Canine Infectious Respiratory Disease Complex (CIRDC)

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Canine Infectious Respiratory Disease Complex (CIRDC)

Canine Infectious Respiratory Disease Complex (CIRDC) is seen frequently, as it easily and quickly spreads from dog to dog. This occurs most commonly in crowded circumstances such as boarding, doggie daycare, dog parks, and dog shows. CIRDC is seen as often in animal shelters as the common cold is seen in human daycare centers. In this article you will learn more about the specific pathogens or disease-causing organisms that lead to CIRDC, resulting in the coughing symptoms seen in dogs.

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What is CIRDC and how is it spread?

CIRDC infections occur in a single dog, in localized groups of dogs, or larger areas such as a county, state, or even a national outbreak. Dogs can quickly spread CIRDC without any outward symptoms, making it challenging to stop the spread in settings with multiple dogs such as a kennel.

It’s important to understand that vaccines help decrease the severity of the illness and decrease the amount of shedding of some of the infectious bacteria and viruses which contribute to CIRDC.

Each CIRDC bacteria/virus can spread the disease depending on how long the organism remains infectious in the environment and depending on the immunity or health of the local community of dogs. The CIRDC bacteria/viruses’ ability to spread disease varies by the amount of time they stay infectious in the environment through things such as contaminated surfaces of dog kennels, people’s hands, etc. For example, the canine influenza virus is only infectious for a few hours to days in contrast to canine adenovirus 2 which remains infectious for weeks or months.

Most cases of CIRDC are mild and dogs often only need supportive care and a cough suppressant to improve. Note that you should never give your dog any medication unless directed by your vet. Dogs that have a weakened or immature immune system, such as puppies or senior dogs with concurrent health problems, can develop severe disease and sometimes result in death.

What causes CIRDC in dogs?

Currently, veterinarians have identified at least 9 different bacteria and viruses contributing to CIRDC (often called kennel cough or canine cough). Dogs often have more than one bacteria or virus causing their symptoms.

The most common viral causes of CIRDC include:

● Canine adenovirus 2

● Canine distemper virus

● Canine influenza viruses

● Canine herpesvirus

● Canine parainfluenza virus

● Respiratory coronavirus (different from canine enteric coronavirus and not linked to human coronavirus or COVID19)

● Pneumovirus

The most common bacterial causes of CIRDC include:

● Bordatella bronchiseptica

● Streptococcus equi subspecies zooepidemicus

● Mycoplasma spp.

Symptoms of Canine Infectious Respiratory Disease Complex

Signs and symptoms of CIRDC involve not only the trachea but also show up as sneezing and discharge from the eyes and nose. More severe cases can cause lung disease such as pneumonia. CIRDC has a complicated origin and many different secondary bacteria likely cause more severe illness in some dogs.

Spread and Risk of Infection from Dog to Dog

Usually, dogs that shed CIRDC organisms have symptoms of the disease. In some cases, dogs shed the organism before showing signs of illness and some dogs are contagious yet never show any symptoms.

Infection is spread by direct contact (dog-to-dog), through the air by inhaling an infected dog’s cough or sneeze droplets, and by licking things that have been contaminated by an infected dog’s cough, sneeze, or discharge from the eyes or nose (from people, toys, floor, bedding, etc.).

Managing CIRDC Outbreaks

Dogs diagnosed with CIRDC or suspected of having the disease should be isolated or kept physically away from other dogs to prevent spreading the disease until cleared by their vet.


Most of the CIRDC organisms can be killed by ordinary disinfectants. For more resistant organisms such as Adenovirus-2, use ordinary household bleach diluted at a ratio of 1:32 (½ cup of bleach mixed with 1 gallon of water), calcium hypochlorite, sodium dichloroisocyanurate, potassium peroxymonosulfate, and accelerated hydrogen peroxide to inactivate the virus.

Wet or moist environments can contribute to the infective organisms remaining in the environment, therefore, contaminated areas should be washed and dried thoroughly.

Can people or other pets get CIRDC?

The answer is yes, but it’s very uncommon and most likely to happen in immunocompromised people (for example an HIV patient or someone undergoing chemotherapy).

The organism, Bordatella bronchiseptica, can spread from dogs to people. Immunocompromised individuals should take additional precautions with dogs diagnosed or suspected of having CIRDC by avoiding contact and practicing good hygiene measures.

It has been reported that, in rare cases, immunocompromised individuals have been infected and gotten sick with B. bronchiseptica after their dog was vaccinated with the modified live B. bronchiseptica vaccine. As a precaution, it’s recommended that dogs of immunocompromised individuals receive the killed form of the B. bronchiseptica vaccine.

If you or someone in your family is severely immunocompromised, talk to your physician regarding your concerns about CIRDC.

B. bronchiseptica and Influenza (H3N2) have been reported to infect cats.

How is CIRDC diagnosed in dogs?

For individual cases, diagnosing and treating CIRDC is often determined based on a history of possible exposure (such as recently boarding at a dog kennel or being around other dogs at a dog park). Specific testing should happen if an outbreak occurs in a geographical area, if symptomatic dogs are not responding to supportive care, are showing more severe signs, or if there is concern about transmission to people. Knowing which organism(s) is causing the CIRDC in these cases will help determine more effective treatment and help manage the outbreak to prevent further spread.

Current Diagnostic Testing Options

● Culture and sensitivity

● Serology

● Virus isolation

● PCR (Polymerase chain reaction)

● Histopathology

● Necropsy (the most accurate and definitive diagnostic tool which should be used in outbreaks where dogs have died or are euthanized from suspected CIRDC).

Preventing CIRDC in Dogs

For dogs at risk of exposure to CIRDC such as those who frequent doggy daycare, dog parks, or boarding facilities, vaccinating can decrease the severity of the disease. It is not recommended to vaccinate dogs with suspected CIRDC as it will not decrease the recovery time.

When to Call the Vet

All newly adopted dogs should be examined by a vet within a few days of adoption.

If you notice a hacking, honking cough, discharge from the eyes and nose, decreased activity, or not interested in eating, seek veterinary care for your pet right away.

Read more:

Common Causes of Coughing in Dogs

Kennel Cough

Caring for Pets with Pneumonia

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