Gracie the Boston Terrier bounced around an examination room during a recent visit to Blum Animal Hospital in Chicago. Down the hall, an ailing Cocker Spaniel endured treatment with a nebulizer.
Both dogs were among the victims of an outbreak of canine influenza ongoing as of late April in the Chicago area.
The scope and nature of the outbreak caught dog owners and veterinarians off-guard. By mid-April, the Cook County Department of Animal and Rabies Control had officially tallied six deaths and more than 1,000 cases of canine infectious respiratory disease in the Chicago area.
Earlier that month, Cornell University and the University of Wisconsin-Madison announced that the outbreak had been caused by an influenza A H3N2 virus from Asia not previously detected in North America, rather than the H3N8 strain that has been circulating in the United States since 2004. It is not known if the current vaccine against H3N8 provides any protection against H3N2.
Jean Miller, Gracie’s owner, was on a cruise in late March when she got a call on a Thursday toward the end of the trip saying her dog might have canine influenza. Gracie was being boarded at the same facility where she goes for day care. The dog had been coughing and had nose drainage, then stopped eating and became lethargic.
“She went from not so sick to very sick pretty quick,” Miller said. “I was extremely worried.”
On Friday, the staff of the boarding facility took Gracie to her veterinarian, Dr. Natalie Marks, co-owner of Blum Animal Hospital. Dr. Marks reported to Miller that Gracie had developed pneumonia, and the veterinarian wanted to admit the dog. Miller agreed, feeling a partial sense of relief because her relatives all have dogs and wouldn’t have been able to take in Gracie.;
“I called on Saturday, and they said she was stable,” Miller said. “Then I wasn’t able to call on Sunday, so I still worried. But when I called on Monday, before I got on the plane to come back, they said that she was doing much better.”
Miller got home late Monday and took Gracie home on Tuesday with three medications and a lingering cough. The day care had closed because of the outbreak, but staff came to walk Gracie each day.
Blum Animal Hospital
In March, Dr. Marks said, Blum and some of the surrounding hospitals noticed an increase in the number of dogs with a respiratory disease that didn’t seem like the usual kennel cough.
Dr. Marks said, “These cases had high fevers. It was a very intense, almost guttural, honking cough. These dogs weren’t eating. They were very lethargic.”
The patients all seemed to have frequented communal dog areas such as day care facilities, boarding facilities, dog parks, groomers, or dog beaches. Then Blum learned of a confirmation of canine influenza in the city and went into high alert.
Members of the practice team set up an isolation unit for patients and started using personal protective equipment. Owners of dogs that might have contracted canine influenza waited in cars instead of the reception area. Blum started working with Cornell to submit samples.
From late March through early April, the hospital was seeing five to 15 cases of canine influenza per day.
“We have all been working tirelessly,” Dr. Marks said. “We have been educating our clients and the community and working with other veterinary practices, the university, the government, trying to just help in any way we can.”
By mid-April, the caseload seemed to be slowing slightly at Blum, but cases had been reported in surrounding states. Dr. Marks expressed concern that there are really no borders for interstate dog travel, and she wants other veterinarians not to be caught off-guard.
Dr. Donna Alexander, administrator of the Cook County Department of Animal and Rabies Control, said the county saw an increase in cases of what people were calling kennel cough starting in January. These cases were more severe, though. The county encouraged veterinarians to send in samples for PCR assays, and the cause turned out to be canine influenza.
The county put out questionnaires asking veterinarians to report canine infectious respiratory disease cases. Some veterinarians reported an increase but did not provide specific numbers. By mid-April, the county had identified at least 1,137 cases. The most severe cases were in dogs under 1 year old or over 7 years old and immunocompromised dogs.
The outbreak seemed to have dwindled as of late April, Dr. Alexander said. She credited veterinarians’ efforts and the closing of many communal dog areas. Frank Shuftan, Cook County public information officer, added that the press was extremely cooperative in getting messages out to dog owners.
“We have had outbreaks of different diseases, but nothing as extensive as this one or as unfamiliar to us as this one has been,” Dr. Alexander said. “This particular canine influenza sort of took us aback because we did not know what we were dealing with.”
Across the country
Among the researchers who identified the H3N8 virus in 2004 was Dr. Cynda Crawford of the University of Florida College of Veterinary Medicine. The strain arose from horses.
Dr. Crawford said H3N8 infected thousands of racing Greyhounds at several tracks in 2005 and 2006. 2011 was a bad year among pet dogs, with the strain infecting pet dogs in 17 states. Dr. Crawford characterized the 2011 outbreaks as epidemics in six states, particularly Texas. Some veterinary clinics in the six states were seeing 30 or more cases daily. The H3N8 strain now has reached 40 states.
“I think the true number of canine flu cases is very underestimated because the clinical presentation looks like the typical kennel cough initially, and many veterinarians or owners will not elect diagnostic testing to determine what is the cause of the acute-onset respiratory infection,” Dr. Crawford said.
She said the Chicago outbreak, albeit the H3N2 strain, is one of the largest U.S. epidemics of canine influenza to date.
Resources on canine influenza are available from the AVMA here.