By Dr. Jean Hofve, DVM, Veterinarian Advisor
Can Dogs Catch the Flu?
Canine flu is a contagious respiratory disease in dogs. It is thought to be a mainly airborne virus, most likely transmitted by an infected dog coughing or sneezing on another. In otherwise healthy dogs, statistics show that the canine flu is a fairly mild disease with most dogs recovering completely in two to three weeks.
The canine influenza virus (CIV), type H3N8, was first noted in greyhounds several years ago, and appeared quite dangerous at the time, with many deaths. However, its deadly effects are attributed to secondary pneumonia that developed due to the unsanitary conditions in which the greyhounds lived and worked.
What is the Difference Between H3N8 and H3N2?
In March 2015, a new outbreak began in Chicago and quickly spread around the Midwest; other areas have also reported cases. This is a different strain, H3N2, that originated in Asia. This form of CIV appears to be generally mild, except in susceptible individuals, including young puppies. This strain is also unusual in that it can affect cats and possibly other animals, though not humans.
What are Canine Influenza Virus Symptoms?
In the vast majority of dogs, CIV produces only mild, self-limiting respiratory signs: coughing, sneezing, runny nose, and fever, for up to 3 weeks. In some cases, lethargy and poor appetite may develop. Canine flu is similar to kennel cough in that antibiotics do not affect the course of the disease.
The canine flu is highly contagious; and like human flu, it is most contagious during the 2-4 day incubation period before signs of illness appear. Infected dogs continue to shed virus for about 10 days. These traits make prevention difficult.
The most likely places for your dog (or cat) to contract this flu virus are daycare and boarding kennels, dog parks, grooming facilities, pet stores, and veterinary clinics – all places where a lot of animals (especially puppies) pass through, and the chances of spreading the virus are high.
Is There a Vaccine for Canine Influenza Virus
A vaccine against the H3N8 strain of CIV is available. However, again, like human flu vaccines, it neither prevents infection nor prevents symptoms. At best, it may reduce the severity and duration of illness, and it may reduce viral shedding by an infected dog. Because it is a killed vaccine, a 2-shot series is required, with at least 10-14 days between inoculations. Immunity develops slowly; so the vaccine doesn’t really take effect until 3-4 weeks after the first shot. Giving the vaccine after a dog has been exposed to the virus is therefore useless.
IMPORTANT NOTE: The currently available vaccine does not protect against the H3N2 strain that is going around in 2015.
The CIV vaccine is considered non-core, and vaccination is not recommended for most dogs; or for any dogs that may be exposed to the newer, H3N2 strain. Some boarding kennels require vaccination for CIV; however, such requirements are not based on science, but on fear.
How is the Canine Influenza Virus Spread?
CIV spreads through respiratory secretions and contaminated objects (kennel surfaces, food and water bowls, collars and leashes), and by people moving between infected and uninfected dogs without using proper precautions.
The virus can remain infectious on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours. Good hygiene and isolation of infected dogs will limit, if not eliminate, transmission.
What Dogs Does the Canine Influenza Affect?
CIV, like many other viruses, is most likely to cause serious problems in young puppies, and in older dogs who already have other health issues.
What is the Best Defense Against Canine Influenza?
The best defense against canine flu (or any other infectious disease) is a healthy immune system — that is, one that is supported with top quality nutrition, appropriate supplements (antioxidants, Omega-3 fatty acids, and other immune supporters), limiting exposure, appropriate exercise, and good stress management.