Influenza viruses of an assortment of varieties have been the subject of concern for humans, wildlife, and domestic animals for many decades. Dogs were largely felt to be exempt from "the flu" until 2004 when a new canine influenza virus, clearly stemming from the equine influenza virus, was isolated from several groups of Florida racing greyhounds. The problem seemed confined to the racing industry until 2005 when cases involving pet dogs began appearing in boarding facilities.
In the last weeks of September 2005 and continuing into October, numerous warnings to dog owners about a new lethal canine disease swept the Internet. Some of these warnings contained legitimate information while others contained half-truths or information that was simply wrong. Let's sort out the facts from the theories from the misinformation.
Here is an FAQ regarding this relatively new virus that has come to be considered part of the kennel cough complex.
What is Canine Influenza?
On its surface the virus has an assortment of proteins that determine its strain or subtype, and it is against these surface proteins that our bodies mount an immune response. If a viral strain mutates and sufficiently changes its surface proteins, a new strain is created. A new strain is one where the susceptible population has no immunity and infection can spread rapidly.
Unless a mutation occurs as described, influenza virus strains are specific to host species. Human influenza only infects humans. Equine influenza only infects horses. Canine influenza only infects dogs.
Molecular studies indicate that canine influenza represents a mutation from the equine influenza virus. Canine influenza was first confirmed in a racing greyhound in 2004 and has largely been a concern of the racing greyhound industry, particularly in Florida.
Starting in April 2005, the canine influenza virus has been seen in pet populations of many states besides Florida.
What Happens to the Sick Dogs?
Infection rate is high (depending on which report one reads) but 20-50% will simply make antibodies and clear the infection without any signs of illness at all.
The other 50-80% will get symptoms of the "flu:" they will have fevers, listlessness, coughing, and a snotty nose. Most dogs will recover with supportive treatment (antibiotics, perhaps nebulization/humidification, etc.). A small percentage of dogs will get pneumonia. These dogs are at risk for death, and support becomes more aggressive: hospitalization, intravenous fluid therapy, etc. Most of these dogs will recover as long as they receive proper care. Mortality rate is 5-8%
The incubation period is 2 to 5 days and the course of infection lasts 2 to 4 weeks. Because this is an emerging disease, few dogs will have immunity to it.
The point is not to ignore a coughing dog.
How is the Disease Transmitted?
Dogs that are infected will shed virus in body secretions whether or not they appear to be sick. Virus transmission can occur from direct contact with an infected dog or with its secretions. Kennel workers have been known to accidentally bring the virus home to their own pets. The virus persists on toys, bowls, collars, leashes etc.
How are Sick Dogs Treated?
Fevers are treated with anti-pyretic medications or cool water baths. Pneumonia results from secondary bacterial infections (i.e. bacteria invading the lung after the virus has damaged the tissue and compromised its ability to defend itself). Pneumoniain dogs is virtually always secondary in this way, meaning that an initial condition damages the lung and allows bacterial invaders to settle in, and treatment is similar regardless of the cause.
One treatment that might be different in this disease versus other pneumonias or respiratory diseases is oseltamivir (Tamiflu). This is an antiviral medication used in treating human influenza and it is helpful only if used early in the course of infection or in prevention of infection in exposed dogs. For more details on this medication click here.
Can Dogs get Reinfected?
After a dog has recovered from canine influenza, immunity appears to last at least 2 years.
How are Dogs Tested for Canine Influenza?
In a perfect world there would be a simple test that could be performed on a single sample and yield unequivocal results, but there are two main ways to confirm canine influenza infection.
Negative test results are not felt to rule out a diagnosis of canine influenza infection.
Does Vaccination against Kennel Cough (Bordetella) or Parainfluenza offer any Protection against Canine Influenza?
No. These are all completely different infections; however, a vaccine specifically for canine influenza has been released. While this type of vaccine does not completely prevent infection it does minimize the symptoms experienced from infection. Such a vaccine would be helpful for dogs that kennel frequently or for shelters where influenza has been a problem in the past.
Can People Get Infected?
People cannot get infected by this virus. Influenza viruses are specific for their host species and require a dramatic mutation in order to jump species.� One should not be concerned about getting an influenza infection from a dog, horse, or any other species other than a fellow human being.