Know the Facts: Canine Infectious Cough
By Michelle Evason, BSc DVM DACVIM
& Jason Stull, VMD, MPVM, PhD, DACVPM
Canine Infectious Respiratory Disease Complex (CIRDC) is known by many names, the most common being ‘kennel cough’. It has recently been defined as a syndrome (spectrum of clinical signs) in dogs, and is associated with a number of bacteria and viruses.
Acute onset of a harsh cough is the hallmark of CIRDC, and dogs may have concurrent sneezing, ocular (eye) or nasal discharge (or both). Typically, dogs improve within 7–10 days with basic nursing care, and the disease does not generally require extensive diagnostic testing or specific drug therapy.
Who gets it and why?
This is a very common clinical syndrome in dogs, and frequently related to infection with one or more combinations of the following bacteria and viruses:
Bacterial causes: Bordetella bronchiseptica, Streptococcus equi subspecies zooepidemicus and Mycoplasma spp. Other animal species, including cats, can be infected with these bacteria.
Viral causes: Canine adenovirus 2, canine distemper virus, canine respiratory coronavirus, canine influenza viruses, canine herpesvirus and canine parainfluenza virus.
Can people get sick with it?
Human infection from dogs is unlikely; infections with Bordetella bronchiseptica have rarely been reported in people (generally those who are highly immunocompromised).
How is it spread (transmitted)?
Most commonly, infection is spread directly from the respiratory tract (nose, throat) of one infected dog to another. Gastro–intestinal shedding (from feces) may occur with distemper virus. Transmission may also occur through contaminated fomites, such as bedding, grooming equipment or human hands. High-density canine housing (e.g. boarding facilities, shelters, doggie daycare, kennels) or events with large dog groups (e.g. dog shows, puppy classes) with frequent dog mingling and interactions increase risk of both exposure and transmission. Veterinary hospitals are another source of infection between dogs.
Time to infection is short for most bacterial and viral pathogens (2-10 days), and co–infection (multiple bacteria and viruses involved in one dog) is common. Many CIRDC pathogens can be present without clinical disease, which presents a challenge for diagnosis and prevention, i.e. bacteria or viruses can be present incidentally and without obvious disease signs.
The majority of the pathogens involved in CIRDC are short–lived in the environment. Different pathogens vary in importance based on geographic location and sometimes season.
What should I look for?
(Signs of disease)
In dogs, the ‘goose honk’, harsh or honking cough is classically reported or elicited on palpation (pressure) of the trachea in an otherwise bright and alert pet. Pet owners often report gagging, retching or vomiting. Nasal or ocular discharge is frequently present, along with mild fever. Dogs infected with distemper virus may have skin, ocular or intestinal disease (diarrhea) along with respiratory signs.
Less commonly, more severe difficulty or changes with breathing due to pneumonia can occur.
How is it diagnosed?
Canine Infectious Respiratory Disease Complex is diagnosed based on history of likely exposure to infected dogs (e.g. recent shelter adoption, etc.) and physical exam. Extensive diagnostic testing is not typically advised or necessary (aside from severe or long–lasting progressive disease or in outbreak scenarios with multiple dogs affected) due to similarities between pathogens and high likelihood of co-infections.
What is the treatment?
Therapy for CIRDC entails supportive nursing care, rest and ‘tincture of time’, as infection is self-limiting in less than 7–10 days in most dogs. Cough suppressant therapy may be considered, together with reducing tracheal stimulation, e.g. use haltie or harness instead of pressure from a collar.
Progressive disease or fever, mucopurulent (pus) nasal or ocular discharge, not eating and/or lethargy may prompt consideration of antimicrobial therapy. Patients with pneumonia should be treated with appropriate antimicrobials.
Will the pet recover (prognosis)?
Most dogs have an excellent prognosis, complete disease resolution and cure. Dogs with distemper virus infections have a guarded prognosis.
How can it be prevented?
Vaccination is considered core for many CIRDC associated viruses. Vaccination also decreases severity and risk of infection for Bordetella bronchispetica.
Vaccination is not completely protective, and it is important to convey to pet owners that, while vaccination will reduce risk and severity of infection due to many CIRDC pathogens, it cannot prevent all disease risk.
Transmission of many of these pathogens can be effectively reduced with decreased canine mingling and stress, together with rapid identification of ill dogs and proper infection control.
Resources
1. ISCAID Respiratory Guidelines: http://www.wormsandgermsblog.com/files/2017/02/Lappin_et_al-2017-Journal_of_Veterinary_Internal_Medicine.pdf
2. WSAVA 2015 Vaccine Guidelines: http://www.wsava.org/guidelines/vaccination-guidelines
3. Disease Prevention at Canine Group Settings: http://vet.osu.edu/preventive-medicine/vpm-research/disease-prevention-canine-group-settings