In The Midst Of An Epidemic: Canine Influenza

Last year, Chicago-based veterinarian Jerry Klein noted, "Something scary is going on with the dogs in the Chicago area.” He was witnessing the beginings of a canine influenza outbreak.

Dog flu is commonly spread at places where dogs socialize, like dog parks. malivoja/iStock/Thinkstock

It’s hard to know you are in the midst of an epidemic when you first start to go through it…

Back in early March of 2015, I posted on my Facebook page, “Something scary is going on with the dogs in the Chicago area.” Our hospital, a 24-hour emergency and critical care facility, is used to seeing a high volume of sick and injured dogs and cats, about 11,000 a year. But what we were seeing last spring was different.

Suddenly, a large number of sick, coughing dogs started arriving at veterinary clinics in the heart of Chicago and on the city’s north side. The majority were initially alert, with some hacking coughing. Most hospitals treated these dogs as “Kennel Cough” or infectious tracheobronchitis patients.

Kennel Cough is a non-technical term used for a syndrome of contagious coughs encompassing various bacteria and/or viral etiologies, such as adenovirus 2, canine parainfluenza, Bordetella and Mycoplasma. It was termed Kennel Cough because of its contagious nature: When one dog came down with a cough, soon the whole kennel would be coughing, not unlike children at school or people becoming ill in the workplace. Most dogs had been routinely treated as out-patients with cough suppressants if the cough was non-productive and, depending on the veterinarian, an antibiotic of choice, such as Clavamox or Doxycycline. The cough usually runs its course in about 10 to 14 days, with owners warned to keep their coughing dogs away from other dogs.

Last spring, many of these dogs returned for further care within a couple of days because they did not show the marked improvement expected. They presented with high fevers (sometimes greater than 105), lethargy, lack of appetite, dehydration from not drinking and labored breathing. After about a week of this, most veterinarians in Chicago started to feel overwhelmed and knew this was not just Kennel Cough!

It Was Canine Influenza Virus

After dozens of cases appeared at hospitals and day care and boarding facilities, it was believed that Canine Influenza Virus had reared its ugly little head again.

Day care and boarding facilities in Chicago require that dogs be up to date on vaccines, including the Bordetella vaccination, which protects against one of the causes of Kennel Cough. Because many of the dogs being treated had been at day care and boarding facilities, were up to date on their vaccines and still coming into area hospitals in such waves and with such severity of illness, we started to be concerned about the emergence of a new vaccine-resistant strain.

Canine Influenza Virus (CIV) has been on the scene for about 10 years, and Chicago is no stranger to it. These initial infections started in racing Greyhounds in an outbreak of a strain believed to have originated in horses years before. This strain of CIV was found to be H3N8 after it was isolated from lung tissue. The outbreak spread through at least nine states, with pockets mostly seen in shelters, boarding hospitals and some veterinary hospitals. In 2008, Chicago and other Midwestern boarding facilities were hit with cases of this influenza virus. Most of these cases were not severe, and shelters and veterinary hospitals seemed to be able to contain it by upgrading their disinfection protocols and ventilation systems. Though a vaccine was made available in 2010, many veterinarians did not include it as part of the required annual vaccination protocol due to the fairly easy containment of the virus and the relatively low mortality rates.

Our hospital, as well as others, implemented strict protocols for dealing with suspected cases of CIV to further prevent spread of the illness. We asked pet owners to wait in their car instead of the lobby, we fully gowned up with disposable coverings before examining and while treating suspected cases, and then each exam room was thoroughly disinfected with a bleach solution and allowed to dry for 10 full minutes before seeing another patient in that room.

What Caused The Outbreak?

As the pattern was not typical, some hospitals began performing respiratory panels to try and determine the causative agent of this contagious infectious respiratory disease (CIRD). On April 12, 2015, Cornell University sent out a memo that CIV was in fact the cause, but a new strain called H3N2 (an Asian flu strain previously seen only in Korea, China and Thailand) was to blame for the recent epidemic. Unlike the H3N8 strain, which originated in horses, this strain had originated in birds and is contagious to dogs and cats.

Because the strain was new to North America, there was no immunity to it, which meant that virtually every dog exposed to it would contract it, though not necessarily become ill. In the end, the vast majority of dogs recovered with supportive care, although we sadly did lose a handful of dogs. Many were treated as outpatients, but a large number also required up to three to five days of hospitalization, especially those developing severe pneumonia.

Merck and Zoetis formulated a vaccine against this new CIV H3N2 strain. The vaccine requires a booster in about two to three weeks after the initial vaccine, with yearly follow-up boosters. Dog owners should talk to their veterinarians about the best vaccine protocol for their dogs, based on their health, lifestyle and other risk factors. As with any disease, the very young and the very old, as well as immunocompromised patients, are at highest risk, but this strain seems much more indiscriminate: Otherwise healthy dogs became ill, and some unfortunately succumb.

Will there be future outbreaks of this H3N2 flu virus? We do not know, although a new map released by Cornell University’s Animal Health Diagnostic Center indicates the H3N2 flu has spread to at least 25 states. A recent report mentions pockets in the Northwest (Oregon, Washington and Montana).

Dogs participating in group activities, such as agility, obedience or conformation, are at high risk for exposure. Dogs at boarding facilities, day care facilities, grooming shops or with professional handlers also pose a high risk of possible exposure. There is a potential for severe economic loss, as complete disinfection is required and quarantine for up to two weeks. The virus can be spread by people and via clothing for up to 48 hours. Dog show judges should exhibit care and hygiene in the examination of dogs.

Canine Influenza Virus At A Glance

WHAT IT IS: A highly contagious virus spread directly from dog to dog, through contaminated objects (toys, bowls, etc.), through the air and clothing.

WHERE IT SPREADS: Commonly spread at kennels, dog parks and day care facilities. The concern of spread at dog shows is unfortunately very real.

SIGNS: Dry, hacking cough similar to Kennel Cough, but these dogs often become systemically ill more quickly. Commonly lethargic, not eating or drinking, with eye and/or nasal discharge. Often, they run a (high) fever.

HOW TO TREAT: If you believe your dog is showing signs of Canine Influenza Virus:

  1. Isolate your dogs from other animals for at least two weeks.
  2. Seek veterinary attention if your dog is lethargic, does not want to eat or drink, if the cough becomes “wet” or productive, or the resting respirations seem fast or labored.
  3. Call ahead to your veterinarian. Due to the fact that CIV is highly contagious, let them know you have a coughing dog before arriving at their hospital, as your veterinarian may implement special intake procedures to help minimize the spread of the disease.
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Dogs · Lifestyle