FIRST THERE WAS H3N8
Canine Influenza virus was first reported in Florida in 2004. This strain was labelled H3N8. H3N8 probably “jumped species” into the canine population from horses. At that time H3N8 caused a few isolated outbreaks in Los Angeles county. There is a vaccine available to help protect dogs from getting sick from H3N8.
THEN CAME H3N2
You will recall that in March of 2015, Chicago-area veterinarians saw a significant number of dogs with respiratory disease that turned out to be a new strain of the Canine Influenza virus called H3N2. Until that time, North America had only hosted the H3N8 strain of the Canine Influenza virus, for which there is a vaccine. Later, in July 2015, the first confirmed case of H3N2 in Los Angeles county appeared in a single adult Labrador mix dog. He was treated. At that time there was no vaccination for H3N2 and it was unclear if the H3N8 vaccine would provide any cross-protection to H3N2 - DTLAvets did not recommend empirical H3N8 vaccination for dogs then.
According to the Los Angeles County Department of Public Health, in March 2017, H3N2 was identified in several dogs living in Los Angeles county. Most of these dogs were imported from Asia and arrived to Los Angeles county demonstrating respiratory signs like coughing, sneezing, fever and nasal discharge. Twenty-seven ill dogs were identified and treated with supportive care - the majority of them recovered. Testing among that population of dogs revealed the H3N2 strain of Canine Influenza virus.
As of April 7, 2017, an additional five dogs have tested positive for H3N2 in Los Angeles county. These sick dogs as well as healthy but exposed dogs are currently under quarantine or isolation around Los Angeles county. To date there are no cases reported outside of these locations.
HOW IT’S SPREAD
Infected dogs start shedding the virus 2 days before the start of clinical signs and for 21 days or longer afterwards. Transmission usually occurs through contact with infected respiratory secretions (droplets from coughing or sneezing) as well as from contamination of the environment (bedding, floors, bowls, collars, leashes).
TO DATE THERE IS NO EVIDENCE THAT HUMANS CAN BECOME SICK WITH EITHER THE H3N2 OR H3N8 STRAINS OF CANINE INFLUENZA
H3N2 usually causes mild disease in dogs - it rarely infects cats. Fever, lethargy, coughing, sneezing, poor appetite and nasal discharge are the most common signs of either strain of Canine Influenza, but some dogs may not show any symptoms. While pneumonia and even death can result from infection with either strain, this outcome is rare. Most dogs with Canine Influenza recover in 2-3 weeks with supportive care.
OUR UPDATED RECOMMENDATION: VACCINATE FOR H3N2
DTLAvets is now recommending that dogs who spend a significant amount of time at dog parks, in doggy daycare, at grooming or boarding facilities, or those dogs traveling to or from Asia should be vaccinated for the H3N2 strain of the Canine Influenza virus. If this is the first time that a dog is vaccinated for H3N2, it must be boostered in 2-3 weeks, then given annually thereafter or until recommendations change. The risks of the H3N2 vaccine are similar to any other core canine vaccine. While most dogs handle the vaccine without any side effects, some dogs some may experience lethargy or itchiness/sensitivity at the site of the injection. These are usually transient signs and the benefits of vaccination outweigh these passing side effects. However as with any vaccination, there is a very small chance that a more dramatic reaction can occur. These reactions may include swelling of the eyelids or muzzle, hives, vomiting and/or diarrhea. Should these signs develop, you should immediately take your pet to your closest veterinarian. In these dogs, the risks of vaccination may not be outweighed by the benefits and these dogs should be very cautious about socializing in high-density dog areas.
DTLAvets doctors and staff are happy to answer your questions regarding this emerging virus. We are accepting appointments for vaccination with the Canine Influenza (H3N2) vaccine after Friday, April 14th.
Reliable Informative Sources for more information about Canine Influenza:
1. Los Angeles County Department of Public Health
2. California Veterinary Medical Association