Last week we talked about H1N1 (Swine Flu) that has affected people, pigs, ferrets, and cats. This week the topic is the dog flu. H3N8, canine influenza, was discovered in 2004 in racing Greyhounds in Florida and is highly contagious from dog to dog, but has not been shown to go from dog to human.
Canine influenza is spread just like the human flu, by the air through coughing, contaminated objects (kennel surfaces, food and water bowls, collars and leashes), and people moving between sick and healthy dogs. The virus can remain viable (alive and able to infect) on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours! The time from infection to clinical signs is usually two to four days, the incubation period. Dogs are most contagious during this 2-4 day incubation period when they are not showing signs of illness. Because this virus is so new, all dogs, regardless of breed or age, are susceptible to infection and have no naturally acquired or vaccine-induced immunity when first exposed to the virus. If the virus enters a kennel or other closed group, a high percentage of the dogs may become infected, and most of these dogs will come down with clinical signs.
Like other influenza viruses, CIV causes an acute respiratory infection in dogs. However, unlike human influenza, CIV is not a “seasonal” flu – infections can occur year-round. Canine influenza virus causes a clinical disease that mimics kennel cough. As a result, infection with the virus is frequently mistaken for infections caused by Bordetella bronchiseptica (the bacteria that causes kennel cough). Clinical disease of CIV may be mild or severe. The majority of infected dogs exhibit the mild form of canine influenza- coughing for 10-21 days despite treatment with antibiotics and cough suppressants. Many dogs have a nasal discharge and a low-grade fever. The nasal discharge is usually caused by secondary bacterial infections. Some dogs are more severely affected with clinical signs of pneumonia, such as a high-grade fever (104°F to 106°F) and increased respiratory rate and effort.
The easiest way to test for the CIV, is to test the serum (a blood sample). Paired serum samples (taken within the first 7 days of illness) and convalescent serum samples (taken 10-14 days later) are necessary for diagnosis of recent infection.
As for all viral diseases, treatment is largely supportive. Good husbandry and nutrition may assist dogs in mounting an effective immune response. A secondary bacterial infection usually resolves quickly after treatment with antibiotics. Pneumonia in more severely affected dogs responds best to a combination of antibiotics (to combat secondary bacterial infections) and maintenance of hydration via IV fluids. Most dogs recover from canine influenza within 2-3 weeks.
In May 2009, the USDA approved the licensure of the first influenza vaccine for dogs developed by Intervet/Schering Plough Animal Health Corporation. The vaccine is intended as an aid in the control of disease associated with CIV infection. Although the vaccine may not prevent infection altogether, trials have shown that the vaccination may significantly reduce the severity and duration of clinical illness, including the incidence and severity of damage to the lungs. Vaccinated dogs that become infected develop less severe illness and are less likely to spread the virus to other dogs. These benefits are similar to those provided by influenza vaccines used in other species, including humans. The canine influenza vaccine is a “lifestyle” vaccine, and is not recommended for every dog. In general, the vaccine is intended for the protection of dogs at risk for exposure to the CI virus, which include those that either participate in activities with many other dogs or are housed in communal facilities, particularly where the virus is prevalent.
If you are at all concerned that your furry baby may have canine influenza, please see your veterinarian ASAP.
Samantha Yeltatzie, DVM
I-10 Pet Emergency
10822 Fredericksburg Road
San Antonio, TX 78240