Recently, you may have seen news stories about canine influenza breaking out in Chicago. What is canine influenza, exactly, and how could it affect your pet? Also known as dog flu, it’s a contagious respiratory disease in dogs caused by a virus known as the canine influenza virus (CIV). Dogs of any age, breed and vaccine status are susceptible. The first strain of CIV was identified by medical experts in September 2005 as “a newly emerging pathogen in the dog population” in the United States.
Infection spreads quickly between dogs through both direct contact and contact with contaminated objects. The virus can stay alive on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours. Almost all dogs that are exposed to the virus become infected. There is no evidence that canine influenza virus can be transmitted to humans or other animal species, with the exception of reports that the strain currently detected in Chicago can be transmitted to cats.
Symptoms, Diagnosis, and Prognosis
Common symptoms of canine influenza include cough, runny nose and fever. Some dogs may experience sneezing, lethargy, and reduced appetite as well. About 80% of infected dogs will have a mild form of the disease. The other 20% of infected dogs do not exhibit symptoms of disease, but can still spread the infection to other dogs as carriers of the virus.
Testing to confirm canine influenza virus infection is available. Your veterinarian can tell you if testing is appropriate. Tests can be performed using respiratory secretions collected at the time of disease onset or using two blood samples; the first collected while the animal is sick and the second 2 to 3 weeks later.
The mortality rate for canine influenza is low (10%). Deaths are usually caused by secondary complications, such as pneumonia, and generally only seen in cases with severe infections.
If your dog is presenting any of the symptoms listed above, schedule an appointment with your veterinarian so that they can evaluate your pet and recommend an appropriate course of treatment.
Treatment largely consists of supportive care to help the dog mount an immune response. There is no specific antiviral medication available, because antiviral medication has only been developed and approved for humans at this time. Therefore, supportive care and appropriate treatment of secondary infections are both important. In the milder form of the disease, this care may include medication to make your dog more comfortable and fluids to ensure that your dog remains well-hydrated. Broad spectrum antibiotics may be prescribed by your veterinarian if a secondary bacterial infection is suspected. Your veterinarian may advise the following to soothe your dog while the condition runs its course:
- Good nutrition and supplements to raise immunity
- A warm, quiet and comfortable spot to rest
- Medications to treat secondary bacterial infections
- Intravenous fluids to maintain hydration
- Work up and treatment for pneumonia
Be advised, while most dogs will fight off the infection within 10 to 30 days, secondary infections require antibiotics and, in the case of pneumonia, hospitalization.
Canine influenza virus can be spread to other dogs via contact with aerosolized respiratory secretions (i.e., particles from coughing or sneezing) from infected dogs. Infection can occur either directly from contact with infected dogs or indirectly through exposure to objects that have been contaminated by infected dogs. Therefore, sick dogs should be isolated from other dogs for about 2 weeks until the infection subsides. Clothing, equipment, surfaces, and hands should be cleaned and disinfected after exposure to dogs showing signs of respiratory disease.
Currently, there are approved vaccines available. Efficacy trials have shown that vaccination significantly reduces the severity and duration of the illness, including diminishing the incidence and severity of damage to the lungs. Additionally, vaccination reduces viral shedding, which means that vaccinated dogs who become infected develop a less severe form of the illness and are less likely to transmit the virus to other dogs.
To date, there is no evidence of transmission of canine influenza virus from dogs to people and there has not been a single reported case of human infection with the canine influenza virus. However, human infections with new influenza viruses (against which the human population has little immunity) would be concerning if they occurred. Influenza viruses are constantly changing and it is possible for a virus to change in such a way that it could begin to infect humans and spread easily between humans. For this reason, the CDC and its partners are monitoring the present strain of the canine influenza virus in Chicago (as well as other animal influenza viruses) very closely. In general, however, canine influenza viruses are considered to pose a low threat to humans.