Canine influenza

Recently (in September 2005 in Vancouver) the various news media have carried reports of a "new" deadly virus of dogs.

The disease they are talking about is influenza, or "dog flu". This is a fairly recent phenomenon in dogs, having first been reported about 10 years ago. The strain of virus infecting dogs is actually an equine (horse) influenza virus that has "jumped species" and become infectious to dogs. This is the same thing that the swine flu did back in the 80s (jumping from pigs to people) and avian influenza has done recently world-wide (jumping from birds to people).

The first reported cases were in greyhounds at racetracks down in Florida. The original outbreak many years ago appeared to die out on its own. In the last year, however, it made a resurgence in the track greyhounds. It has also been seen in some shelters and breeding kennels, and other breeds (outside the greyhound population) have been involved.

This disease is of particular concern because all dogs, regardless of age or vaccination status, are susceptible. Because this virus is new in the species, the dog population is "naive". They have had no natural exposure through which to gain immunity, and there is no vaccine at this time.

Infection rates

Nearly all dogs that are exposed develop infection. Of the dogs that become infected, about 80% develop clinical signs (i.e. become sick with the disease). The other 20% are able to mount an immune response adequate to ward off the disease, and never show signs of illness.

There is a 2 to 5 day incubation period between exposure and the development of clinical signs. Dogs will be infectious and shed the virus for 7 to 10 days after they start to show signs. The 20% of dogs who don't develop any clinical signs can be "silent" shedders, passing the virus on to other dogs though they show no signs of illness themselves.

Clinical signs

There are two general courses of the disease. Most dogs develop a mild form.  Symptoms are similar to those of "kennel cough complex". That is, dogs present with varying degrees of coughing, from a moist cough to a dry hack. Sometimes there is a low-grade fever, and occasionally nasal discharge due to a secondary bacterial infection. These secondary infections usually respond well to broad-spectrum antibiotics.

A small percentage of infected dogs develop more severe disease, with persistent cough, higher fever, and pneumonia. These dogs require hospitalization, intravenous fluids, intravenous antibiotics, and antiviral medication.

The fatality rate with this disease is low, contrary to the media reports. The estimates range from 1 to 5% of symptomatic dogs, with most experts estimating in the 2-3% range.

So how do we know whether it's "kennel cough complex" or influenza?

That's a tough question. At present, there is no fast way to determine this. The veterinarian who did the original epidemiology on the outbreak in the Florida greyhounds does serum testing for antibodies to equine influenza. These antibodies will be present 7 days after infection, and the antibody levels will rise over the next 2 weeks. A definitive diagnosis of influenza is made using paired "acute and convalescent serum" samples. A sample is taken when the dog is sick (acute sample), and another 2 weeks later (convalescent sample). A rising antibody level from one sample to the next is diagnostic for canine influenza.

Confirmation is not germane to treatment. Results are not available until the patient is recovering. Treatment is based on the clinical signs and how the dog responds to medication, among other things.  The test is very important, however, in allowing us to determine whether this disease is present in our area and what proportion of the dog population might be affected.

Canine influenza in Vancouver

Thus far we have NO confirmed cases in BC. There is no evidence that this disease is in our canine population.

Preventing canine influenza

The disease is spread like the human flu, by airborne particle expelled when an infected dog coughs. It can also be spread by "fomites", or inanimate objects like toys, balls, rawhide bones, grooming tools, and other items that might be contaminated with respiratory secretions. It can be carried from dog to dog on clothing and hands.

Most routine disinfectants should kill the equine/canine influenza virus.

Dogs exposed to higher risk situations like kennels, daycare, dog parks, shelters and pet stores should be monitored carefully for respiratory signs. Dogs showing any signs of respiratory disease should be quarantined.

There is no good way to prevent your dog from coming in contact with this disease should an outbreak occur, short of keeping him in relative quarantine. Certainly keeping your dog away from others that are coughing is a reasonable precaution at any time, but is an absolute must if this disease is detected locally.

Check this web page for updates - we will post further precautions you should take if and when canine influenza is ever found in our area.

Reality check

Canine influenza at this time is to dogs as SARS was to humans in 2003. We heard about it a lot in the media despite the low risk to people outside the affected hospitals in Toronto.  That seems to be the case with canine influenza in the last couple of years. The story seems to crop up sporadically on slow news days, or when a media outlet feels like it is being "scooped" by another.

This disease is rare even in Florida and the surrounding states, and it is not yet established in a dog population near us. The likelihood that we will see this virus here is small, and if we do, we will deal with it at that time.  Being informed is a good thing; panicking needlessly is not! This web page will be updated with information relevant to our dog patients, as it becomes available.