We all dread "flu season," which will be approaching soon. However, "dog flu" — canine influenza or CIV — is a highly contagious respiratory infection that knows no season and can occur any time of the year.
According to the American Veterinary Medical Association, canine influenza — H3N8 strain — first appeared in January 2004, causing an outbreak in racing greyhounds in Florida. This virus spread quickly to 20 greyhound tracks in 11 states and, by 2007, spread to 30 states and became a nationwide concern.
"A big concern with CIV infection is since this is a novel or mutated virus, all dogs are naive to the virus and will become infected if exposed. This can become a major problem for veterinary hospitals if there is a local epidemic. Since there is an incubation period where they can shed canine influenza virus but not be symptomatic, the disease can easily spread causing bronchitis and pneumonia. The good news is most dogs respond well to symptomatic and supportive care," said Dr. John Kable, of Airpark Animal Hospital in Westminster.
Generally, outbreaks occur in settings where susceptible dogs are in close contact and where there is a high turnover of dogs in and out of facilities such as shelters, dog day care centers, boarding and training facilities, grooming shops, pet supply stores, dog parks, veterinary hospitals and dog shows. The disease is spread by direct contact with infected dogs via airborne particles generated from coughing and sneezing. The virus also contaminates kennel surfaces — walls, floors — food and water bowls, leashes and collars, and the clothing and hands of people who care for infected dogs. According to the AVMA, the virus can remain alive and be able to infect surfaces for up to 48 hours, clothing for 24 hours, and hands for 12 hours. The incubation period is usually two to four days from exposure to onset of symptoms, and dogs are highly contagious during this time when they do not show signs of illness.
The AVMA's resource bulletin states, "Virtually all dogs that are exposed become infected with the virus, but approximately 80 percent develop clinical signs of the disease. The approximately 20 percent of the infected dogs that do not exhibit clinical signs of disease can still shed the virus and can spread the infection."
The symptoms of canine influenza mimics other upper respiratory diseases like kennel cough, but dogs infected with CIV exhibit more serious symptoms that include lack of appetite, lethargy, fever, nasal and/or eye discharge, and a persistent harsh cough. According to Dr. Kevin Fitzgerald, of Animal Planet's "E-Vet Interns," the most severely affected dogs may develop pneumonia, and death can occur in a small percentage — 5 percent — but most dogs recover.
Canine influenza can be diagnosed less than four days into the illness by testing a throat or nasal swab. The most accurate test for CIV is a blood test taken during the first week of the illness, with a second sample collected 10 to 14 days later. More severely affected dogs exhibiting signs of pneumonia — such as a fever of 104 degrees to 106 degrees Fahrenheit — might require chest x-rays.
Like the human influenza, canine influenza needs to "run its course," and treatment involves supportive care: rest, fluids and good nutrition. Dogs usually recover in two to three weeks.
The presence of a secondary respiratory bacterial infection, pneumonia, dehydration, pregnancy, or pre-existing lung disease might require further diagnostic testing and treatment, which might include lung tissue cultures, fluid therapy for dehydration, administering nonsteroidal anti-inflammatory medications to reduce inflammation and fever, and antibiotics.
An effective and safe vaccine for canine influenza was developed and made available in 2009. This vaccine is administered as two shots given two to four weeks apart. The vaccine might not prevent infection, but clinical testing has shown that the vaccination significantly reduces the severity and duration of the illness.
Unfortunately, a new strain of canine influenza — H3N2 — recently surfaced in the Chicago area. According to the Centers for Disease Control and Prevention, the H3N2 strain originated in Asia in 2007 as an avian flu virus that adapted to dogs and has been reported in cats. It is unknown how this strain was introduced into the United States. The current CIV vaccination does not cover the H3N2 strain but might help to reduce the length and severity of the disease.
Here are some suggestions that might help dog owners protect their dogs and deal with canine influenza:
• Consult with your vet to determine if your dog should receive the canine influenza vaccination. Take into consideration your dog's risk for exposure, such as participating in training classes and dog shows, visiting dog parks, pet supply stores or grooming shops, and boarding at a kennel. The canine influenza vaccine is considered as a "lifestyle" vaccine and might not be recommended for every dog.
• Make an appointment with your vet if your dog shows symptoms of canine influenza.
• If your dog has been diagnosed with or shows signs of CIV, do not bring him to facilities where other dogs could be exposed to the virus. Isolate him for two weeks.
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• If other dogs live in your home, practice good hygiene skills when handling the CIV dog. This includes isolating the sick dog for at least two weeks, frequent hand washing, changing clothing that came into contact with the sick dog, and disinfecting all floor surfaces on which the sick dog had contact.