Dog Health: When Viruses Jumps Species

By Sandra Murray


From the monthly column "Essential Elements" by Sandra Murray.  Originally printed in ShowSight – The Dog Show Magazine, June 2015 Issue. CLICK HERE TO SUBSCRIBE. 


Nothing adapts and mutates better than viruses. If a virus senses it has come under attack, it changes a few proteins or increases a chemical—whatever it takes to survive. If it can create a successful mutation that will allow it to jump over into a totally new species, so much the better. That is exactly what an avian virus from Asia did this year. It managed to do a shape-shifter mutation that can now invade domestic canines. This most recent species-jumping virus presents researchers and veterinarians with new challenges to diagnose dogs correctly and to begin the hard work of formulating a vaccination for it. An urgency to understand and treat this virus became critical in April of this year when cases of flu infections among the dogs in the Chicago area exploded with a vengeance. After Chicago veterinarians reported over a thousand cases resulting in the deaths of five dogs, the nation-wide community of canine practitioners and researchers raised the alarm.



Of special concern to dog show and performance event exhibitors, these groups needed to know immediately how to keep their dogs safe and well. A flurry of announcements and warnings were published in the hard press as well as in social media and online journals, blogs and magazines. Some of the advice came into question and rumors still fly across country, so let’s take a closer look at the histories of these flu viruses, how lethal they are and how to best avoid them.


So far, two known canine flu viruses have emerged in the 21st century. The first one (H3N8) has existed in horses for more than 40 years, but mutated to perform the dreaded species jump in 2004 when it was found in dogs for the first time. Racing Greyhounds in Florida in January of 2004 first showed symptoms of a flu virus not seen before in dogs. From 2004 to 2006, an upper respiratory virus attacked racing Greyhounds in 9 states and caused 7 deaths. Because these dogs were maintained in close quarters with their kennel mates and they travel across country to race meets in other states, they brought the virus with them to infect other dogs as well as the track facilities where they were housed. The dogs that died had pneumonia with extensive hemorrhaging in their lungs. Predictably, soon dogs in animal shelters, boarding kennels and veterinary clinics in Florida and New York in 2004 and 2005 showed symptoms of acute respiratory distress from the virus. By 2008 veterinarians had reported affected dogs in 25 states and the District of Columbia. However, the death rate remained low. Meanwhile, in the UK, kennels of working Foxhounds reported an outbreak of canine influenza among their packs that had been on hunts with horses. In Australia in 2007 during an epidemic of equine influenza, dogs kept near infected horses became ill with the newly mutated equine, now canine, influenza. All it took for the equine virus to mutate into a canine one was a change of just 5 different amino acids.


Of course, from the moment that researchers had confirmed that H3N8 was a new canine virus, work began to formulate a vaccine that would protect dogs. In 2009 such a vaccine received approval and there are now several H3N8 vaccines available.


The second virus and the one causing all the trouble in the Chicago area, has come to our shores via Asia. It began as a virus limited to birds, but it has mutated into quite a large family. Dubbed H3N2, this avian influenza virus had already mutated into a strain that jumped species into pigs and now is endemic in pigs in China. It was the source of the massive die off of pigs in that country last year and has now been detected in pigs in Thailand and Vietnam. Whether H3N2 migrated in its newly mutated form as a canine virus to our shores via pigs or birds is unclear, but it is here to stay. In Asia the pig form of H3N2 mutated into a human strain of virus which is now one of the main strains of seasonal flu that humans contract. However, the good news is that this new canine strain of H3N2 does NOT transfer to humans. The bad news is that household cats can and do contract H3N2. If you think that H3N2 sounds a bit like the mythical, evil hydra, you’d be right! Perhaps now you can better understand the frustration of researchers who play an endless game of “whack a mole”, finding a vaccine for one strain of the virus only to have another pop up to cause trouble.


In watching your dogs for symptoms of canine flu, two clinical syndromes may appear in those infected with the virus—
a mild form of the disease and a more severe form that is accompanied by pneumonia.


• Mild form—Dogs suffering with the mild form of canine influenza develop a soft, moist cough that persists for 10 to 30 days. They may also be lethargic and have a loss of appetite and a fever. Sneezing and discharge from the eyes and/or nose may also be observed. Some dogs have a dry cough similar to the traditional “kennel cough”. Dogs with the mild form of influenza may also have a thick nasal discharge, which is usually caused by a secondary bacterial infection.


• Severe form—Dogs with the severe form of canine influenza develop high fevers (104ºF to 106ºF) and have clinical signs of pneumonia, such as increased respiratory rates and effort. Pneumonia may be due to a secondary bacterial infection.


Fortunately, the mortality rate is low —less than 10%—but we hate to see our dogs sick at all. The H3N8 vaccines remain available, but no one knows as yet how effective they might be in preventing the H3N2 virus. Some veterinarians and researchers recommend giving your dogs the vaccine if they haven’t already received it in hopes that it might at least reduce the severity of the H3N2 influenza strain. No doubt researchers are currently working on creating a vaccine for the H3N2 canine flu.


For dog owners already concerned about the number of vaccines that we give our dogs, especially in light of the revised vaccination protocol recommended by Dr. Jean Dodds and adopted by some veterinary colleges, news of another vaccine makes them shudder. Autoimmune diseases do occur in dogs and many believe that the resulting allergies, joint disease, hypothyroidism and even some cancers are too high a cost to pay for over-vaccinating our dogs. Even conventional veterinarians will agree that vaccinations suppress a dog’s immune system, rendering them more vulnerable to illness for a full week. That could make giving the available H3N8 vaccine—which takes 2 doses given 2 to 4 weeks apart—problematic for a very young, geriatric or immune compromised dogs. Then there is the matter of money. The H3N8 vaccination costs around $100 with no guarantee that it will do any good against this new species-jumping H3N2 canine influenza.


Another aspect of the money game in vaccinations is something called “seeding”. Pharmaceutical companies make a great deal of money from vaccines.


Veterinary vaccine sales are a very profitable branch of their vaccine business, so it behooves them to have a strategy for good sales. Enter the practice of seeding: “To create loyalty and advocacy towards a brand [vaccine], seeding trials take advantage of opinion leadership [veterinarians] to enhance sales. In a seeding trial, the brand provides potential opinion leaders with the product for free, aiming to gain valuable pre-market feedback and also to build support among the testers, creating influential word-of-mouth advocates for the product. By involving the opinion leaders as testers, effectively inviting them to be an extension of the marketing department, companies can create a powerful sense of ownership among the clients, customers or consumers that count by engaging the testers in a research dialogue.” (Wikipedia) The words in brackets I’ve added to help you see how seeding works in the veterinary medicine realm where either a new drug or a vaccine is publicized overtly or subtlety by veterinarians who are financially connected to one of the big pharmaceutical companies. Sometimes, the same veterinarian who is recommending a particular drug or vaccine in a television or radio interview also has monetary ties to such a company. The practice certainly is not illegal, but it is unethical and muddies the conversation as to the true need for the drug or vaccination in question.


For those of us who show in conformation or compete in performance events, the emergence of a new virus is much more than an academic or marketing concern. We need to know if it is safe to go to these events where large numbers of dogs are confined in one area. In checking with dog friends in the Midwest, it appears that the entry totals remain what they have been and absences are well within the normal 10% range, so those in the fancy are still out there exhibiting and competing. What responsible competitors are probably already doing is not lingering in the exhibition building or grooming areas with their dogs. They show them and then take them out of any confined area where there are lots of dogs. They take their dogs to the far corners of the show site for those potty breaks and spend more time in the van or RV. Certainly, dog owners should avoid taking their dogs to dog parks, doggy day care or boarding facilities if canine influenza has been reported in their area.


There are also natural immune boosters to help strengthen your dogs’ immune systems to avoid contracting canine influenza: turmeric oregano and fresh garlic, as well as useful herbs and diffusing virus-fighting essential oils to support the immune system. A holistic vet will be able to guide you in choosing which herbs and oils will work best for your dogs.


Finally, it will be up to us to sort through all of the hard copy and digital media buzz, to speak with both conventional and holistic veterinarians and then to come to our own conclusion as to what will be best for our dogs. We are their advocates, defenders and care givers. The latest species-jumping virus will pass. But because we live in a global economy, another mutating virus will follow soon from some far flung part of the world. This is the new normal and we have to adjust to meet it so that we can best care for ourselves and our dogs. 


Until next time,



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