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Veterinary Public Health Program
313 N Figueroa St. Rm 1127
Los Angeles, CA 90012
Tel (213) 989-7060
Fax (213) 481-2375
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H3N2 canine influenza in Los Angeles County, 2017


VETERINARIANS - Please report cases of Canine Influenza herepdf icon 12432

Download our H3N2 Canine Influenza handout - Englishpdf icon 1243 Españolpdf icon 1243Esp


8.21.17 Scroll down to read about the third cluster of canine influenza H3N2 reported this year.

3 dogs


First Cluster of 2017

In March 2017, canine influenza H3N2 was identified in dogs in Los Angeles (LA) County. Most of the dogs were imported from Asia and seen by a veterinarian after arrival into LA County. The dogs showed signs consistent with influenza such as coughing, sneezing, fever and nasal discharge. Testing of two dogs revealed a strain of canine influenza H3N2 commonly found in Asia.


After investigation, a total of 52 dogs exposed to the virus were identified, including 35 sick animals. Of the 35 sick dogs, H3N2 canine influenza was confirmed by laboratory testing (PCR) in 6 dogs and the remainder of the sick dogs (29) were suspected to also harbor the virus based on symptoms. A total of 62 dogs were placed under quarantine or isolation in 17 locations. The 62 dogs included the 35 sick dogs, plus 17 that were exposed but did not become sick, plus 10 that were living with the exposed but healthy dogs.


Two sick dogs died, however both were suffering from other unrelated illnesses. Ultimately, all of the other sick dogs have recovered and were released from isolation. Samples from several dogs were submitted to veterinary virologists in order to compare this virus to the canine influenza H3N2 virus that caused a large outbreak in the Chicago area in 2015.


Canine influenza H3N2 usually causes mild to moderate disease in dogs and on rare occasions can also infect cats. This strain of canine influenza was first found in the US in 2015 when it emerged in Chicago and spread to other parts of the country. Infected dogs start shedding the the virus 2 days before the start of clinical signs, and for at least 21 days afterward, even after they appear healthy. Transmission of influenza usually occurs through contact with infected respiratory secretions (e.g. coughing, sneezing) as well as from contamination of the environment (e.g. bedding, floors, bowls, collars, leashes).


To date, there is no evidence that humans can become sick with
canine influenza H3N2 .


Response from the Department

The Veterinary Public Health Program (VPH) is providing assistance during this outbreak by:

  1. Enforcing quarantine of all affected dogs to prevent spread of the disease locally.

  2. Alerting veterinarians in LA County of the outbreak through the
    Animal Health Alert Network (AHAN).

  3. Supporting local veterinarians and affected parties by coordinating response.

Second cluster of 2017

On April 11, 2017 VPH was notified of an unrelated case of a dog positive for H3N2 canine influenza in early March, pre-dating the importation of the sick dogs from Asia. This animal had been ill very early in March when it was brought from San Bernardino County into LA County. The dog was kept in isolation for 2 weeks before being placed in a facility with a large group of dogs.


Because dogs infected with canine influenza H3N2 can sometimes be contagious for 3 weeks or longer, VPH worked closely with the facility to check for further spread of the virus. No additional cases were found.

Very few of the dogs in the facility were coughing, suggesting that influenza was unlikely to have been on site. VPH tested 10 of the 91 dogs in the facility for influenza by PCR - all 10 were negative.  VPH worked to track down the 79 dogs that had left the facility in March and April in order to further check for evidence of spread. A total of 69 were successfully located. Most were healthy, but 14 had had some coughing. Three of the 14 were serologically tested for exposure to canine influenza H3N2 and were negative, showing they had not had influenza. 


Third cluster of 2017

On August 3, 2017, Veterinary Public Health (VPH) was notified that a dog living in the San Gabriel Valley tested positive for canine influenza H3N2 by PCR. The dog developed a cough on July 29th after boarding at a local kennel. The veterinarian tested the dog for influenza when seen on July 31st, even though the symptoms were mild.


VPH has been actively investigating this cluster of cases by:

  • Contacting owners of dogs that were at the facility since mid-July to identify additional potential cases and institute quarantines to reduce disease spread

  • Quarantining ill dogs at their homes for 40 days after onset, since dogs infected with this virus may potentially be contagious for 30 days or longer (unpublished data)

  • Quarantining at home any healthy animals that were exposed to the sick dogs  for 14 days after last potential exposure

At least 26 other dogs developed respiratory-like illness after being at the facility during the last half of July    through the first week of August. Three dogs that were at the facility and had a respiratory-like illness were tested for canine influenza by PCR and all three tested negative. The source of this outbreak is unknown.


 Impact of this virus

While the H3N2 strain of canine influenza causes a mild disease, many dogs in Los Angeles County may be susceptible to this virus because of lack of previous immunity. As of now, the spread of canine influenza H3N2 appears to be contained locally, however an uncontrolled outbreak may lead to thousand sick dogs. This can have a significant impact in dogs awaiting adoption in animal shelters. One of the most effective tools to reduce the number of  dogs sick with this disease is to vaccinate them against canine influenza H3N2 .



Pet owners

  • If you think your pet has influenza, keep it away from other animals and contact your veterinarian.

  • Pets that frequently interact with other dogs (e.g. dog park, groomer, daycare) should be vaccinated against canine influenza H3N2.

  • To prevent spread of disease, do not let a sick pet share its food bowl, leash, toys or other supplies with other pets.

  • Wash your hands after touching your pet.


Veterinarians/Animal workers

  • Do not allow coughing dogs into your lobby. Move them immediately into an exam room, or (if it is not hot outside) have the owner wait in the car with their coughing dog.

  • In any case with a coughing dog, ask about the health of dogs that spend time near the coughing dog, to determine if there may be an outbreak. Advise the owner to keep the coughing dog at home.

  • Report any suspected or confirmed case of influenza in dogs or cats to VPH using this reporting formpdf icon 12432.

  • If a case is suspected, use proper isolation measures to prevent infection via direct contact or fomites.

  • Recommendations for disinfection and biosecurity available here.


More Information

Canine Influenza - Los Angeles County Department of Public Health

Canine influenza (Dog Flu) - Centers for Disease Control and Prevention (CDC)

Canine Influenza - American Veterinary Medical Association (AVMA)

Canine Influenza H3N2 Updates - Cornell University Animal Health Diagnostic Center


Last updated: August 11, 2017

Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.
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