Canine Influenza in Oregon

    Oregon's first case of the emerging canine influenza was confirmed on Friday, September 30, by the veterinary virology laboratory at Cornell University in New York. 

    The sample was submitted by Dr. Zoe Tokar of Powell Blvd. Veterinary Clinic and was from a four-year-old spayed female who was presented to the Portland practitioner with a severe cough and a fever of 103.5 Fahrenheit.  According to a notice sent to the OVMA office by Dr. Emilio DeBess, Oregon's Public Health Veterinarian, the samples (oral swab and serum) were collected and sent to Cornell for testing.  The serum titer was positive at 1:1024 and a PCR test was negative.

    An article on the dog flu that ran in The Oregonian indicated the State of Oregon does not have the ability to test for the disease and that officials are waiting for the results on 12 other blood samples that were drawn from dogs at the Multnomah County Animal Shelter.

    Dr. Edward Dubovi, director of the virology lab at Cornell, expects the lists of states with positive samples to grow, as the lab processes more tests.  Positive cases have already been seen in Florida, New York, New Jersey, Massachusetts and California, with Oregon just added to the expanding list.

    Below is additional information on the Canine Influenza, which was forwarded to the OVMA office by Dr. DeBess.

    Situation: University of Florida researchers report that outbreaks of canine influenza virus, which causes and acute respiratory infection, have been identified in dogs in shelters, humane societies, boarding facilities and veterinary clinics in Florida, predominantly in Broward, Dade, Palm Beach and Duval counties.

    This highly contagious virus is a newly emerging respiratory pathogen in dogs and causes a clinical syndrome that mimics "kennel cough."  Canine influenza virus infections are frequently mistaken for infectious due to the Bordetella bronchiseptical Para influenza virus complex.

    Clinical signs:  Because this is a newly emerging pathogen, all dogs, regardless of breed or age, are susceptible to infection and have no naturally acquired or vaccine-induced immunity.  Virtually 100 percent of exposed dogs become infected.  Nearly 80 percent have clinical signs.  There are two general clinical syndromes-the milder syndrome and a more severe pneumonia syndrome.  The milder disease syndrome occurs in most dogs.

    In the milder disease, the most common clinical sign is a cough that persists for 10-21 days despite therapy with antibiotics and cough suppressants. Most dogs have a soft, moist cough,  while others have a dry cough similar to that induces by the Bordetella bronchiseptical/Para influenza virus infection.  Many dogs have purulent nasal discharge and a low-grade fever.  The nasal discharge likely represents a secondary bacterial infection that quickly resolves with treatment with a broad-spectrum, bacterial antibiotic.

    Some dogs develop a more severe disease with clinical signs of pneumonia, such as a high fever (104 to 106 degrees Fahrenheit) and increased respiratory rate and effort.  Thoracic radiographs may show consolidation of lung lobes.  Dogs with pneumonia often have a secondary bacterial infection and have responded best to a combination of broad-spectrum, bactericidal antibiotics and maintenance of hydration with intravenous fluid therapy.

    Fatality rate:  Fatal cases of pneumonia have been documented, but the fatality rate so far is low, at 1 percent to 5 percent.

    Incubation/shedding period:  The incubation period is two to five days after exposure before clinical signs appear.  Infected dogs may shed the virus for 7 to 10 days from the initial day of clinical signs.  Nearly 20% of infected dogs will not display clinical signs and become the silent shedders and spreaders of the infection.

    Diagnosis:  There is no rapid, real-time test for diagnosis of dogs with an acute influenza virus infection.  Current diagnostic tests rely on detection of antibodies to canine influenza virus, which are detected as early as 7 days after onset of clinical signs.  Paired acute and convalescent serum samples are necessary for diagnosis of recent infection.  The convalescent sample is collected at least 2 weeks after the acute sample.  There are many situations in which collection of an acute sample is not feasible.  In this case, testing of a convalescent sample will indicate whether the dog was infected at some time in the past.  Serology tests not only indicate if a dog was infected, but also serve to alert veterinarians that the virus is present in their community so they can take precautions with dogs presenting for "kennel cough."

    In addition to serology, the lungs and distal trachea from dogs that died of pneumonia can be tested for influenza virus by PCR analysis and virus culture.

    Prevention:  There in no vaccine for canine influenza virus at this time.  This virus is spread by  aerosolized respiratory secretions, contaminated inanimate objects and even by people moving back and forth between infected and uninfected dogs.  This is an enveloped virus that is most likely killed by routine disinfectants, such as quaternary ammoniums and 10% bleach.  Because the virus is highly contagious and all dogs are susceptible to infection, veterinary  and, boarding facilities, shelters and pet stores should use isolations protocols for dogs that have a "kennel cough."

    What veterinarians can do:  Veterinarians can submit serum samples for canine influenza antibody titers.  Paired acute and convalescent samples are preferable for confirmation of infection, while single samples collected after seven day of clinical disease are also useful.  In addition to determining infection, these samples will contribute toward virus surveillance in Florida and other states.

    Veterinarians may also submit fresh (no formalin or freezing) lung and tracheal tissues from dogs that die from pneumonia.  Canine influenza virus culture and PCR  analysis will be preformed on these tissues.  Virus recovered from these samples will greatly contribute toward development of vaccines and diagnostic tests.

    Initially, Dr. Cynda Crawford was conduction ongoing tests for canine influenza.  However, she  presently is referring veterinarians to submit samples for testing to  Dr. Dubovi.

    According to Dr. Crawford, Dr. Dubovi is coordinating testing efforts with her and is the central point for canine flu.  She said he is better equipped with trained personnel, expertise, supplies, and can handle a higher volume than can her research lab at the University of Florida's College of Veterinary medicine.

    The Web site for Cornell  University's veterinary laboratory is www.diaglab.vet.cornell.edu/news.asp.  The site contains information regarding what samples to submit, how to submit, and pertinent charges.  There is no limit on how many samples to send, except for associated costs.  You and also contact the laboratory switchboard by calling (607)253-3900.

Copied from the OVMA Sept../Oct. 2005 issue