H3N2 Flu Virus in Dogs

The H3N2 strain of canine influenza was first reported in Asia years ago.  It has made its way across the world and is now affecting many pets in North America.  Symptoms of a dog with flu are similar to humans with the flu.  Symptoms may vary from coughing and runny nose to respiratory distress and development of pneumonia from a secondary bacterial infection.

Diagnostics will include a special cheek or nose swab for influenza testing, blood work and radiographs of the lungs.  Treatment is typically symptomatic as there is no way to treat a virus.  If treated appropriately and quickly, your dog’s prognosis of recovery is good.

Dogs can contract canine influenza which can lead to respiratory distress and even death in the most severe cases.  If your dog is exhibiting any of the symptoms listed below, take him to see his veterinarian.  If he is experiencing respiratory issues, it needs to be treated as a medical emergency.

Symptoms of this condition may include:

• Coughing
• Nasal discharge 
• Ocular discharge
• Fever, which can be mild or severe
• Lack of appetite 
• Lethargy 
• Respiratory distress
• Pneumonia 
• Death 

Types

In regards to the H3N2 strain of dog flu, your dog may contract the mild form or the severe form.  If your dog is suffering the mild form, he may develop a moist cough that can last from 10 to 30 days.  He may also have nasal and ocular discharge along with a fever and lack of appetite.  If your dog is suffering from the severe form, he will have a severely high fever that can range from 104 degrees to 106 degrees. This can lead to organ dysfunction and cognitive dysfunction.  He may also experience difficulty breathing requiring increased respiratory effort and may even develop pneumonia from a secondary bacterial infection.

The H3N2 strain of flu that can affect your dog is believed to have originated as avian influenza, found in birds.  There are other strains of flu that your dog can contract, but currently, the H3N2 strain is the predominant cause of flu illness in dogs.  It can be transferred via direct contact from another dog or aerosolized particles of fluids.  Dogs have a high risk of contracting H3N2 if they frequent dog shows, boarding kennels, shelters, groomers, and other facilities where the animals are in close contact with one another.  Many veterinary hospitals now carry the H3N2 influenza vaccination as a preventative measure.  Discuss with your veterinarian if this vaccination is a good option for your dog’s lifestyle.

If you suspect your dog may have the flu, you should take him to his veterinarian for an evaluation immediately.  Upon arrival, your veterinarian may ask you to wait in your car or even have you come in a back door.  This is due to the fact the H3N2 flu virus is very contagious to other dogs.  Your veterinarian and her staff will want to ensure they do not transfer any germs to other sick animals in the facility.  Do not be afraid or offended if this occurs, your veterinarian is just taking all possible precautions to isolate the virus if your dog does indeed have it.  

She will examine your dog entirely as a whole to note all of his symptoms.  She will want to determine if your dog is suffering influenza symptoms or symptoms of another respiratory illness.  To test if your dog has contracted the virus, your veterinarian will collect a throat or nasal swab from your dog.  Many facilities then send this sample out for diagnostic testing at a specific laboratory as most clinics do not have an in-house analyzer for this illness.  Unfortunately, this test takes several days to get results; however, symptomatic treatment can begin while waiting for the outcome.  Antibodies to the influenza virus can typically be detected as early as 7 days after onset of initial symptoms.  

Additional testing will be performed to evaluate your dog’s health.  Blood work will be recommended to check his internal organ function.  The results will also indicate if your dog is dehydrated and/or if he is experiencing some degree of anemia.  A complete blood count (CBC) and chemistry panel will be completed to provide your veterinarian with this information.

Radiographs will be recommended to check your dog’s lung health, especially if he is having trouble breathing or if he has harsh lung sounds upon auscultation.  The images of his lungs will be taken as a side view and a view from the chest through his back known as VD or ventral-distal.   This will show your veterinarian if there is something in the lungs causing his breathing trouble.

Since the H3N2 influenza is a virus, there is no treatment specifically for it.  However, there is supportive and supplemental treatment your veterinarian can provide in response to your dog’s symptoms.  If your dog is coughing, she may send you with a cough suppressant or expectorant depending on the wetness of your dog’s cough.  If he is not eating much, she may administer an appetite stimulant as well as suggest a high calorie diet that is very palatable to the majority of sick pets. 

If your dog is dehydrated, he will need to receive fluids.  If his hydration status is still acceptable but he is only mildly dehydrated, your veterinarian will administer them as subcutaneous fluids to be absorbed slowly over the next few hours.  If your dog is severely dehydrated, he may need to be hospitalized in order to receive his fluids via intravenous therapy.  A catheter will be placed in one of his front legs and hooked up to an IV line.  Your veterinarian may even choose to add electrolytes and/or vitamins to his fluids depending on his need.

If your dog is experiencing any form of respiratory distress, she may decide to offer him supplemental oxygen.  She will want to keep him in the hospital for treatment and monitoring.  Depending on his need, they type of oxygen therapy may vary.  She may want to place him in an oxygen cage so he gets completely saturated.  A different type of therapy would be placement of a nasal cannula so that he is receiving pure oxygen through his nose.  Or if his need is not severe, she may offer him flow-by oxygen until he catches his breath and returns to a normal breathing rate and effort. 

If she is worried about your dog developing a secondary bacterial infection or pneumonia as a result of his condition, she will prescribe antibiotics for you to give at home.  She may recommend a decongestant in addition to his antibiotic therapy.  The medication will vary depending on your dog’s need.  For example, if his eyes become infected, an eye ointment or drop will be prescribed in addition to a broad spectrum oral antibiotic for treatment systemically.

If your dog is diagnosed with the mild form of canine H3N2 influenza, with proper treatment and rest his prognosis of recovery is good.  He may need rest and medication for weeks to completely overcome the illness, but if cared for properly, he should make a full recovery.  If your dog is diagnosed with the severe form or if he does not receive the care he needs, his prognosis of recovery declines.  If the flu results in pneumonia, it can decrease your dog’s chance of a full recovery, especially if he is very young or old, suffering from an additional illness or if he has some type of autoimmune disease.  

For your dog’s best chance at a full recovery, as soon as he is showing symptoms of illness you need to take him to see his veterinarian.  The sooner his illness gets diagnosed and therefore appropriate treatment started, the better his chances of a full recovery.