Kennel Cough (Canine Infectious Respiratory Disease)

Laurie Anne Walden, DVM

Kennel cough, the common term for canine infectious respiratory disease (or infectious tracheobronchitis), is a contagious disease that causes a hacking cough. The infection spreads quickly among dogs. Kennel cough is usually a mild illness, but some dogs develop more serious disease.
 
Causes
Many bacteria and viruses cause canine infectious respiratory disease. Most dogs with the disease are infected with more than 1 organism at the same time.[1,2] Some of the organisms involved are the following:

• Bordetella bronchiseptica (a bacterium)
• Canine parainfluenza virus
• Canine respiratory coronavirus
• Mycoplasma species
• Streptococcus zooepidemicus
• Canine adenovirus type 2
• Canine distemper virus
• Canine influenza virus

 
Risk Factors
Not all dogs get sick after being exposed to an agent that can cause respiratory disease. Some of these organisms are unlikely to cause illness on their own but can cause symptoms when combined with other organisms.[3] Whether a dog develops respiratory disease is also affected by environmental factors (such as crowding and poor ventilation) and the dog’s immune system.
 
Kennel cough spreads through respiratory secretions from an infected dog. Dogs with no symptoms at all can spread the infection. Droplets containing bacteria or viruses become airborne after a dog coughs or sneezes and are deposited on surfaces, water bowls, toys, and other objects. The higher the number of dogs housed together, the higher the chance of a dog coming into contact with infected respiratory secretions.
 
Crowding increases stress, which reduces a dog’s protective immune response against infection. Some infectious agents can hinder the immune response, making infection with additional organisms more likely.
 
Bordetella bronchiseptica can infect cats and possibly humans. Infection in humans is probably of most concern in people with impaired immune function.
 
Symptoms
Because of the variety of organisms and differences in individual dogs, symptoms can vary. Typical symptoms of the mild form of disease include the following:

• Hacking, dry cough (often described as sounding like hacking up a hairball)
• Sneezing
• Normal or slightly decreased appetite
• Normal or slightly decreased activity level
• Improvement in symptoms after a week or two[4]

 
Some dogs, especially young puppies, elderly dogs, and dogs with poor immune function, develop more severe bronchitis and pneumonia. These dogs have more serious symptoms:

• Fever
• Loss of appetite
• Listlessness
• Moist cough
• Mucus/pus discharge from the nose

 
Diagnosis
For dogs with mild disease, kennel cough is usually presumed from physical examination findings and history of exposure to other dogs. Dogs with a persistent cough or signs of more serious disease need diagnostic testing, which can include chest radiographs, blood tests, and (in some cases) tests to identify the organisms involved.
 
Treatment
Treatment decisions are based on the severity of the illness and the dog’s environment. Mild cases of kennel cough often resolve on their own, so dogs with mild disease might need only supportive care (good nutrition, limited activity, and a warm place to rest indoors). Some dogs benefit from treatment with an antibiotic active against Bordetella. Most dogs with kennel cough should not receive cough suppressants. Dogs with more severe disease need more intensive treatment. The treatment for dogs in an environment with a high risk of disease spread (like a shelter) may be different from the treatment chosen for a pet living at home.
 
Prevention
Vaccines help control canine infectious respiratory disease. No single vaccine can entirely prevent kennel cough, but vaccinations protect dogs against some of the organisms and reduce the severity and spread of disease.
 
A combination vaccine including canine distemper virus, canine adenovirus type 2, and sometimes canine parainfluenza virus is recommended for all dogs.[5] Puppies receive this vaccine as part of the puppy vaccine series. Adult dogs should have booster vaccinations (or antibody titer tests).
 
A vaccine against Bordetella bronchiseptica, sometimes also including canine parainfluenza virus, is recommended for dogs whose lifestyle puts them at risk for infection. The Bordetella vaccine is given in the nose, in the mouth, or by injection, depending on the formulation. Vaccines against canine influenza virus are also available. The decision to give a dog Bordetella and flu vaccines depends on the dog’s lifestyle and possibly on geographic area. Talk to your veterinarian about these vaccines if your dog goes to boarding kennels, doggie daycare, dog parks, dog shows, groomers, shelters, or other areas where dogs gather.
 
Because infectious respiratory disease is so contagious, dogs with symptoms should be kept away from other dogs as much as possible. Washing hands, bowls, dog toys, and clothing can reduce the risk of spreading the infection to other dogs.

References
1. Schulz BS, Kurz S, Weber K, Balzer HJ, Hartmann K. Detection of respiratory viruses and Bordetella bronchiseptica in dogs with acute respiratory tract infections. Vet J. 2014;201(3):365-369.
2. Hurley K, Aziz C. Canine infectious respiratory disease complex (CIRDC) - diagnosis and treatment; prevention and management. Pacific Veterinary Conference 2015. Veterinary Information Network website. https://www.vin.com/doc/?id=6789809. Accessed December 6, 2019.
3. Canine infectious respiratory disease complex (CIRDC, a.k.a. “kennel cough”). University of Wisconsin-Madison Shelter Medicine website. https://www.uwsheltermedicine.com/library/resources/canine-infectious-respiratory-disease-complex-a-k-a-kennel-cough. Published July 2015. Accessed December 6, 2019.
4. Kuehn NF. Tracheobronchitis in small animals. Merck Veterinary Manual website. https://www.merckvetmanual.com/respiratory-system/respiratory-diseases-of-small-animals/tracheobronchitis-in-small-animals. Accessed December 6, 2019.
5. 2017 AAHA canine vaccination guidelines. American Animal Hospital Association website. https://www.aaha.org/aaha-guidelines/vaccination-canine-configuration/vaccination-canine/. Published September 7, 2017. Updated February 3, 2018. Accessed December 6, 2019.
 
Photo by Hannah Lim

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