Dog Flu Symptoms: What to Look For

By Kellie B. Gormly

Your dog is coughing and congested, listless and feeling lousy – just like we feel when we come down with a respiratory ailment.

Could your dog have the canine version of the common human bug known as influenza? The answer is yes—and it is important to get a prompt evaluation, says Dr. Brian Collins, section chief and lecturer of Cornell University College of Veterinary Medicine’s Community Practice Service in Ithaca, N.Y.

Like in humans, influenza is a respiratory disease, Collins says. Since most dogs have no natural immunity to these relatively new viruses, many who are exposed to Canine Influenza Virus (CIV) will become sick. That is the bad news. The good news is that most dogs who get sick from the canine flu have only a mild form of the disease.

Dog Flu Symptoms

Dogs that come down with a mild form of the flu will display a fever and cough that will last one to three weeks, Collins says. Other early symptoms can include decreased appetite, lethargy and a greenish discharge from the nose and eyes.

Unfortunately, some dogs get sicker than this and develop a higher fever and labored breathing from pneumonia. For some, Collins says, the flu becomes fatal.

Diagnosis can be tricky because the canine flu symptoms mimic those of the more common kennel cough and other, potentially more serious ailments like pneumonia, heart disease, or even some types of cancer. It is important for pet parents to take dogs for a medical exam, Collins says.

“I would caution dog owners from trying to diagnose their dogs prior to consulting their veterinarian,” Collins says. “Because clinical signs of canine influenza can overlap with numerous other conditions, dog owners should contact their vet whenever they observe anything abnormal with their pet.”

What Causes the Dog Flu?

Two separate viruses can cause the canine flu, Collins says.

The first, H3N8, was identified as a contagious dog disease in 2004, according to Cornell’s web page on the subject. Researchers at Cornell’s Animal Health Diagnostic Center isolated the virus, in conjunction with a University of Florida research project on respiratory disease in racing greyhounds.

The virus was sequenced at the Centers for Disease Control, and researchers determined the virus was related to the H3N8 equine virus that was circulating among American horses. Within a year of the dog virus’ discovery, some pet dogs in Florida and New York City had the virus. Since then, the virus has appeared in many different areas of the United States, according to Cornell.

But another type of flu virus—H3N2, of bird origin—can also cause the dog flu. This virus first appeared in 2015 in the Chicago area and spread quickly to many states. The H3N2 virus, which also appeared in some cats, is the one causing the most concern in the pet community now, Collins says.

Dog Flu Treatment Options

Treatment for canine flu varies. For mild cases, the vet may simply encourage rest, home monitoring of the dog, and maybe changes in food and water intake, Collins says. If the coughing is more severe, the doctor may prescribe cough suppressants, and antibiotics if the dog has a secondary bacterial infection.

Dogs who are severely ill with CIV may require hospitalization for intensive care that includes intravenous fluids, antibiotics and oxygen therapy. Sadly, a small percentage of dogs still will die from the flu despite treatment, Collins says.

There are vaccinations available to help safeguard dogs from severe disease caused by flu viruses. However, with more than one strain in widespread circulation, dogs need both H3N2 and H3N8 vaccines to ensure protection against both flu versions, Collins says. If your dog hasn’t been vaccinated and your vet recommends it, he will receive a set of two shots, given two to four weeks apart, followed by annual boosters.

Vaccines now are given to dogs at a higher risk of catching the flu, such as dogs that go to kennels and dog shows. Dogs that are exposed to many other dogs and canines in outbreak areas are also considered prime candidates for vaccinations, Collins says.

Can Dogs Transfer the Flu Virus to Humans?

Since we humans get the flu too, can our dogs transmit the disease to us? At this point, Collins says, there is no evidence the canine flu is zoonotic and contagious to people.

“However, there is the potential for the virus to change over time such that it could jump species, including to people,” he says. “The CDC is monitoring this threat.”

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