|H3N2 canine influenza in Los Angeles County, 2017
- Please report cases of
Download our H3N2 Canine
Influenza handout -
down to read about the third cluster of canine influenza
H3N2 reported this year.
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.
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
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 .
The Veterinary Public Health Program (VPH) is
providing assistance during this outbreak by:
Enforcing quarantine of
all affected dogs to prevent spread of the
Alerting veterinarians in
LA County of the outbreak through the
Health Alert Network (AHAN).
veterinarians and affected parties by
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.
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
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
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
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
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
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.
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
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
Report any suspected or
of influenza in dogs or cats to VPH using
this reporting form.
If a case is suspected,
use proper isolation measures to prevent
infection via direct contact or fomites.
disinfection and biosecurity available
Canine Influenza - Los Angeles County Department of Public
Canine influenza (Dog Flu) - Centers for Disease Control and
Canine Influenza - American Veterinary Medical Association
Canine Influenza H3N2 Updates - Cornell University Animal
Health Diagnostic Center
Last updated: August 11, 2017