Canine Influenza Virus: Diagnosis, Treatment and Control
Canine influenza is still a relatively new virus and vaccination is not widespread, so most dogs will be susceptible to infection. After diagnosing it, here are the steps you'll want to take for treatment and control.
Clinical suspicion of CIV cannot be used as a substitute for appropriate laboratory testing. Numerous viral and bacterial pathogens can produce very similar clinical signs, and thus diagnostic testing must be performed to determine the specific underlying cause(s).
Dr. Stephanie Janeczko, Senior Director of the ASPCA’s Shelter Medical Programs, notes that when dealing with infectious respiratory disease in dogs, it's also important to remember that the same pathogen can have a mild presentation in one animal, yet cause severe or even fatal disease in another.
Canine influenza virus can be diagnosed by PCR performed on deep nasal and/or pharyngeal swabs; samples should be collected within one to two days of the onset of clinical signs. Because viral shedding peaks early in the course of disease, this test is of little value in dogs who have been ill for several days. Instead, blood samples from these dogs can be tested for antibodies against CIV.
Treatment of CIV
After prompt identification, treatment is usually symptomatic and supportive in nature. It’s aimed at preventing secondary bacterial infections as well as providing definitive treatment, if appropriate, for any primary pathogens and other medical conditions. More severely affected dogs require more aggressive treatment, which may include hospitalization, intravenous fluid therapy, oxygen support, nebulization and coupage.
Although CIV is not particularly resilient in the environment, adequate cleaning and disinfection practices are necessary to limit transmission. Most disinfectants routinely used in animal shelters—including quaternary ammonium containing compounds, sodium hypochlorite, accelerated hydrogen peroxide and potassium peroxymonosulfate—are effective against CIV when used appropriately.
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.
Vaccination against canine influenza virus may be a helpful tool in limiting disease in the shelter setting. There are currently two pharmaceutical manufacturers that offer CIV vaccines for the H3N8 and H3N2 strains. Vaccination will not completely prevent infection, but it can reduce the severity and duration of disease. All currently available vaccines are inactivated (killed) virus products and require two doses given 2-4 weeks apart. Because an optimal immune response should not be expected until approximately one week following the second dose (i.e. three weeks following the initial vaccination), CIV vaccination provides limited benefit, particularly in the sheltering setting, unless exposure can be prevented during this time. The decision to vaccinate privately owned animals should be discussed with personal veterinarians based on the pet’s lifestyle.
Dogs should also receive core vaccinations in accordance with current shelter guidelines. Dr. Janeczko says these vaccinations provide protection against other pathogens in the canine infectious respiratory disease complex and can reduce the morbidity associated with co-infections.
Reducing Stress, Crowding & Length of Stay
Perhaps the most critical of all control measures are reduction of stress and crowding. Crowding is an extremely potent stressor of dogs and exacerbates many negative factors with which shelters already struggle. High-density housing, particularly when young and immunologically naïve dogs are intermixed with other dogs in the facility, is a significant risk factor for disease.
In one large urban shelter, the odds of a positive serologic test result increased significantly by 2.2 for every three additional days in the shelter. 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 and reduces the risk of direct or indirect contact with infected animals. It is critical that organizations operate within their capacity for care to ensure that they are able to provide a humane level of care to the animals in their facility.
Direct physical benefits of stress reduction include lowering circulating cortisol levels, which have a negative effect on animals’ immune systems and their ability to fight off infection. Reducing stress will also decrease barking, which can help to reduce respiratory irritation and aerosol spread of pathogens.