Canine Infectious Respiratory Disease Complex (CIRDC), sometimes called dog flu, canine flu or kennel cough, remains a particular concern for shelters (as well as other facilities where large numbers of dogs are housed in close proximity to one another, such as boarding facilities) because of significant infection rates and ease of transmission.
Prompt identification and diagnosis of cases, treatment of infected dogs, and implementation of control measures is critical.
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Timely removal of clinically affected dogs to strict isolation must be undertaken to limit the spread of disease. Dogs should be moved as soon as possible once clinical signs are noted, as the intensity of shedding does not necessarily correlate with the severity or duration of clinical signs observed.
Although isolation of obviously affected individuals is a cornerstone of effective disease control, it is important to realize this may not be sufficient to limit all transmission of CIRDC.
Depending on the pathogens involved, some dogs will become infected but never show outward clinical signs, some will become contagious before signs develop and some will remain contagious even after they have recovered.
For this reason, complete separation of exposed dogs from unexposed and newly arrived dogs may be necessary.
Most of the pathogens are efficiently transmitted by direct oronasal contact as well as aerosolization of respiratory secretions from infected dogs. Thus, wherever possible, isolation areas should have separate ventilation to reduce the risk of further airborne transmission of CIRDC.
Appropriate precautions to prevent further spread of disease and to protect shelter, household, and/or community pets and people must be implemented. Special care should be taken to protect the health of other dogs in the facility as well as that of other species, including humans, given the potential for transmission.
There has been at least one report of clinical disease in cats in a cattery setting caused by Streptococcus equi as well as transmission from an infected dog to his handler, and Bordetella bronchiseptica is also known to infect both cats and, rarely, humans.
Contact with infected dogs should be restricted to key staff and volunteers. Whenever possible, these individuals should not work with other dogs. If this is not feasible, appropriate personal protective equipment (PPE) must be worn and dogs should be handled in isolation only after handling healthy animals in the general population.
Depending on the nature of the disease and available resources for treatment, placement into foster care, release to rescue organizations, or hospitalization at a private veterinary clinic may be appropriate options for infected dogs.
Sanitation protocols, procedures for movement of animals through the facility, and preventive medicine protocols must be reviewed periodically and whenever an outbreak is identified.
Although most of the various CIRDC pathogens are not particularly resilient in the environment, adequate cleaning and disinfection practices are necessary to limit transmission. Canine adenovirus is a notable exception and thus disinfectants with efficacy against non-enveloped viruses (e.g. sodium hypochlorite or similar products, potassium peroxymonosulfate, accelerated hydrogen peroxide) must be used.
A thorough review of sanitation procedures should include an evaluation of the product(s) used as well the manner in which they are diluted and applied to various surfaces by staff (including allowed contact time); this evaluation should consider written protocols as well as a visual assessment of these procedures as they are actually performed.
In addition, staff assignments should be made to limit the spread of disease and reduce fomite transmission, including restricting access to small subsets of the population, the use of appropriate personal protective equipment and the provision of dedicated supplies used only in limited areas of the facility.
CIRDC is not a vaccine-preventable disease, but proper vaccination protocols are important in minimizing the frequency and severity of infectious respiratory disease in shelter dogs. While vaccines are commercially available for many of the more common and serious pathogens associated with the disease complex, others (including canine respiratory coronavirus, herpesvirus, and pneumovirus as well as Mycoplasma spp. and Streptococcus equi subsp. zooepidemicus) do not exist or are not currently available for use in the United States.
In addition, many of the products that are available simply limit severity without preventing infection, creating a situation where respiratory disease can still be frequently seen despite adherence to recommended vaccination protocols appropriate for dogs in animal shelter settings.
It is critical that animals entering the facility receive appropriate vaccinations at or before their entry to the shelter in order to maximize effectiveness and reduce the risk of disease outbreaks. Staff training should be periodically provided to ensure that vaccinations are being handled appropriately (e.g. kept refrigerated, reconstituted prior to use) and administered in compliance with shelter protocols.
Core vaccinations for shelter dogs include a modified live injectable product containing canine distemper virus, canine parvovirus, and canine adenovirus-2 given parenterally as well as intranasal vaccination using a bivalent product that contains Bordetella bronchiseptica and canine parainfluenza virus.
Vaccination against canine influenza may be appropriate in some facilities, but immunity should not be expected until approximately one week following the second dose (e.g. three weeks following initial vaccination).
Stress and Crowding Reduction
Perhaps the most critical of all control measures is the reduction of stress and overcrowding, so it’s important that shelters understand and operate within their capacity for care.
Overcrowding is an extremely potent stressor of dogs and exacerbates many negative factors that shelters are already struggling with. High-density housing, particularly when young and naïve dogs are intermixed with other dogs in the facility, is a significant risk factor for disease.
Length of stay in a shelter environment has been shown to be a risk factor for seroconversion and development of clinical signs associated with CIRDC pathogens. Keeping fewer dogs in the facility at any given time, particularly by reducing the length of time they spend in the shelter, generally improves the level of animal care and sanitation that can be provided and reduces the risk of direct or indirect contact with infected animals.
Direct physical benefits of stress reduction include reductions in circulating cortisol levels and decreased barking, which in and of itself can help to reduce respiratory irritation and aerosol spread of the causative agents.
In-shelter treatment is usually symptomatic and supportive in nature and aimed at preventing secondary bacterial infections.
Antibiotic therapy is indicated for primary and secondary bacterial infections, which do occur commonly in shelter settings. Although it is ideal to make therapeutic choices based on sensitivity results, this is seldom possible on a consistent basis for all infected dogs due to financial and logistical restraints.
Initial therapy can be prescribed based on likely pathogens and basic information about the antibiotic selected, but no one choice will be appropriate for all cases. For example, doxycycline often has good efficacy against Bordetella and Mycoplasma but would be expected to be less successful when used to treat dogs infected with Streptococcus equi subsp. zooepidemicus.
The use of steroids, cough suppressants, and expectorants is generally not recommended in the shelter environment. Because coughing is often exacerbated with excitement, exercise (particularly pulling on the leash) and barking, appropriate environmental modifications should be made to limit these triggers.
More severely affected dogs require more aggressive treatment, which may include hospitalization, intravenous fluid therapy, oxygen support, nebulization and coupage. If it is not possible to provide such intensive treatment or if inadequate response to treatment is noted in individual cases these dogs must be considered for transfer to a private veterinary facility or for humane euthanasia.
Humane conditions and medical care, as well as adequate isolation space to prevent transmission to the rest of the population, must be available. Depending on the size of the facility, number of staff and number of infected dogs it may become necessary to temporarily halt intake to avoid jeopardizing the health of incoming animals and avoid the need for depopulation. The need for such drastic action is rare and should be utilized only as a carefully considered last resort.