Health Matters WCA Health Committee

Canine Virus (CIV) by Sheila J. Cook Msc

As early as the 1920s influenza was Virus is one of those fortunately rare shown to be caused by a virus. There events where an entire viral genome are however, three genetically very in this case, that of the H3N8 equine distinct types of influenza viruses: virus, was transmitted to dogs where : This is by far it adapted finally becoming canine- the most pathogenic type and is specific. responsible for pandemics such as the outbreak in 1918, Asian In in 2004, 22 sick racing flu in 1957, in 1968 and greyhounds were discovered; 14 had the Swine flu in 2009 that was caused a mild respiratory , moderate by the mysterious re-emergence of fever and coughing, while 8 had more a 1918-like virus. Influenza A viruses severe disease (bronchiopneumonia, infect several species including pleuritis, high fever) that ultimately birds, pigs, horses, humans and proved fatal. Upon necropsy, a now unfortunately dogs. There are H3N8 virus closely related to the many serotypes of the virus that are current viruses was classified based on antibody reactivity isolated from the respiratory tracts to two proteins present on the surface of these dogs. Further, similar cases of each virus particle – hemagglutinin of respiratory disease were reported (H) and neuraminidase (N). To date in racing dogs in 6 more states in 16 different H and 9 N molecules have 2004 increasing to 11 states in 2005. been identified. Interestingly, all H Serological epidemiology studies and N serotypes are found in wild showed that in addition to circulating aquatic birds which are therefore in racing greyhounds the H3N8 virus believed to be the natural host for had been transmitted into the general influenza A and act as reservoirs for pet population and by 2008, canine the transmission to other species. influenza was reported in 25 states. However, transmission from an intestinal virus of birds growing at Molecular analysis of the influenza 42oC to an upper respiratory tract isolated from dogs showed 96% infection of mammals where the homology with the 2002 and 2003 temperature is approximately 33oC equine influenza isolates, suggesting requires the virus to undergo many interspecies transmission from horse complex, incompletely genetic to dog. Although similar horse/dog changes. interspecies transmission has been documented in both the United mainly infects Kingdom and Australia, canine humans; although it has been influenza has so far become endemic documented in seals and ferrets. only in the US. In addition to H3N8 infects humans, dogs, other influenza serotypes have been and pigs, but is much less common. discovered in dogs. An H3N2 virus was isolated from dogs The emergence of Canine Influenza in South Korea with the potential

PAGE 10 * THE WEIMARANER MAGAZINE * OCTOBER 2011 to spread from dog to dog, and in viruses are constantly changing and Thailand, the highly pathogenic avian have a tremendous ability to alter influenza virus (H5N1) was reported their genome and with it the ability to in a dog that had ingested an infected infect different species. duck carcass. Although about 25% of the local dogs tested had antibodies to Clinical Signs of Canine Influenza: H5N1, spread from dog to dog was not Cough, runny nose and fever, with a observed in this case. small proportion of dogs developing severe disease, with . The How the equine H3N8 virus was is usually two to transmitted to dogs is unclear four days from exposure to onset of although popular theories include clinical signs. The highest amounts of close contact with infected horses, or viral shedding occur during this time; the ingestion of infected horse meat. therefore, dogs are most contagious Similarly, feeding on contaminated during this 2-4 day incubation period poultry products or aerosol when they are not exhibiting signs transmission from infected poultry of illness. Virus shedding decreases has been suggested for transmission dramatically during the first 4 days of the H3N2 virus in Korea. Both the of illness but may continue up to 7 strains of Influenza found is dogs are days in most dogs and up to 10 days in antigenically distinct from those found some dogs. The virus replicates in the in humans and unlike human influenza, mucosal lining of the respiratory tract the canine form is not “seasonal” and due to inflammatory responses, can result in rinhinitis, tracheitits, As dogs and horses live in close bronchitis and . It is association with humans and thought that approximately 80% in the case of dogs, share our of exposed dogs show clinical beds (especially in the case of signs of disease, while 20% remain Weimaraners) there is a concern that asymptomatic, though can still spread dogs (and horses) may provide a new the virus. source of a novel Influenza A virus transmission to humans. Could the Diagnosis: dog act as a “mixing vessel” like the There are two different tests to pig? One question you may ask is “Are determine whether your dog has dogs susceptible to human influenza influenza which can be performed infections – can I give my dog ‘my’ by your veterinarian. The first looks flu?” There is a recent report that the for the presence of virus in nasal recent novel H1N1 virus (2009 swine secretions taken at the onset of flu) has been observed in pet dogs in disease and the second looks for an China and the USA, following close increase of antibody to the virus. An contact with infected humans, but no initial serum sample is taken, followed reports of dogs transmitting the H1N1 two to three weeks later by a second virus to other dogs or humans. The sample. If there is an increase in transmission of flu viruses between antibody level that indicates your dog different species is based on viral has been exposed to influenza, either receptors, mainly found in the upper by infection or vaccination. The respiratory tract, that allow the virus timing of nasal swabs is critical and if to invade. If a species does not have taken once clinical signs are evident the right receptors, the virus cannot may produce a false negative as viral infect. But of course, influenza shedding will have ceased.

OCTOBER 2011 * THE WEIMARANER MAGAZINE * PAGE 11 Spread of Canine Influenza: In 1992, Lederberg et al., 1992 As with human influenza, canine published a report in the National influenza can be spread by direct Institutes of on Emerging Infections. contact with respiratory secretions, In it he concluded that ‘pathogenic via aerosol, people moving between microbes can be resilient, dangerous infected and uninfected dogs, or foes. Although it is not possible to contaminated objects. As with any predict their individual emergence in contagious disease, owners should use time and place, we can be confident common sense and quarantine their that new microbial will animals. emerge’. The emergence of Canine Influenza certainly holds that to be Treatment of Canine Influenza: true. Mainly supportive care, fluids. If a secondary bacterial infection occurs For more information: then broad spectrum antibiotics are http://www.cdc.gov/flu/canine/ administered. http://www.avma.org/public_health/ influenza/canine_bgnd.asp Control &Vaccines: http://www.cfsph.iastate.edu/ Influenza viruses, including canine Factsheets/pdfs/canine_influenza.pdf influenza viruses, are readily killed by commonly used disinfectants. Sheila Cook (MSc) is a Scientist II at In general, influenza viruses the University of Kentucky, Gluck are susceptible to a variety of Equine Research Center involved in disinfectants including 1% sodium research in Equine Infectious Anemia. hypochlorite, quaternary ammonium. Sheila has owed Weimaraners since Veterinary Influenza vaccines are 1987 and currently has, Sadie (15yrs) not the most effective drugs on the now retired who was her first agility market. For example, in the equine dog and first rescue to earn a MACH H3N8 influenza, as a result of genetic and Arran (6yrs) and Strider (almost variation, worldwide outbreaks have 3yr) who both achieved their MACH resulted despite regular vaccination. titles this year. In addition to agility, In 2009 an inactivated vaccine for Sheila also trains her dogs in both H3N8 canine influenza was given a field and obedience and is a member conditional license in the U.S. To of the WCA Health Committee. date, no significant variation in the H3N8 subtype (antigenic drift) has been observed with canine influenza References: but this should be closely monitored Equine and Canine Influenza: a review if vaccine efficacy is to be insured. of current events. E. Paul, J, Gibbs Canine can be and Tara Anderson. (2010) Animal termed a “lifestyle vaccine”. If you Health Research Reviews 11 (1); 43-51 think your dogs are at risk or in an Influenza virus infections in dogs area where there have been reports and cats. Timm C. Harder, Thomas of canine influenza virus outbreak, W. Vahlenkamp (2010). Veterinary then talk to your veterinarian Immunology and Immunopathology. about whether you should consider 134; 54-60 vaccinating you dog.

PAGE 12 * THE WEIMARANER MAGAZINE * OCTOBER 2011