What is canine infectious respiratory disease complex (CIRDC)?

As I was perusing an ordinary, unbiased, and completely reliable online news source the other day, I noticed an article that included a WARNING for dog owners in south Florida since a “highly contagious virus is spreading across the Sunshine State.” While I’m happy to be given a heads up, I’ve also grown hackles because I suspect another paragon of journalistic integrity is click-baiting a large number of (now terrified) pet owners. The reports around Miami are that a large number of dogs are showing symptoms of canine infectious respiratory disease complex (CIRDC).

Firstly, and let’s get this out of the way: The Centers for Disease Control (CDC) has provided that pets do not play a significant role in the transmission of Covid-19. They CAN get it, but the likelihood of them becoming sick or spreading Covid-19 to humans is most improbable. Yet even so, there are several useful facts to know about CIRDC since most of us enjoy staying calm and informed between headlines.

Featured photo – Ellie doesn’t have the flu, she just has a face full of mud. She’s fine.

CIRDC refers to a syndrome of diseases that can be caused by several different bacterial and viral pathogens. These pathogens are often highly contagious, and synchronic infections are common. Bordetella (kennel cough), distemper, and canine flu fall under the umbrella of CIRDC, as do several other afflictions.

Most dogs are already vaccinated for Bordetella and distemper, yet as fate would have it, spikes in cases of CIRDC happen from time to time.

Public health agencies use the acronym CIRDC during outbreak events because shared symptoms for these contagions consistently occur together.

Clinical signs of CIRDC are typically mild and self-limiting, resolving after about a week. Dogs will exhibit indicators such as coughing, sneezing, and ocular or nasal discharge. Typically, energy and appetite will remain normal.

Dogs that are exhibiting fever, lethargy, decreased appetite, or other more severe manifestations likely have secondary bacterial infections.

Clinical diagnosis of CIRDC is based on a recent history of exposure and physical examination findings. Yet determining the cause requires application of specific diagnostic tests, and results can be difficult to interpret.

Bloodwork, radiographs, and extensive testing may be cost prohibitive for dog owners. The exact cause of a local outbreak may remain unknown in the short-term.

Pathogen-specific diagnostic assays can be performed from specimens obtained with a nasal swab, pharynx swab, tracheal wash, or bronchoalveolar lavage (sample from the lungs).

Samples that are collected after pathogen shedding, or at a location peripheral to the source of infection, could result in a false negative. Sample degradation, recent vaccinations, or infections that aren’t producing symptoms may also lead to false negative results.

Methods of diagnosis are complicated and rely on a significant amount of empirical knowledge. For more information on how public health agencies are able to diagnose canine diseases, see the URL links to the CDC, National Institutes of Health (NIH), and University of Wisconsin-Madison source pages at the bottom of this page.

Antimicrobial treatment is necessary for dogs suspected to have bacterial pneumonia and should be directed by a veterinarian based on bacterial susceptibility results. The development of pneumonia may exacerbate an underlying distemper virus infection or immunosuppressive disease.

Treatment of dogs with uncomplicated signs of CIRDC involves supportive care at home. This can include hydration, nutritional support, oxygen therapy, nebulization (liquid medicine via mist), and coupage (carefully striking the chest to dislodge crud). Further irritation to the trachea may be prevented by avoiding a neck lead and removing barking triggers.

Expectorants or cough suppressants are sometimes recommended by a veterinarian to provide relief. However, a productive cough works to clear bacteria and may serve to reduce the risk of secondary infections.

There are currently no labeled antiviral therapies for dogs with CIRDC.

Large numbers of dogs housed together in animal shelters, boarding facilities, or day-care facilities may create conditions which are conducive to the spread of CIRDC infections. Most agents are transmitted by inhalation of respiratory droplets, although fomite transmission (clothing, bowls, furniture, etc.) can take place with some microbes.

Vaccines are available for common CIRDC pathogens such as canine adenovirus, distemper, parainfluenza virus, canine flu (CIV H3N8 and H3N2), and Bordetella. With the exception of distemper, these vaccines do not produce sterilizing immunity but rather decrease the severity of symptoms and extent of pathogen shedding.

No commercially available vaccines are available for reduction of clinical signs caused by canine coronavirus (CRCoV) and canine herpes.

Special Note – Canine coronavirus is NOT the same virus as SARS-CoV-2 that causes the novel coronavirus (COVID-19). By the way, coronavirus, when viewed from an electron microscope, has a ring of projections that appear like a coronet, or a small crown made of ornaments fixed on a metal ring.

Vaccination is a vital prevention strategy, yet other precautions must be taken because immunization does not protect against all infections. Disinfection, overcrowding prevention, and isolation also work to reduce the risk of CIRDC.

To prevent CIRDC, be sure Bordetella, distemper, and other vaccinations are up to date, and exercise caution before taking your dog to locations where other infected dogs may congregate, especially for extended periods of time.

Supportive care is the most common remedy, while antimicrobial treatment serves to mitigate more serious bacterial coinfections like pneumonia.

Mortality rates for CIRDC are difficult to determine since they depend on many factors including age, vax status, and type of infection. The CDC maintains that less than 10% of CONFIRMED canine flu cases are fatal to dogs.

Extra Credit Section

Bacterial organisms and viruses associated with CIRDC:

Bordetella bronchiseptica – A worldwide cause of respiratory disease in dogs and also causes disease in other species, including cats, pigs, rabbits, and people.

Mycoplasma cynos – The smallest known free-living organisms. Can be isolated from the lungs or trachea of 25% of healthy adult dogs.

Streptococcus equi subsp zooepidemicus – A cause of severe bronchopneumonia in dogs, and a commensal organism of the upper-respiratory tract of horses.

Miscellaneous Bacteria – Streptococcus canis, Pasteurella spp, Pseudomonas spp, Staphylococcus spp, and coliforms, such as Escherichia coli and Klebsiella pneumoniae. These are likely to represent secondary infections.

Canine Adenovirus 2 (CAV-2) – A nonenveloped double-stranded DNA virus that is a worldwide cause of infectious respiratory disease in dogs.

Canine Distemper Virus (CDV) – A virus that causes a myriad of clinical signs, primarily respiratory, with variable gastrointestinal and neurologic signs.

Canine Herpesvirus (CHV) – The major clinical syndrome associated with CHV-1 is reproductive failure in females.

Canine Influenza Virus (CIV H3N8 and H3N2) – Influenza infects a wide variety of animals, including birds and mammals, and significant genetic reassortment can occur.

Canine Parainfluenza Virus (CPIV) – A highly contagious cause of respiratory disease in dogs worldwide.

Canine Respiratory Coronavirus (CRCoV) – This (not covid-19) virus was first described in a group of shelter dogs with respiratory disease in 2003 in the UK.

Other Viruses that have been identified in dogs with respiratory disease include canine reovirus, canine bocavirus, and canine hepacivirus.

National Library of Medicine – CIRDC

Centers for Disease Control – Canine Flu

University of Wisconsin-Madison – CIRDC

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