Canine influenza

Black and brown dog held by person

Canine influenza (sometimes called dog flu) is a highly contagious respiratory disease caused by two type A influenza viruses known to infect dogs.

Dogs of any breed, age, sex, or health status are at risk. Almost all dogs exposed to the virus become infected. Infection can occur at any time of year.

Infection with canine influenza virus has occasionally been diagnosed in cats as well, with cats in animal shelters at highest risk. There is no evidence that people can catch canine influenza.

What are the signs of canine influenza?

The signs of canine influenza are similar to those of canine infectious respiratory disease complex ("kennel cough”):

  • Persistent cough
  • Thick nasal discharge
  • Fever (often 104-105oF)
  • Lethargy
  • Runny eyes
  • Reduced appetite

Most dogs infected with the canine influenza virus have mild illness and recover within two to three weeks, while other dogs might seem perfectly healthy. Still others develop complications such as bacterial pneumonia, resulting in more severe illness. The overall risk of death is considered low—about 1-5% of infected dogs.

If you suspect your dog is ill, contact your veterinarian as well as any training, daycare, or kennel facility your dog has recently visited, and keep your dog separated from other dogs to prevent the virus from spreading.

Cats infected with canine influenza virus may have a runny nose, sneezing, congestion, low energy, discomfort, lip smacking, and drooling.

How is canine influenza spread?

Any setting that brings dogs close together—especially indoor settings—increases the risk of spreading canine influenza and other respiratory diseases. Canine influenza virus mainly spreads from infected dogs to other dogs (or cats) through respiratory droplets and the following routes of exposure:

  • Direct contact, as when dogs lick or nuzzle each other
  • Coughing, sneezing, and barking
  • Contaminated objects like food and water bowls, toys, kennel surfaces, or clothing
  • Skin and clothing of people who have been in contact with infected dogs

Infected dogs can be contagious even if they don’t seem ill, and they can spread the virus for up to four weeks after they were first exposed to it. The virus can survive for one to two days in the environment but is easily killed by common disinfectants.

In areas experiencing an outbreak, dogs at particular risk include those that are boarded and/or mix with other dogs at dog daycare, dog parks, dog shows, and agility events as well as dogs that travel.

How is canine influenza diagnosed?

Your veterinarian may suspect canine influenza based on your dog’s history and lifestyle, whether the virus is known to be circulating in your area, and other factors. Because canine influenza looks a lot like other infectious respiratory illnesses, specific laboratory tests are needed to confirm whether a dog is infected with canine influenza virus. These tests may involve collection of nasal or pharyngeal swabs or blood samples. Your veterinary can let you know if such testing is advisable.

How is canine influenza treated?

Treatment for canine influenza is largely supportive, designed to provide rest, fluids, and nutritional care and keep the dog comfortable. In severe cases involving bacterial pneumonia, antibiotics also may be recommended. Whether treated in the veterinary hospital or at home, dogs with respiratory infection need to be kept isolated from other dogs to prevent disease from spreading. The recommended isolation period for dogs with canine influenza is four weeks after signs first appeared.

How can I protect my dog against canine influenza?

Although vaccines are available to help protect against canine influenza, vaccination generally is recommended only in certain circumstances. Talk to your veterinarian about your dog’s risk of exposure and whether a canine influenza vaccine might be right for your dog.

In addition, these tips can help prevent the spread of canine influenza and other infectious respiratory diseases:

  • If your dog is coughing or sneezing, keep them away from other dogs. Call your veterinarian for their advice, before taking your dog in to be seen.
  • Keep your dog away from obviously sick dogs.
  • Reduce contact with large numbers of unknown dogs.
  • Watch for local alerts. If there’s a canine influenza outbreak in your area, keep your dog away from places where dogs gather until the outbreak is over.
  • Wash your hands after handling any dog and especially after handling a sick dog.
  • Avoid sharing your dog’s bowls, toys, and other items with other dogs outside the home, and keep your dog from using items that other dogs might use, like water bowls.

Good hygiene and infection control practices can reduce the risk of contracting infectious diseases. If you plan to board your dog at a boarding facility, travel with them, or involve them in dog shows, competitions, training classes, or other activities where dogs gather, ask what routine measures they take for infection control and whether respiratory disease has been a problem there. Also ask whether the facility has a plan for isolating dogs that develop signs of respiratory disease and for notifying owners if their dogs have been exposed to dogs with infectious disease.