Canine Influenza - Background for Professionals

Background for Professionals | Talking Points for Staff | Client Fact Sheet

An increasing number of pet dogs have been diagnosed with canine influenza, a newly emerging respiratory pathogen, over the last few months. Previously found in racing greyhounds, the virus mutated from an equine strain of influenza and is highly contagious. The virus causes an acute respiratory infection that is characterized by signs that mimic “kennel cough” but is more serious and generally requires veterinary medical attention.

Canine influenza cases have been reported in dogs from throughout the U.S. and Canada. Cases have been confirmed in Florida, New York, and possibly Massachusetts, according to veterinary researchers working in collaboration with the Centers for Disease Control. Confirmed cases have involved dogs from shelters, humane societies, boarding facilities and veterinary clinics.

Because canine influenza is a newly-emerging disease, all dogs, regardless of breed or age, are susceptible to infection and have no naturally-acquired or vaccine-induced immunity. Nearly 100 percent of exposed dogs will become infected and about 80 percent will exhibit clinical signs.

Clinical Signs

There are two general clinical syndromes – a mild syndrome and a more severe pneumonia syndrome. Most dogs will experience the mild syndrome, with signs similar to “kennel cough,” such as a cough that persists for 10 to 21 days despite therapy with antibiotics and cough suppressants. Dogs may also have nasal discharge and a low-grade fever.

Dogs that develop a more severe pneumonia syndrome may have a high-grade fever and increased respiratory rate and effort.

Fatality Rate

The mortality rate is believed to be low, between one and eight percent. The mortality rate can be higher in immuno-suppressed dogs and very young and old dogs.

Incubation/Shedding Period

Clinical signs may appear two to five days after exposure and infected dogs may shed the virus for seven to 10 days after the first day they exhibit clinical signs. About 20 percent of infected dogs will not show clinical signs but are still able to spread the infection.

Transmission

The virus is spread by aerosolized respiratory secretions, contaminated inanimate objects and by people moving back and forth between infected and uninfected dogs.

There are no known cases of the canine flu infecting humans.  

Diagnosis

Nasal swabs and serology tests may diagnose the flu. Diagnostic tests will detect antibodies to the canine influenza virus, which may be identified as early as seven days after the onset of clinical signs.

While there is no quick diagnostic test available for dogs with an influenza virus infection, researchers are working to develop an in-house diagnostic test for veterinarians. Veterinarians can send blood samples to the Animal Health Diagnostic Center at the Cornell School of Veterinary Medicine for diagnosis.

Treatment

Researchers are working to develop a canine influenza vaccine; however, there is not one available at this time. Cynda Crawford, DVM, PhD., who studies canine influenza at the University of Florida, recommends that veterinarians prescribe a combination of wide-spectrum antibiotics if a secondary, bacterial infection occurs.

In the more severe syndrome, dogs with pneumonia may develop a secondary bacterial infection that may respond to a combination of broad-spectrum antibiotics and intravenous fluid therapy.

Prevention

Currently, there is no vaccine for canine influenza. Although the signs of canine influenza mimic those of “kennel cough,” there is no protection afforded by the Bordetella vaccine against the influenza virus. The virus is most likely killed by routine disinfectants, such as ammoniums and 10 percent bleach, so good housekeeping practices may reduce the likelihood and rate of transmission.

Because the virus is highly contagious and all dogs are susceptible to infection, veterinarians are advised to use contagious disease protocols for all dogs that exhibit signs of respiratory infection. Dogs exhibiting signs of respiratory disease should be brought into the practice through an area where they will not pass other animals, such as a back door rather than the main entrance. Veterinarians are encouraged to use similar safety protocols as they would use in cases of parvovirus.

For More Information

Contact your state veterinarian for local incidence information. The following links provide more information from a variety of sources. 

CDC Media Briefing on Canine Influenza

Veterinary Advisory from University of Florida College of Veterinary Medicine on Canine Influenza Virus

JAVMA: Canine Influenza Virus Emerges in Florida

NEWStat article

Healthypet Article: Fast Facts About Canine Influenza

Posted October 3, 2005