Canine Influenza

H3n8
Influenza viruses have plagued man for a very, very long time. They’re highly adaptable, showing the ability to jump from species to species. They change frequently, making it hard to develop protective methods to stop infections from spreading. They’ve been responsible for some of the deadliest disease outbreaks on the planet.

In 1918, a particularly nasty flu virus swept the globe. This vicious strain was thought to have come from a mixing of avian and human flu in pigs. In 2 years, between 50-100 million people died (3% of the world’s population). This flu pandemic killed more people in a year than the Black Plague killed in 100 years. The most deaths occurred in young, healthy people, which are normally the most resistant to disease. It’s believed that these people had such a violent immune reaction to the virus that their own body was damaged to the point of death.
CampFunstonKS InfluenzaHospital

Needless to say, we need to take Influenza viruses very seriously.

In 2004, a large number of racing Greyhounds at a track in Florida got sick with respiratory signs. The disease resembled kennel cough, but some of the dogs were far sicker than is usually seen with ‘regular’ kennel cough. Extensive testing eventually revealed that an equine influenza virus had changed just enough to allow it to infect dogs. Currently, this virus has not infected any people.

Canine influenza has the official “name” of H3N8. These letter-number combinations describe the viruses based on their structure. The “H” stands for hemagglutinin protein; “N” for neuraminidase protein.
Perro tosiendo

Signs and symptoms in dogs include cough, runny nose, fever, and in some patients, severe respiratory distress. While most dogs don’t get severely sick, about 8% do develop severe or life-threatening illness.

Spread and infection in dogs happens by aerosol transmission. Dogs that cough and sneeze send little droplets of moisture into the air that contain the virus. Normal breathing can also spread the virus in the air. People and inanimate objects that are contaminated by respiratory fluids from a dog can pass the infection on to other dogs. Once a dog is infected, it will actually be able to spread the virus for a few days before it shows any signs of being sick. Places that have lots of dogs in an enclosed area are massive risks for transmission of Canine Influenza: boarding facilities, daycare, groomers, veterinary hospitals, kennels. This is a completely new virus for dogs, so 80% of those exposed to the virus will get sick.

Testing and treatment are both available. Samples of respiratory secretions or blood testing can be done to determine if a dog with respiratory illness is suffering from the H3N8 virus. Treatment is generally just supportive care. IV fluids, antibiotics to prevent a bacterial pneumonia from happening, and time. The severely affected dogs may need oxygen therapy or intensive care. Most patients will survive H3N8 infection.

A vaccine is available for Canine Influenza. Dogs have to be vaccinated twice, about 3-4 weeks apart, to be protected. The vaccine has to be boostered once a year. While the vaccine does greatly reduce the chances of a dog becoming gravely sick from H3N8, it does NOT completely stop the infection from occurring. It’s the only vaccine on the market at this time.
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Do dogs in Michigan need to be protected? That’s a good question. Better than half of the states in the US have had canine influenza outbreaks, but Michigan is not currently one of them. Ohio and Illinois have had outbreaks. Somehow, we’ve dodged the bullet so far.

There are two choices: vaccinate BEFORE the outbreak, or vaccinate after. I certainly can identify with not vaccinating dogs for something that’s not even present in the state yet. However…The first choice is preferable because of the ease with which H3N8 is transmitted. Once it gets into the population here in Michigan, it is going to rapidly spread. Because it takes 6 weeks for the vaccine to reach peak effect, it may be difficult to protect dogs in an area where the virus has already shown up. A giant rush to get vaccinated will also cause high numbers of dogs to visit the hospital, which is just asking for trouble because of the way influenza is transmitted.

I prefer to give as few vaccines as possible, so we are recommending the influenza vaccine for any patients that are ‘social’ dogs at this time. If your dog goes to the groomer, boards anywhere, goes to daycare, goes to a dog park, travels to other states, goes to dog shows, or is social with other dogs in the family or neighborhood, you should strongly consider the vaccination. (These recommendations are the same for the Bordetella vaccine.) The vaccine is safe and we’ve been using it since 2009 when it was approved for use in dogs.

You can read more about the H3N8 virus and vaccination at the vaccine manufacturer’s website.

More information about Canine Influenza can be found here.

The AVMA’s page about Canine Influenza is a very detailed look at the virus.

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1 Comment

Filed under immunology, infectious diseases, preventive care, vaccines

One response to “Canine Influenza

  1. Chris

    Prevention is always better than damage control.

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