It’s flu season for people and oh my goodness, I hear about more and more folks with the schneezles/coughing/icky-sick stuff. But what about pets? Is dog flu a problem and do our pet dogs need flu shots? I first wrote about canine influenza back in 2015 when dog flu first hit the news. Has anything changed since then? In a word, yes.

People catch viruses from other people. During the past couple of years, with many activities suspended, we’ve stayed at home and our dogs also became home-bodies. But soon when the weather improves and we’re comfortable mingling, many of our dogs will accompany us on outings. Very young, very old, and immunocompromised dogs have the greatest risk for contracting any infectious illness.

Are Dogs At Risk for Canine Influenza?

Dogs don’t interact with bunches of other dogs every day, the way people expose themselves riding buses or during work and social events. Show dogs and other performance canine athletes, as well as those visiting dog parks, boarding facilities, or daycare risk more exposure by coming in contact with other dogs. Proper vaccinations help protect pets if exposed.

What about dog flu? Back in 2015, a localized outbreak in Chicago affected about a thousand dogs. Since that time, they have identified cases in almost every state. Unlike people, dog flu isn’t seasonal and can happen at any time. Organizations that track the canine influenza virus reported 263 positive H3N2 cases in 15 states in 2024, mostly in northeast states, in California and Florida, and in Texas.

TWO DIFFERENT DOG FLU VIRUSES

Just as with people, there are different kinds of flu that affect dogs. Canine influenza A (H3N8) virus is closely related to a common flu virus found in horses for over 40 years. It’s thought that the virus mutated and became infectious to dogs, with first reported outbreak ten years ago in 2003 in Greyhounds. Today, they considered H3N8 a dog-specific canine flu.

A newer strain caused the Chicago outbreak of dog flu. That was the first appearance of Influenza A H3N2 strain of the virus in North America; however, it was first detected in 2007 in dogs in South Korea.

It’s thought that this a “bird flu” adapted to affect dogs. Canine H3N2 virus has since appeared in China and Thailand where it also can spread to and from cats as well as dogs. However, studies indicate that neither virus transmits well to other companion animal species. Further, it is different from human seasonal H3N2 viruses. There have been no reports of dog-to-human transmission, and it is not considered contagious to people.

HOW DOGS CATCH FLU

Dog flu is highly contagious between dogs, in part because it’s so new and few dogs have immiunity. Up to 90% of dogs exposed to the virus get it–but 10-20% contract the virus but don’t show symptoms. However, about 1 out of every 5 infected dogs suffer severe illness and need hospitalization. Sadly, up to 8% of dogs die from complications of the illness.

The virus spreads through direct contact with bodily fluids—sneezing, coughing, sniffing, licking. That means dog-to-dog contact can spread the virus, or aerosol infection from a sneeze/cough. Dogs also catch dog flu from licking toys after contagious dog has mouthed them. Stress caused by travel, confinement or interaction with strange dogs increases your dog’s susceptibility.

SIGNS OF DOG FLU

Both strains of dog flu can cause high fever, loss of appetite, coughing, nasal discharge, and lethargy. Some dogs develop red or runny eyes, and in most cases, there’s a history of contact with other sick or “carrier” dogs.

• MILD FORM: Dogs with mild symptoms may have a “wet” cough (resembling “kennel cough”) with nasal discharge. In mild cases, these signs last 10 to 30 days and usually go away on their own. Cough suppressants and/or antibiotics may be prescribed if a secondary bacterial infection exists. According to Cornell, some infected dogs won’t show signs at all (some experts say probably 20% are asymptomatic). However, they are still contagious and can spread the disease.
• SEVERE FORM: Symptoms may be more severe in cases caused by the H3N2 virus. Signs may be a high sudden fever (above 104 degrees Fahrenheit), followed by hemorrhagic pneumonia, coughing up blood and difficulty breathing. Illness can be complicated with bacterial pneumonia. Hospitalization with aggressive treatment with antibiotics, fluids are vital. Isolation to protect other dogs from contracting the disease is important.

DIAGNOSING CANINE INFLUENZA

Diagnosis starts with symptoms. If your dog has a cough, runny nose, and lethargy, ask your veterinarian for an exam. Further tests to confirm a diagnosis may include blood tests, or PCR of nasal secretions or lung tissue. Cornell has further information on current tests.

A vaccine (NOBIVAC^® CANINE FLU BIVALENT) is available for protection against both known strains of dog flu. Many boarding and daycare facilities now require this preventive vaccine to protect your dog and others. Your veterinarian will advise you best whether dog flu affects your neck of the woods, and if vaccination is a good idea for your dog.

For more information about dog flu, refer to these links:

• DogFlu.com (details about the disease, and recent outbreaks)
• AKC Do Dogs Need a Flu Shot?
• CDC’s Key Facts about Canine Influenza 
• The American Veterinary Medical Association (AVMA) Canine Influenza FAQ

What About Bird Flu?

Yes, avian flu has been in the news, and I’ve delayed writing about it until I learn more. Later today, I attend a “virtual” Zoom meeting with specialists and hope to learn what to pass on to help keep our pets (and ourselves) safe–especially cats, which appear to be most susceptible.