agents:
Bordetella bronchiseptica
Other bacterial contributors to the severity of disease:
Streptococcus
Pasteurella
Pseudomonas
E. coli
Mycoplasma

Because they are the most prevalent causes of disease, the two organisms that will be the focus of this article will be Bordetella bronchiseptica bacteria and Parainfluenza virus.


Transmission

  • Kennel cough is most commonly seen in the summer and fall. The incubation period is generally 3- 10 days.
  • Animals as young as 2 weeks of age may contract the disease.
  • Transmission of both the Parainfluenza virus and Bordetella bacteria occurs primarily by dog to dog contact or contact with aerosolized droplets (airborne transmission)
  • Infection with Bordetella renders the respiratory tract more susceptible to infection by other opportunistic organisms.
  • It may take 3 months to clear the bacteria from the respiratory tract.
  • The virus may be shed for 2 weeks after infection.

Symptoms

There are two clinical syndromes associated with kennel cough, an uncomplicated and complicated one.
In general, dogs with uncomplicated kennel cough appear clinically normal except for a dry hacking cough that has been described as a “goose honk.” These dogs will also frequently retch up a white, frothy looking fluid. Gentle tracheal palpation will cause these dogs to cough. There is no fever, loss of appetite or lethargy. There may be a serous or clear nasal discharge.

Complicated cases exist that are characterized by fever, lethargy, loss of appetite and respiratory problems in addition to the cough. These dogs may also have an ocular and nasal discharge. They may be confused with cases of canine distemper.

Diagnosis

Diagnosis is usually accomplished by evaluation of the clinical signs and history. One of the most reliable methods of diagnosis is elicitation of a dry cough upon applying mild pressure to the trachea.

Treatment

  • Although treatment of uncomplicated kennel cough is usually not necessary, antibiotics are frequently prescribed to reduce the chances of development of a secondary bacterial infection and they may actually shorten the length of time the dog coughs. The most commonly used antibiotics include Clavamox, trimethoprim sulfonamide and doxycycline.
  • Short-term use (3-4 days) of low doses of steroids may lessen the severity of the inflammation of the trachea and hence the coughing.
  • Although they would seem to make sense, over the counter cough syrups seem to have little value. Cough suppressants may be used to reduce the coughing, especially if it keeps the owner and/or dog up at night, but their use should be limited. They should not be used at all in cases of pneumonia.
  • Dogs with kennel cough that are being walked should wear harnesses rather than collars to avoid putting pressure on the trachea. Dogs that get excited or exert pressure on their neck from pulling on a collar will cough.
  • Nebulizers utilizing sterile saline may be helpful. In cases where the animal is not responding to therapy, it may be necessary to add antibiotics or steroids to the solution.
  • Complicated cases may require fluids, antibiotics and other supportive treatment aimed at alleviating the symptoms.

Prevention

Injectable or intranasal vaccines to protect against ITB are available. In shelters where kennel cough is a real problem, an intranasal vaccine may be more useful. The maternal antibodies that often interfere with the effectiveness of injectable vaccines do not affect intranasal vaccines. They also stimulate a faster immune response, and can be used in animals as young as 2 weeks of age. The main drawback is they can cause coughing and a nasal discharge that cannot be easily differentiated from true clinical disease. Each shelter must decide for itself which product and vaccination protocol to use based on the cost, ability to administer the vaccine properly, ability to distinguish between clinical disease and vaccine induced disease, euthanasia policies, etc.

Disease control measures

  • Disinfect all cages and equipment with bleach, diluted 1:32 parts with water, chlorhexidine or benzalkonium.
  • Make certain the shelter has adequate ventilation of 12-20 air exchanges per hour.
  • Quarantine incoming dogs for 10 -14 days if possible, but if unable, make certain to isolate coughing dogs immediately.
  • Utilize foster care to get coughing dogs out of the facility. Foster caregivers should not have other dogs (or make certain they are properly vaccinated), small children, elderly or immune compromised people in their household- see Special Note.
  • Always wash hands after handling all animals. Most diseases are spread by contaminated objects (fomites) in addition to direct contact with an infected animal.
  • Launder all bedding with hot water, soap and bleach and discard all toys that do not go home with the dog.
  • Consider adopting out dogs with mild kennel cough with medication and full instructions to owners as to what to expect, how to treat and when to seek follow up veterinary care. (See special note below)

SPECIAL NOTE:
Bordetella is now considered to be a zoonotic disease. Although the risk of getting sick from contact with a pet is small, it must be considered. It is most easily transmitted to very young children, the elderly and people who are immune compromised. Cats may also be susceptible.


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