It is rather exhausting to hear so much about influenza. There is a fine line between caution and panic. The media has make this line difficult to identify. My goal here is to prevent as much fact as possible with an occasional injection of opinion.
Influenza is a HOT topic. When words like pandemic and enzootic are used it tends to make people very nervous. The moral of the story: Be cautious, be aware, but DO NOT PANIC.
The Virus:
The images above are all of influenza type A virus. Influenza A virus are further characterized by their H and N subtypes. Swine influenza is H1N1. Horse is H3N8. Seasonal flu is H3N2. The canine influenza that is causing all of the current panic is the H3N8 subtype of virus. This is because there was a jump at some point in history from the horse to the dog.
The current episode of canine influenza is dated to 2004 when there was a rather dramatic epidemic in a racing greyhound population that killed many dogs. Although we have seen influenza steadily since then, serum samples taken from dogs as early as 1999 have been positive for H3N8 virus. Those may have been previous jumps or they may represent the same virus we are seeing now. It's hard to know what used to be around when we weren't looking for it back then. All we can really say is what is here now and keep looking to know what is here in the future.
Transmission/Infection:
The disease is transmitted in exactly the same ways that the human influenza is transmitted. It's stinkin' contagious and is capable of spreading quickly through dense populations. Dogs infected with virus typically have a 2-5 day incubation prior to showing symptoms. They are then "sick" for a period of approximately 5 days. The cough may last weeks longer.
Dogs shed virus several days prior to showing symptoms. This is part of the frustration with the disease because dogs can infect others long before we even know they are sick.
The disease appears to be enzootic (permanently in a population) in Florida, New Jersey, New York, Colorado, and California. It has been diagnosed in 31 states (including Texas) but is still spotty in those states and has not been shown to be permanently in the population.
Transmission is most reliable in situations where a dog is in a larger population of closely housed dogs. This includes: boarding, grooming, dog shows, traveling with the family, dog parks, day care, and racing greyhounds.
Disease Symptoms:
Nearly every dog exposed will become infected. Of those dogs 80% will show some symptoms. Of those dogs 95% show little to no disease and what they do show is limited to:
Cough (deeper, chesty cough)
Mild fever
Lethargy
Nasal Discharge
5% of infected dogs will become more severely ill and those dogs may develop:
Pneumonia
Anorexia
and in rare cases hemorrhagic disease and death.
Greyhounds appear to be exceptionally sensitive to the virus and they nearly always develop more severe disease.
These statistics are smackingly similar to human influenza, yes? I think most dogs are actually at lower risk of exposure than many humans. We humans are such social creatures and are always interacting with random members of our species. We touch door handles, shopping carts, phones, hands, and breathe the same air on public transportation. Aside from the dogs in the at risk population listed above, your dog is probably in a much more controlled environment than you are.
Treatment:
Supportive care. Plenty of water, controlled environment (don't leave a sick dog outside in the cold, wet weather), and watch closely. If the cough is severe enough we will use cough suppressants. If we are dealing with a very young dog, very old dog, or dog with history of cardiopulmonary disease, we may use an antibiotic. Notice how this sounds exactly like how we would treat any old "kennel cough?"
In a few, very sick dogs veterinarians have tried Tamiflu. There are no controlled studies to prove if this works and there are few dogs that are sick enough to warrant treatment. It is NOT recommended for prevention of disease!
Prevention:
Avoid high density situations if there is a local outbreak. Use common sense and if a dog has a cough - DON'T TAKE HIM TO THE PARK OR TO DAYCARE! My daughters have to stay home from school with a fever. Doesn't matter how good they feel. Any fever, vomiting or diarrhea and they have to stay home. It is encouraged that a child with a severe cough not be sent to school. Same concept goes for your dog.
And now the big question: What about the vaccine? Not to sound too redundant, but this is yet another hot topic. Here are a few facts about the vaccine:
- It has only existed on the market for a few months. It looks like it will be a safe vaccine, but it's still new.
- The vaccine is not labeled to prevent disease or eliminate infection - it is designed to reduce severity of clinical signs, shorten disease course, and reduce shedding of virus
- It requires an initial dose followed by a booster 2-4 weeks later. It must then be boostered annually.
As with any vaccination of its type, protection will not happen until around 10 days AFTER the SECOND vaccine. So you must plan ahead if you want your dog "protected" prior to entering a boarding facility. You need a MINIMUM of 24 day lead-time and closer to 5 weeks is recommended.
Which dogs should get the vaccine? High risk dogs (see the above list) and especially high risk dogs traveling to or living in the areas of NJ, NY, CA, CO, or southern Florida.
Your veterinarian may have identified a local outbreak of influenza and may feel that vaccination for your pet is important regardless of where you live. Always follow your primary care veterinarians recommendations regarding what vaccinations are recommended for your pet.
I don't have statistics regarding the H3N8 in other countries. I would imagine it is in Canada and Central America, but nobody has mentioned this on my discussion boards. I'll keep looking.
AMH
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