Canine Influenza Symptoms



TL;DR: There is currently a shortage of canine influenza vaccines.

Paoli Vetcare is recommending prioritizing regular daycare participants and dogs at risk of severe disease or death if they get infected.

Especially if you will be boarding, and your dog is high risk, plan to schedule your dog soon.

High risk categories are detailed below.



We’ve been dealing with a major shortage of canine influenza vaccine for a while. There are a couple of different strains of dog-adapted flu internationally, but currently we’re really just worried about H3N2. This strain is present in Asia and the US (to which it was imported from Asia).

Canine flu is different from human flu in that it’s not particularly seasonal, and it’s not as widely distributed. In the US, we see sporadic cases and outbreaks that seem to jump around the country, often causing local outbreaks that tend to burn out. We saw an unprecedented outbreak of canine respiratory disease in our area during the summer of 2022.

Canine flu causes symptoms of cough, lethargy, lack of appetite, discharge from nose or eyes, and fever that lasts 2 – 3 weeks. No specific therapy is available. We treat a dog only to decrease the symptoms unless pneumonia develops. Most dogs recover, but it can be fatal.

Canine flu vaccines are reasonably good at what they’re designed to do — reduce the likelihood and severity of disease. They’re not meant to stop the spread of the virus altogether, or contain an outbreak. They’re used to reduce severe impacts on dogs that get infected.

The canine flu is highly transmissible — almost all dogs exposed to the virus will get it — and all dogs can benefit from vaccination; but that is not going to happen right now due to the shortage. The initial vaccine protocol is two injections 2 – 4 weeks apart, with an annual booster. A dog is not considered protected until 14 days after the second dose.


High Risk Dogs that Should Be Vaccinated ASAP

Based on the recommendations of Dr. Scott Weese, Chief of Infection Control at the Ontario Veterinary College, we will schedule dogs in the following groups for immediate access to canine influenza vaccination:


✅ ✅ ✅ Regular daycare participants


✅ ✅ ✅ Very young — 6 weeks to 1 year of age


✅ ✅ ✅ Pregnant


✅ ✅ ✅ Immunocompromised:

    • Cancer
    • Diabetes
    • Chronic medications — e.g. apoquel, steroids (prednisone and

      prednisolone), cyclosporine, azathioprine, chlorambucil,

      cyclophosphamide, lomustine (CCNU), mycophenolate, leflunomide

    • Autoimmune disease — e.g. autoimmune hemolytic anemia (AIHA) or

      systemic lupus erythematosus (SLE)

      Underlying heart or lung disease:

    • Heart failure
    • Chronic bronchitis
    • Dilated cardiomyopathy
    • Severe congenital heart defects — e.g. patent ductus arteriosus

      (PDA), pulmonic stenosis, and aortic stenosis

    • Pneumonia
    • Pulmonary fibrosis
    • Pulmonary hypertension
    • Heartworm disease


✅ ✅ ✅ Senior dogs:

    • Small breed dogs (like Chihuahuas or Poodles) are generally considered senior at around 10 to 12 years of age.
    • Medium breed dogs (like Border Collies or Bulldogs) are typically considered senior at around 8 to 10 years of age.
    • Large breed dogs (like German Shepherds or Labradors) are usually considered senior at around 6 to 8 years of age.
    • Giant breed dogs (like Great Danes or Saint Bernards) are generally considered senior at around 5 to 6 years of age.


✅ ✅ ✅ Brachycephalic breeds (smush-faced):

    • English Bulldog
    • French Bulldog
    • Pug
    • Boston Terrier
    • Pekingese
    • Shih Tzu
    • Lhasa Apso
    • Brussels Griffon
    • Japanese Chin
    • Boxer
    • Bullmastiff
    • Affenpinscher
    • Cavalier King Charles Spaniel
    • Dogue de Bordeaux
    • Brussels Griffon
    • Tibetan Spaniel

Dr. Erin Downes VMD

Dr. Erin Downes graduated valedictorian from the University of Pennsylvania School of Veterinary Medicine in 1992. She and her husband, Dr. Jay Rowan are the owners of Paoli Vetcare | Main Line Vet & Animal Hospital.