Professionals Stress High Morbidity, Low Mortality Aspects of Dog Flu

Amid consumer media reports of a killer dog flu, veterinary professionals say the influenza A virus that jumped from horses to greyhounds and pet dogs can be treated in most cases with supportive therapy. Dozens of dogs from all across the United States have been diagnosed with the dog flu, identified as influenza A subtype H3N8. It has been seen in horses for 40 years, said Cynda Crawford, DVM, PhD, a lead researcher who identified canine flu in racing greyhounds last year. There is no evidence, however, to suggest that racing greyhounds were the first dogs to get the flu. “If my research had focused on the shelter population we may have found the virus there first,” Crawford explained. “I do not want people to think that greyhounds have spread this all over the country.”

On Sept. 26, 2005, Crawford participated in a media briefing with research professionals from the Centers for Disease Control and Prevention (CDC), who represent animal and human health, as well as Edward Dubovi, PhD, director of the virology lab at Cornell University’s Animal Health Diagnostics Center, who identified the canine flu last year. Many of the professionals who participated in the briefing contributed to a scientific paper about canine influenza that was published Sept. 26, 2005, in Science magazine. Dubovi is now testing hundreds of serology samples that have been sent to the lab since the dog flu hit the consumer media airwaves. Instructions on sampling can be obtained online.

The highly contagious nature of the flu, which mimics kennel cough and can become fatal if it progresses to pneumonia from secondary bacterial infections, has prompted concern from professionals across the United States and Canada who are encouraged to use contagious disease protocols when handling dog flu cases. 

Symptoms include a soft cough, thick nasal discharge that resembles distemper, or fever. A cough is the most common symptom though every case is different, which is why Crawford encourages receptionists to ask questions about the reason for a visit when booking appointments to minimize exposure to other dogs.

Flu is Highly Contagious

For Best Friends Kennel in New Jersey, the flu spread to most of the dogs housed there within 10 days. On Aug. 30, 2005, Larry Nieman, DVM, owner of DVM Services Consulting, responded to a call from the kennel about six coughing dogs. Ten days later 88 dogs had been diagnosed with canine influenza. There was a total of 150 dogs there at the time, he said. The kennel, which had recently been built with a state-of-the-art ventilation system, was closed on Sept. 10, 2005, when the first fatality was reported. Nieman helped the company, which owns 42 kennels, send letters to 1,400 veterinarians about what he called the “acute epidemic.” Two out of the 88 dogs died.

Three other kennels in the New York, New Jersey area have reported problems with canine influenza-like symptoms but there are no national figures available on how many kennels have seen cases of canine influenza. The American Boarding Kennel Association has fielded questions from some of its members but it is not tracking how many kennels have reported problems with the flu, said Bill Porter, education coordinator.

From Sept. 7-16, 2005, Kristi Gannon, DVM, DACVIM, saw 18 of the dogs that had been boarded at the Best Friends Kennel, ranging in age from 11 months to 13 years old. Sixteen of the dogs had pneumonia and six tested positive for the flu. There was one fatality. “We didn’t know what we were dealing with at first,” said Gannon, director of emergency critical care services at Oradell Animal Hospital in New Jersey. She assumed that the dogs had kennel cough until she spoke with Nieman and later with Crawford. All of the dogs were seen in isolation rooms but two other dogs that were in the waiting room the same day that the kennel dogs were seen at Oradell later developed the flu, Gannon said.

Canine influenza has not been diagnosed in other companion animals though the CDC plans to initiate tests on ferrets and Crawford said she has tested 10 cats from shelters in Florida and Ohio with severe respiratory disease. All tests have been negative for canine flu, but Crawford has a grant to continue her testing.

The virus transmission from horses to dogs has been attributed to changes in amino acids in the hemagglutinin gene, which confers species specificity, Crawford said. Influenza viruses also affect wild and domestic birds, people, pigs, horses, and a few sea mammals. “Dogs are the newest species to be added to the list of those infected by influenza viruses,” Crawford said.

Special Handling Required

Over the last few weeks, Gannon and her colleagues at Oradell have fielded many calls from concerned clients who want to know if they should have their dogs tested for the flu even if they are not showing signs and have not been to a kennel recently. “We tell our clients that this is just like a cold. You can’t live in fear of it,” Gannon said. She does not encourage serology tests unless dogs are showing signs.

As this issue of NEWStat went to press, the virus had been confirmed in pet dogs in California, Florida, Oregon, Massachusetts, New York, New Jersey and Washington D.C., and hundreds of samples had been sent from almost every state in the United States and from Canada, Crawford said. Approximately 30 to 40 percent of the tests have been positive, she added. Dogs from shelters and owned animals have been diagnosed with the dog flu, she said. Due to its highly contagious nature, Crawford urges receptionists to ask clients about a cough when booking appointments so that precautions can be taken to reduce exposure to other patients. In Florida clinics, dogs that had been adopted from shelters were brought in with what was believed to be kennel cough. That same day about 30 to 40 other dogs were seen at the clinic and some of those dogs later tested positive for canine influenza, Crawford said.

To prevent exposure to other dogs, Crawford urges professionals to wear gloves and scrubs when examining dogs with symptoms of dog flu. These dogs should not be allowed in general waiting rooms and Crawford also suggests using isolation rooms for exams. Management Guidelines for professionals are being drafted by the AVMA in conjunction with the University of Florida, Cornell and the CDC, and will be available online soon.

“There’s always going to be the risk that it will get into the general public,” said Gannon. “Some dogs don’t show any symptoms, except a fever, so it’s not clear cut.” Gannon, who expanded the hospital’s isolation ward to accommodate the dogs with influenza, said that technicians and doctors wear surgical gloves and scrubs when dealing with suspicious cases, and added that technicians have been retrained to gather detailed patient histories to pinpoint high-risk cases. She said that questions include whether the dog has a cough, if a patient has been kenneled, was recently adopted from a shelter, or has been to a dog park recently.

The virus can also be spread through respiratory secretions and viral contamination of inanimate objects like water and food bowls as well as toys. The virus, which has an envelope, is not persistent in the environment and is sensitive to routine disinfectant, Crawford said. “You can clean the virus from the premises; it’s not like parvo.”

In addition to a vaccine, Crawford is hopeful that doctors will soon have a way to identify the virus early to prevent a secondary infection, such as pneumonia. She said that she has spoken with several companies that are interested in creating a diagnostic kit for hospitals that would allow technicians to gather samples and test for canine flu in the same day. She likened it to heartworm and the feline leukemia virus tests, which can be completed in veterinary clinics. “We have a good diagnostic test now but it takes too long,” Crawford said. “It’s retrospective, so by the time we get an answer back to the doctor the dog is almost recovered.”

Canine influenza was first diagnosed in a pet dog in August 2004, and can affect all dogs because there is no naturally acquired immunity, Crawford said. However, several dogs that have been exposed have not gotten sick, Crawford said. An assistant scientist at the University of Florida, Crawford has been working with a company to produce a vaccine for canine influenza but did not give any specifics. She estimates that it may take two to three years to develop and test, due to government regulations and safety measures.

To assist veterinary practices with consumer education, AAHA has published a set of talking points about canine influenza that is available online.