Animal Health
"Beyond Kennel Cough"
Vector of a dog coughing
AN OVERVIEW OF CANINE INFECTIOUS RESPIRATORY DISEASE COMPLEX
By Kate Boatright, VMD
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nfectious respiratory diseases have the potential to spread rapidly in a boarding environment with multiple dogs housed closely together. This is why Kennel Cough is so well known among pet owners, and it can be a major concern for boarding and daycare facilities.

Kennel Cough is now understood to involve multiple infectious organisms that include a combination of viruses and bacteria. Because of this, the disease is often referred to as “Canine Infectious Respiratory Disease Complex (CIRDC).” Understanding the organisms that can contribute to the infection, how they can be prevented and what to do with a coughing dog in your facility will help keep your boarders safe.

Understanding the Infection
In mild cases, coughing is the most common clinical sign. The harsh cough is often nonproductive and may resemble the sound of a goose honk. Sometimes coughing fits can occur. Other signs of upper respiratory infection may be present, including nasal discharge, sneezing and ocular (eye) discharge. Some dogs may also be lethargic and have a decreased appetite.

In certain cases, especially very young dogs or those with other ongoing diseases, the infection can progress to a lower airway infection and cause pneumonia. These cases often have a fever and tend to be more lethargic and inappetent in addition to the clinical signs seen with mild cases. Brachycephalic dogs (short-snouted breeds like Bulldogs and Boston Terriers) are more at risk for pneumonia.

Many pathogens are involved in CIRDC, and clinical disease is often caused by a combination of these organisms. Bordetella bronchiseptica is a bacteria that is one of the most well-known pathogens in CIRDC. Historically, the terms “Kennel Cough” and “Bordetella” have been used interchangeably, as it is thought to be a primary organism involved in clinical disease.

One virus that contributes to CIRDC is canine influenza virus. Canine influenza virus is a growing threat in some regions of the country and often occurs in localized outbreaks. It was first reported in Florida in 2004 in racing Greyhounds. Several outbreaks have occurred since, including one in Chicago in 2015, and in several locations nationwide in 2022 and 2023. Dogs infected with this virus are at higher risk of developing pneumonia which, in some cases, can be deadly.

Vector of bacteria filled air being blown across dog's snout
The diagnosis of CIRDC is usually made based on clinical signs and a history of recent boarding, grooming or contact with new dogs.
Additional viruses that can be involved in infection include distemper, adenovirus type 2, parainfluenza, herpesvirus and coronavirus. Other bacterial organisms that can contribute to disease include Mycoplasma and Streptococcus equi subsp zooepidemcus.

The diagnosis of CIRDC is usually made based on clinical signs and a history of recent boarding, grooming or contact with new dogs. Diagnostic testing will depend on the severity of illness and may include bloodwork and chest x-rays. Testing for specific organisms can be difficult and is rarely pursued, except in severe disease or outbreak situations.

Treatment is similar regardless of the specific organisms involved. Cough suppressants may be prescribed to help patient comfort. In most cases of mild infection, the cough will resolve within a few weeks, even without treatment. Antibiotics may be prescribed by a veterinarian if a bacterial component is suspected. For pneumonia cases, hospitalization is often required to provide oxygen support in the most serious phases of the disease.

Preventing Infection through Vaccination
Vaccination is an essential component of prevention. The following vaccines are available:

  • DA2PP vaccine (commonly referred to as “distemper vaccine”) provides immunity against distemper, adenovirus type 2 and parainfluenza. It is available as an injectable vaccine that is given every one to three years after an initial booster series, depending on the product used.
  • Bordetella vaccine provides immunity against Bordetella bronchiseptica. There are a variety of vaccines available, and some also vaccinate against adenovirus and parainfluenza. The vaccine may be given intranasally, orally or by injection. Studies are unclear about which vaccine route is best, though intranasal vaccination is preferred by many, as it helps develop immunity at the site where the Bordetella organism will enter the body. This vaccine is typically given once a year.
  • Canine influenza vaccine is available; however, there are fewer manufacturers for this vaccine, making availability limited, especially in times of outbreaks. There are two strains of canine influenza recognized, and most vaccines include both.
Vector of vaccination needle
Timing of vaccination is important to consider, as it takes time for the immune system to respond to vaccines. Patients are not immediately immune following vaccine administration.
One of the hardest parts of reducing exposure is that most infected dogs will shed bacteria or virus prior to showing signs of illness. In other words, infected dogs are contagious before they show they are sick. This is why vaccination is especially important, as it can reduce shedding of organisms.
Timing of vaccination is important to consider, as it takes time for the immune system to respond to vaccines. Patients are not immediately immune following vaccine administration. Ideally, vaccines should be given at least two weeks prior to boarding. For Bordetella, dogs should be vaccinated at least five days prior to entering your facility to have adequate protection during their stay. For dogs that were vaccinated immediately before entering the facility, consider housing them away from other dogs when possible.

Vaccination for Bordetella and canine influenza do not provide complete immunity. Instead, the vaccine works to decrease the severity of symptoms and shedding of infectious organisms. This means that preventing exposure to infectious organisms is another essential component of prevention.

Preventing Infection by Reducing Exposure
Most organisms are spread through multiple routes, including direct contact between dogs and aerosol transmission. Many can also survive on surfaces of enclosures, food bowls, toys, clothing and human skin for hours or even days, creating a risk for indirect transmission. For example, canine influenza virus can survive on hands for 12 hours, clothing for 24 hours and other fomites for 48 hours. Hand-washing between handling dogs and limiting shared spaces and toys or other items are important steps in reducing communicable diseases.

One of the hardest parts of reducing exposure is that most infected dogs will shed bacteria or virus prior to showing signs of illness. In other words, infected dogs are contagious before they show they are sick. This is why vaccination is especially important, as it can reduce shedding of organisms. Most dogs will continue to shed infectious organisms for at least a week after infection. Some organisms, such as Bordetella, can be shed for several months after infection. A dog with a recent history of CIRDC should be isolated from other dogs, even after coughing resolves, to prevent continued spread of disease.

What to Do with a Coughing Dog
If a dog begins coughing while staying in your facility, it should be isolated from others until a cause for the cough can be determined. There are many causes of coughing that are not infectious, such as partial airway obstructions, collapsing trachea and congestive heart failure. If a pet seems to be in distress, it should be evaluated by a veterinarian on an emergency basis.

For cases where an infectious cause is suspected, the ideal isolation would be in a separate area from the main boarding area. If this is not possible, keep the dog a minimum of 25 feet away from others. Anyone who handles the dog should wear gloves, shoe covers and ideally a gown. They should thoroughly wash their hands prior to handling other dogs and clean their shoes with a disinfecting solution prior to leaving the area where the infected dog is housed. The dog’s original enclosure should be cleaned thoroughly with a dilute bleach solution and all bedding, food and water bowls, leashes and other items that came in contact with the dog should be sterilized. Also consider isolating any dogs who were in close contact with the infected dog and monitoring them closely for signs of illness.

In the event that your facility experiences a respiratory disease outbreak, contact your veterinarian to discuss testing infected dogs to determine which organisms are involved in the infection. This will help the veterinarian to decide the best treatment plan and make recommendations for how to eliminate the infection from your environment.