Everything Pet Owners Need to Know About Canine Influenza

Dr. Lydia Hill-Grant
Dec 31
3 min read

Canine influenza, often called dog flu, is a highly contagious respiratory virus that affects dogs of all ages and breeds. Just like humans, pups can catch a flu virus, but their strain is specific to dogs and does not spread to people.

Fortunately, veterinarians now offer a vaccine to help protect dogs from this illness and reduce the severity of disease when outbreaks occur (PetMD)

What Is Canine Influenza?

Canine influenza is caused by influenza A viruses, with two major strains circulating in dogs: H3N8 and H3N2. These viruses initially jumped into dogs from other species, H3N8 from horses and H3N2 from birds, and then adapted to canine hosts (PetMD).

Dogs infected with canine influenza often display symptoms similar to the flu seen in humans, including:

High fever
Dry cough
Runny nose and eye discharge
Sneezing
Lethargy
Loss of appetite (PetMD)

Notably, the cough caused by dog flu typically doesn’t respond to antibiotics and can last between 10 and 21 days. In some infected dogs, the virus can cause pneumonia or other serious complications (PetMD).

Understanding the Canine Influenza Vaccine

The canine influenza vaccine stimulates a dog’s immune system to recognize and respond to the influenza virus. Vaccines are available that target both H3N8 and H3N2 strains, often in a single “bivalent” product that protects against both. These vaccines are inactivated (killed virus) vaccines, meaning they contain no live virus and cannot give dogs the flu (PetMD).

The vaccine is not considered a core vaccine like rabies or distemper, so it’s typically recommended for dogs whose lifestyles put them at higher risk of exposure, such as those that visit:

Dog parks
Doggy daycare or boarding facilities
Grooming salons
Training classes
Dog shows or agility events
Veterinary clinics (PetMD)

Dogs traveling to regions with known canine influenza activity may also benefit from vaccination (PetMD).

How the Vaccine Is Given

Puppies can receive their first canine influenza vaccination as early as 6 weeks of age. The initial series usually consists of two doses, spaced 2–4 weeks apart, followed by annual boosters to maintain immunity (PetMD).

While the vaccine doesn’t guarantee complete prevention of infection, it has been shown to reduce the duration and severity of illness and can decrease the amount of virus a dog sheds if they are exposed. This helps limit the spread among other dogs (PetMD).

Benefits and Safety

Vaccinated dogs generally experience:

Reduced risk of developing clinical disease
Milder symptoms if illness occurs
Lower likelihood of pneumonia and severe complications
Shorter period of virus shedding
Increased safety in social environments where dogs congregate (PetMD)

Most dogs tolerate the vaccine well. Mild side effects, such as soreness at the injection site or temporary lethargy, are possible, and severe allergic reactions are rare (PetMD).

Is It Necessary for Your Dog?

Whether your dog needs the canine influenza vaccine depends on their lifestyle and exposure risk. Dogs that regularly mingle with other dogs or travel to areas with known outbreaks are stronger candidates for vaccination. Conversely, dogs with limited social contact may not require the vaccine. A conversation with your veterinarian can help you decide what’s best for your pet (PetMD).