By Dr. Bruce W. Little
A little more than a year ago, it was reported that at least 41 states had experienced outbreaks of canine influenza. Today, it’s safe to assume that canine influenza has spread to all 50 states across the USA. Canine influenza is caused by infection from an influenza Type A virus, the canine influenza virus (CIV). Currently two different canine influenza viruses have been identified. They’re named using the letters H and N designation, just like like the human flu virus.
Canine influenza was first identified as H3N8 in Florida in 2004. It’s believed to have originated in horses, and then developed the ability to infect dogs through mutation. That virus spread across the US, but didn’t initially reach epidemic proportions except in Greyhound racing kennels and some animal shelters.
However, in March 2015, there was a serious outbreak of canine influenza in the greater Chicago area that infected thousands of dogs, killing many. It was thought at first this was the H3N8 virus, but laboratory tests identified it as H3N2 virus, which had been found only in Southeast Asia. It had apparently mutated from avian influenza to dogs. Influenza viruses are highly contagious and can spread rapidly among susceptible pets. Prior to the 2015 outbreak, all dogs were highly susceptible because the virus had not been identified in the United States. Also, in March 2016, we realized the inter-species transmission potential, as an isolated canine H3N2 virus outbreak occurred in cats at an Indiana animal shelter.
What are the Symptoms of Canine Influenza?
Influenza is part of the canine infectious respiratory disease complex. This complex includes Bordetella, or “kennel cough,” and other infectious agents. There are several other illnesses that cause the same symptoms as canine influenza, so it’s best to call your veterinarian about the signs you’re seeing in your dog.
- Mild form — Dogs suffering with a mild form of canine influenza develop a soft, moist cough that persists for 10 to 30 days. They may also be lethargic and have reduced appetite and a fever. Sneezing and discharge from the eyes and/or nose may also be observed. Some dogs have a dry cough similar to the traditional “kennel cough.” They may also have a thick nasal discharge, which is usually caused by a secondary bacterial infection.
- Severe form — Dogs with a severe form of canine influenza develop high fevers (104ºF to 106ºF) and have clinical signs of pneumonia, such as increased and difficult respiratory rates, worsening cough, and collapse. Pneumonia may be due to secondary bacterial infection.
Why Has There Been a Sudden Outbreak of Canine Influenza?
There’s no logical explanation of why or how the Southeast Asia virus spread to the United States. Perhaps it was transmitted with a visiting dog or pet owners from Asia. The canine influenza viruses can spread quickly when there are many dogs together in one area, such as boarding and grooming facilities, dog parks, nature trails, dog day care centers, humane societies, animal shelters, and even animal hospitals.
As with the influenza virus that infects people, the canine viruses are airborne and easily spread through contaminated toys, beds, dishes, human clothing or contact with an infected dog. Because this is still an emerging disease and dogs in the U.S. have never been exposed to it, almost all dogs, regardless of breed or age, lack immunity to it and are susceptible to infection if exposed.
Virtually all dogs exposed to the virus become infected, and nearly 80 percent show clinical signs of disease, though most exhibit the mild form described above. However, the risk of any dog being exposed to the canine influenza virus depends on that dog’s lifestyle. Dogs that are frequently or regularly exposed to other dogs are at greater risk of coming into contact with the virus. Also, as with other infectious diseases, extra precautions may be needed with puppies, elderly or pregnant dogs, and dogs that have compromised immune systems. Dog owners should talk with their own veterinarian to assess their dog’s risk.
How Do Doctors Diagnose and Treat Pets for Canine Influenza?
There is no rapid test for canine influenza in dogs. It may take days or weeks to get test results, so most doctors will determine if the dog needs treatment before they have a definitive diagnosis. Tests may be performed through blood work, respiratory tract samples, chest X-rays and general physical examinations. Treatment may include antibiotics if there is a secondary bacterial infection, cough suppressants and intravenous fluids if dehydration is observed.
Have your veterinarian observe your dog and differentiate between respiratory conditions. Your doctor is best qualified to make a diagnosis of canine influenza.
Is There a Vaccine for Canine Influenza?
Preventing your dog from contracting canine influenza is the best scenario possible. Talk to your veterinarian about the risk factors that may affect your dog. Find out if there are widespread cases of canine influenza in your area, or in places that you may be visiting. Make sure boarding kennels, dog day care facilities, groomers and dog-sitters are aware of the potential for your dog regarding canine influenza, and that they take all precautions necessary to keep the disease contained.
Ask your veterinarian if your dog should be vaccinated against canine influenza, as there has been a government approved vaccine against H3N8 influenza since 2009, and recent approvals for vaccines to immunize dogs against the H3N2 virus. The vaccine for your dog may not totally prevent the disease; however, records show it provides complete immunity to approximately 90 percent of dogs who receive it.
The vaccine also relieves the severity and duration of the illness. It reduces the period that an infected dog may shed the virus in its respiratory secretions, as well as the amount of virus shed, which makes them less contagious to other dogs. There is some misinformation in the dog care world that the canine influenza vaccine is not effective. That is false information and should be discounted. The USDA has fully licensed all these vaccines.
How Can I Prevent My Dog From Getting Canine Influenza?
Canine influenza is highly contagious, so be aware of other dogs that encounter yours in play areas and walking paths. Family members should wash their hands after petting and playing with other pets.
In times of known disease outbreaks, minimize your dog’s contact with other dogs. Do not share food and water bowls with other dogs. Kennel items, bedding, toys, and dishes should be frequently cleaned and disinfected as the virus can remain infective up to 48 hours on hard surfaces such as counter tops and dishes. Consult with your veterinarian to assess the specific needs of your dog and the environment in which it lives and take all necessary precautions. Prevention is always better than treating the disease once it has been infected.
For further information, visit:
Centers for Disease Control and Prevention at http://www.cdc.gov/flu/canine/index.htm
American Veterinary Medical Association at https://www.avma.org/public/PetCare/Pages/CanineInfluenza.aspx
If you think your dog may be showing symptoms of the flu, find a veterinarian here.