Canine Influenza (Dog Flu) in Dogs

Canine influenza, or dog flu, is a highly contagious acute respiratory illness caused by the canine influenza virus. It's a type of influenza A virus, of which there are two strains currently affecting dogs, H3N2 and H3N8. It can cause a fever, an upper respiratory infection, and even pneumonia.

Dog flu is a newer disease, with the first case diagnosed in 2004. As a result, almost all dogs lack any level of immunity. This viral infection is easily transferred from dog to dog through direct contact, nasal discharge, and through contaminated objects. Around 80% of infected dogs show symptoms.

One dog flu strain, H3N2, has been seen to infect cats, but so far, there has been no evidence that either strain can infect humans. Early detection is key to preventing a secondary infection that can lead to more serious complications. There's no cure for canine flu, and treatment primarily involves supportive care. 

Symptoms of canine influenza can be mild or severe, with the mild form being the most common form. Symptoms are generally seen within 2-3 days of infection. 

The mild form includes:

• A cough persisting for 10 to 21 days
• Wet cough or dry cough, like kennel cough
• Loss of appetite
• Lethargy
• Sneezing
• Eye discharge
• Runny nose
• Thick nasal discharge

Between 10% and 20% of infected dogs develop a secondary bacterial infection, which can cause:

• A high fever (104 F to 106 F)
• Pneumonia
• Increased breathing rate

Types 

All canine influenza is caused by the influenza A virus. There are currently two strains affecting dogs.

• H3N8, which has mutated from an equine influenza strain 
• H3N2, which has mutated from an avian influenza strain

There are several ways for dogs to contract dog flu. It can be spread from infected a dog to a non-infected dog by way of:

• Direct contact
• Nasal or aerosol discharge spread with barking, sneezing or coughing
• Contact with contaminated objects, such as surfaces, food bowls, and leashes
• Infection by people carrying the virus from dog to dog on hands and clothing

Any dog is at risk for catching this viral infection, but some dogs run a higher risk. These include:

• Puppies
• Elderly dogs
• Pregnant dogs
• Immunocompromised dogs
• Dogs that are frequently around lots of other dogs, such as day care centers and grooming salons

This viral infection can lead to complications including secondary bacterial infections, dehydration, pneumonia, or other medical issues. Contact your veterinarian immediately if you suspect your dog has canine influenza.

Testing is needed to definitively diagnose canine influenza, as its symptoms resemble kennel cough and other upper respiratory diseases. Cultures can be taken from the nose or throat in dogs who have been ill less than four days. A blood test is the most accurate way to detect this infection, taken once in the first week of illness, and again 10 to 14 days later. 

An antibody test may be done within seven days after symptoms have surfaced to make a positive diagnosis for canine influenza, since the virus itself can be undetectable. Due to the nature of the time frame for the tests, the next step will be to treat the symptoms before a definite diagnosis of canine influenza is made.

There is no specific treatment for the flu so we provide supportive therapy such as fluids and oxygen therapy, medications, and possibly an overnight stay for observation.

Fluid and Oxygen Therapy

Intravenous (IV) fluids are important to improve circulation, lower body temperature when there is a fever, and prevent dehydration. Oxygen is provided by mask or oxygen chamber if needed.

Medication

Medication may include NSAIDs to lower fever and help with aches and pains and steroids to help with breathing and inflammation (though these two medicines would not be given at the same time). Your vet may administer antimicrobials to fight off secondary bacterial infections. 

Observation 

Your veterinarian will suggest your dog stay at the clinic for observation if your dog is in serious condition or isn't responding well to treatments.

Full recovery from canine influenza usually takes two to three weeks. Your vet may provide you with medication and nutritional supplements to aid recovery. Dog flu is rarely severe and is only lethal in 1% to 5% of cases. 

Ensure you clean your dog's living area to lessen the risk of infection for any other susceptible dogs. Prevention is paramount, especially if there has been an outbreak in your area. Dogs with H3N2 should be isolated for 21 days, while dogs with H3N8 should be isolated for a minimum of seven days. 

If you believe your dog is at risk of contracting canine influenza, you may want to speak with your veterinarian. A single vaccine is now available for both strains. 

The dog flu vaccine isn't a core vaccine, so discuss with your veterinarian your dog's risk of exposure to determine if a vaccine is the best course of action. Vaccines should be given at least two weeks before visiting places where dog interactions are high, such as kennels or dog parks. You should keep your dog at least 20 feet from other cats and dogs if you suspect they have dog flu. 

Vaccines against other respiratory pathogens, such as Bordetella, parainfluenza, and adenovirus, may help to prevent a secondary infection.

Canine influenza can be expensive to treat. If you suspect your dog is at risk, start searching for pet insurance today. Wag!’s pet insurance comparison tool lets you compare plans from leading companies like PetPlan and Embrace. Find the “pawfect” plan for your pet in just a few clicks!