What is Flu?
There are two strains of dog flu in the United States, which include H3N8 and H3N2. The most recent was the 2016 outbreak of H3N2 in the Midwest that started as a bird flu in Asia. This strain is thought to be spreading throughout the United States. Being in close quarters with infected dogs is enough to spread the virus because it is airborne and can be spread through sneezing, coughing, and even barking. Unfortunately, the time when the virus is most contagious is during the incubation period when there are no symptoms of illness.
The flu (canine influenza) is common in dogs that spend time in dog parks, shelters, or kennels. In fact, if you work in a veterinary office, kennel, or shelter, you can also bring home the flu to your dog. The flu is spread through bodily fluids; water and food bowls, bedding, and close contact. Dogs are most contagious during the three or four-day incubation period. Most of the time, the infection is mild and only includes a cough, sneezing, high body temperature, and lack of appetite. In rare cases (less than 10%) the flu can be fatal, with a body temperature of over 104 degrees Fahrenheit, secondary bacterial infection, and pneumonia. If your dog is showing any of these symptoms, you should call your veterinarian as soon as you can.
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Symptoms of Flu in Dogs
The symptoms of the dog flu vary depending on whether your dog’s case is mild or severe. In mild cases, the most common signs include:
- Increased body temperature up to 103 degrees Fahrenheit
- Sneezing and runny nose (clear at first, changing to greenish-yellow)
- Watery eyes
- Appetite loss
If your dog’s flu becomes severe, the symptoms will also include:
- Extremely high body temperature over 104 degrees Fahrenheit
- Extreme lethargy
- Rapid heart rate
- Breathing trouble
- H3N8 started as an equine virus but jumped from horses to dogs in 2004
- H3N2 started in South Korea as a bird flu in 2007 and jumped from birds to dogs in 2015
Causes of Flu in Dogs
There are many ways that dogs can contract dog flu, but being in close contact with many dogs is the biggest risk such as:
- Dog parks
- Veterinarian’s office or pet hospital
Diagnosis of Flu in Dogs
Diagnosing dog flu is done with a hemagglutination inhibition influenza virus test for antibodies. This test is repeated in 10 to 14 days to confirm. To determine the strain of the virus, the veterinarian will send a nasal swab to a laboratory for a polymerase chain reaction (PCR) test that can verify that your dog has the flu and what strain it is. It may take several days to get the results, so the veterinarian will give you a tentative diagnosis by ruling out other conditions such as kennel cough and bronchitis. The first thing needed is a complete and thorough physical examination including vital signs, palpation, and auscultation. Also, be sure to tell your veterinarian if you have given your dog any medication and describe the symptoms that you have noticed. Some important laboratory tests include a urinalysis, fecal examination, and blood tests such as a complete blood count (CBC) and chemical analysis. The blood count will likely show increased white blood cells (neutrophils) and the chemical analysis may reveal an abnormal packed cell volume (PCV).
The veterinarian may use a bronchoscope to check the trachea and bronchi for inflammation and abnormal secretions. Samples are taken by swabbing the throat or using a bronchial wash or lavage. These samples will be examined under a microscope as well. In addition, chest x-rays are important to look for any signs of secondary infection or pneumonia. The veterinarian may get a CT scan, MRI, or ultrasound if needed.
Treatment of Flu in Dogs
There is no cure for the flu so the only treatments are supportive therapy such as fluids and oxygen therapy, medications, and possibly a hospital stay for observation.
Fluid and Oxygen Therapy
Intravenous (IV) fluids are important to improve circulation, lower body temperature, and prevent dehydration. Oxygen is provided by mask or cannula if it is needed.
Medication may include NSAIDs to lower fever and help with aches and pains, antibiotics to prevent secondary infections, and steroids to help with breathing and inflammation.
If your dog is in serious condition or is not responding well to treatments, the veterinarian will probably suggest a short hospital stay for 24-hour observation.
Recovery of Flu in Dogs
The death rate for the flu is less than 10% overall. Unless your dog has complications from pneumonia or secondary infections, he should recover completely within two to three weeks. Be sure to follow up with your veterinarian as instructed.