Canine Influenza

Laurie Anne Walden, DVM

Key points

• Canine flu is highly contagious among dogs.
• Symptoms are similar to those of other respiratory infections.
• Illness in most dogs is mild, but some dogs develop more serious disease.
• Most dogs recover with treatment. Fewer than 10% of infected dogs die.
• Mallard Creek Animal Hospital uses a new vaccine that covers both known strains of canine influenza virus. This vaccine requires a booster to provide full protection.

You may have read about canine influenza in the news recently. Cases of canine flu have been confirmed in North Carolina, and 2 dogs have died. Here's what you need to know.

How canine flu spreads
Canine flu is caused by an influenza A virus that is highly contagious among dogs. It spreads through respiratory tract secretions. Sources of infection typically include the following:

• Infected dogs at shelters, kennels, dog shows, dog parks, or other areas where dogs gather
• Contaminated items, such as water bowls used by dogs with canine flu

Two strains of canine influenza virus have been identified in the United States. H3N8 virus was first seen in this country in 2004. H3N2 virus caused an outbreak in the Chicago area in 2015 and the recent cases in Florida and Georgia.

About 80% of dogs exposed to the virus develop clinical signs of infection. About 20% have no symptoms but can still spread the virus to other dogs.

Infected dogs are most contagious during the first 2 to 3 days after infection, before they show signs of illness. Dogs infected with H3N2 virus can continue shedding virus, potentially infecting other dogs, for more than 3 weeks.

Cats can also contract canine flu and spread it to dogs. To date there has been no evidence of the virus infecting humans.

Signs of canine flu
Clinical signs typically appear 2 to 3 days after exposure to the virus. Most signs are similar to those caused by canine infectious tracheobronchitis (kennel cough) and other respiratory infections. The mortality rate is less than 10%.

Most dogs develop mild symptoms:

• Cough (dry or moist)
• Nasal discharge
• Fever
• Decreased activity and appetite

Some dogs develop more severe illness:

• High fever (104°F to 106°F)
• Secondary bacterial infections
• Pneumonia

Diagnosis and treatment
Canine flu is diagnosed by sending swabs or blood samples to a diagnostic laboratory. There is no rapid in-house test for canine influenza virus. However, treatment does not depend on having a definite diagnosis.

As with human influenza, treatment is supportive and depends on the patient's symptoms. Antibiotics do not affect the virus that causes flu. Most dogs have mild illness that resolves after 2 to 3 weeks. Some dogs need treatment for secondary bacterial infections, dehydration, and other problems caused by the virus.

Vaccination
As of June 2017, Mallard Creek Animal Hospital uses a new canine influenza vaccine that covers both strains of the virus.

• The vaccine reduces the severity and duration of symptoms but does not entirely prevent infection.
• We make vaccine recommendations on a case-by-case basis depending on each dog's exposure risk.
• Dogs receiving the flu vaccine for the first time need a booster vaccine 2 to 4 weeks later. The vaccine is then given once a year.
• Dogs that we vaccinated for canine flu before June 2017 also need a booster after receiving the first dose of the new vaccine (the previous vaccine covered only one strain).

What you should do

• You can prevent exposure by keeping your dog away from other dogs. Call us if you'd like to make a vaccination appointment.
• If you think your dog might have flu, call us and limit your dog's contact with other dogs. We will probably ask you to wait with your dog in your car instead of the reception area before your appointment (as we usually do with pets that may have infectious respiratory illnesses).

For more information:

• Canine influenza in North Carolina (NC Dept of Agriculture and Consumer Services)
• Canine Influenza: Know the Facts (NCSU College of Veterinary Medicine)
• Canine Influenza: Pet Owner's Guide (American Veterinary Medical Association)
  

June 15, 2017

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