Canine influenza made headlines in 2015 when a relatively new virus strain, H3N2, emerged in Chicago and spread nationwide, infecting thousands of dogs and killing a small number.
The fact that drug manufacturers quickly released H3N2 vaccines should not minimize the threat that influenza poses to large numbers of dogs. Eileen Ball, DVM, MPH, Dipl. ACVPM, senior manager of U.S. Companion Animal Veterinary Specialty Operations at Zoetis Inc., urges veterinarians to remain vigilant.
“They need to have a plan in place for dealing with dogs that are suspected of having an infectious disease,” said Dr. Ball, who spent several years in clinical practice.
Veterinary hospitals, she said, should have policies for determining where sick dogs enter the clinic—if they are admitted at all—how patients are handled from a biosecurity standpoint and how noninfected patients are protected.
H3N2 existed in Southeast Asia for years, but alarms sounded in the United States in March 2015 when Chicago-area dogs began coming down with the highly contagious disease.
Fortunately, vaccine manufacturers were prepared.
Zoetis acted quickly, cutting through red tape to bring Vanguard CIV H3N2 to market by the fall.
“We had a vaccine in veterinarians’ refrigerators by the end of November,” Ball said.
Should a new canine flu strain arise, manufacturers are ready, said Madeleine Stahl, DVM, associate director of scientific marketing affairs in the Companion Animal Division of Merck Animal Health.
The drug maker released an H3N2 vaccine days after New Jersey neighbor Zoetis did.
“We offer a full complement of monovalent CIV H3N2 and H3N8 vaccines, as well as the first bivalent canine influenza vaccine, Nobivac Canine Flu Bivalent,” Dr. Stahl said. “The bivalent canine influenza vaccine is more convenient, means fewer injections for the patient, can be more cost effective for the owner and translates to a lower inventory in the clinic.”
Experts want to allay fears in the veterinary community about future outbreaks of dog flu.
“Availability of these vaccines means that manufacturers are better prepared for the next outbreak, provided it is caused by the same strain,” said Jeremiah T. Saliki, DVM, Ph.D., Dipl. ACVM, director of the Athens Veterinary Diagnostic Laboratory at the University of Georgia.
Deborah Silverstein, DVM, Dipl. ACVECC, an associate professor of critical care at the University of Pennsylvania School of Veterinary Medicine, said veterinary professionals are more aware and better prepared in 2017.
“Keep in mind, the vaccine does not prevent disease completely but does seem to reduce the severity of disease in vaccinated dogs,” Dr. Silverstein said. “There are two vaccines, one for the original H3N8 virus and a newer one for the H3N2 virus, as well as a new combined vaccine with both strains.
“They are killed vaccines,” she said, “and both require two doses to develop a protective immune response. Neither is approved for use in cats.”
Dr. Saliki hedged his optimism with a note of caution, since influenza vaccines are strain-specific.
“It is well known that new strains of influenza virus emerge frequently, which means vaccine manufacturers have to be prepared to formulate new vaccines,” he said. “It is difficult to determine if the next canine outbreak will be caused by H3N2 or yet another strain.”
What to Do
Merck’s Stahl suggested that veterinarians implement vaccination protocols covering both canine strains for at-risk dogs.
“While the H3N2 strain has received the most media attention in the past year, canine influenza H3N8 has not gone away,” Stahl said. “Continued surveillance has found the H3N8 strain in 42 states. The most recently added state was Montana, when H3N8 was identified in July 2016.
“Furthermore,” Stahl added, “the H3N2 strain has spread to at least 30 states since March 2015. Because influenza viruses are highly unpredictable and spread rapidly, vaccination against both strains is recommended.”
The importance of vigilance was shared by all the experts.
“I don’t think the threat is over,” Zoetis’ Ball said.
Her top concern: Just because vaccines are available doesn’t mean all dogs are receiving them.
“With a novel virus like CIV H3N2, basically our entire canine population is going to be naive to that virus,” Ball said. “Viruses can get into dogs, and they just spread like wildfire.”
Heather Loenser, DVM, a veterinary adviser with the American Animal Hospital Association, echoed those thoughts.
“Just because the vaccines exist doesn’t mean that the dogs at risk will receive them,” Dr. Loenser said. “Veterinary teams should educate caretakers on the importance of these vaccines if dogs spend time in higher risk environments, including boarding and day-care facilities, shelters, competitions and dog parks.
“Vaccinated dogs may still become infected following exposure, may develop mild clinical signs and may transiently shed virulent virus,” Loenser said.
Additional recommendations are in AAHA’s 2011 Canine Vaccine Guidelines, found here.
Updated guidelines are expected to be available this year.
Spreading the Word
Aside from the importance of providing broad protection against H3N2 and H3N8, client communication is key, Stahl said.
“As long as there are unvaccinated socially active dogs, the threat of canine influenza infection will persist,” she said. “Veterinarians can help educate pet owners about the factors that put dogs at risk and the importance of prevention through vaccination.”
Merck has been sharing information with veterinarians about canine influenza, the importance of vaccinations and the need to tell pet owners about precautionary measures they can take. More on the educational outreach is available at www.doginfluenza.com.
AAHA’s Loenser hammered home the point that just because a post-H3N2 strain hasn’t appeared doesn’t mean veterinarians should relax.
“Influenza viruses can mutate,” she said. “Veterinary teams should remain vigilant for dogs and cats showing signs of influenza, including a high fever, ocular and/or nasal discharge, sneezing, coughing, anorexia and lethargy.”
More Ways to Defeat CIV
Zoetis Inc.’s “CIV Defense Handbook” offers a canine influenza outbreak management plan for veterinary hospitals. Some advice:
- Establish a chain of communication from the clinic to the community with questions like: How will the clinic communicate with their clients? What information should be conveyed to clients and the community?
- Educate staff and volunteers about CIV signs and risk factors by training staff to be alert to signs of respiratory infection, and providing written and oral instructions for all staff members and volunteers to ensure a consistent response if they notice signs of respiratory disease.
- Quarantine high-risk dogs for one week and isolate all dogs showing clinical signs of respiratory infection. Note that mildly affected dogs may transmit severe disease to others.
- Clean and disinfect contaminated clothing, hands, equipment and surfaces after exposure to dogs with respiratory disease, a history of boarding or recent transfer from high-risk areas.
- Ensure animals are appropriately vaccinated for CPiV, CAV-2, CDV, CIV and Bordetella bronchiseptica on intake.
- Clean and disinfect areas that have contact with large numbers of animals.
Zoetis Inc.’s “CIV Defense Handbook” has myriad tips for cleaning products and equipment.
- Clean with a detergent-based product first, then disinfect with bleach (5% NaClO diluted at 1:32 or 1/2 cup/gal), Virkon, Trifectant or Accel.
- Allow 10 minutes of contact time for disinfectants, followed by thorough drying.
- Surfaces contaminated with feces, urine, vomit, blood or nasal discharge must first be cleaned with detergent and rinsed before using disinfectant.
- More disinfectant is not better. Overly concentrated disinfectant solutions are damaging to skin, eyes and the respiratory tract, and can worsen disease due to tissue irritation.
- Dedicate separate cleaning supplies, rubber boots and disposable gowns to each area.
- After handling any dog, disinfect hands with 15 to 20 seconds of thorough handwashing with soap and water.
Originally published in the February 2017 issue of Veterinary Practice News. Did you enjoy this article? Then subscribe today!