Canine influenza: The dog flu

The H3N8 equine influenza virus has been recognized in horses for more than 40 years. About five years ago, the H3N8 influenza or “flu” appeared to have jumped from horses to dogs. The virus had mutated into a form that was highly infective for dogs. At first veterinarians thought the H3N8 canine flu would be quite lethal. Fortunately, like the human flu virus, it kills very few healthy individuals. It has been verified in 30 states to date.

The discoverer of the disease, Dr. Cynda Crawford from the University of Florida, estimates it kills between 5 and 8 percent of dogs that contract it. That’s nothing to sneeze at. The 1918 Spanish flu had a mortality rate of only 2 percent. A vaccine was recently approved in the U.S. and is now available from veterinarians. Vaccination against canine flu should be considered for any at-risk breed, dogs with pre-existing conditions, those that travel or show or have extensive contact with other dogs.

1. What are the signs of canine influenza? How should pet owners know when to suspect C.I.V rather than kennel cough? How should they know when to see the vet?

The symptoms of canine influenza are similar to the human flu: cough, runny nose and fever. CIV is virtually identical to other respiratory infections such as kennel cough. In fact, many cases of CIV may be mistaken as kennel cough or other infections in the canine infectious respiratory disease (CIRD) complex because of these similarities. Because of the difficulty in distinguishing CIV from CIRD, any dog with these clinical signs should be seen by a veterinarian. Older dogs or dogs with existing heart and respiratory conditions are at particular risk. Dogs with short, flat faces such as Pugs, Boxers, Shih Tzus, Pekingese and Boston Terriers are also in potential jeopardy.

2. If an owner suspects their pet has influenza, what can they do to help care for it after the trip to the vet? How severe is the infection in the majority of patients? How many dogs will develop complications and what can owners do to prevent that?

Virtually 100% of dogs exposed to H3N8 will become infected. For this reason, it is important that owners of dogs with CIV keep them away from any unvaccinated dogs. This includes trips to the groomers or dog parks, contact with other dogs during walks and kennels. Clothing, equipment, floors and hands should be cleaned after contact with any dog with signs of respiratory illness.

About 80% of infected dogs will develop respiratory signs while the remaining 20% will remain healthy and continue to spread the infection. Most infected dogs will develop clinical signs within two days of exposure to H3N8. Current research indicates an infected dog stops shedding the virus approximately seven to ten days after the start of clinical signs. Just like the human flu virus, CIV is most infectious before a dog shows signs of illness. Because many dog owners won’t know when their dog contracted CIV, we advise quarantining infected dogs for two weeks after diagnosis. CIV is fatal in less than 8% of cases.

A small percentage of dogs, especially those that are older, have pre-existing conditions or short-flat faces will develop pneumonia. These are the dogs at risk for serious complications, including death.

3. What tests will a veterinarian run to determine whether a dog has influenza? What factors would influence a vet’s decision to test?

If a dog is seen by a vet within a day or two of clinical signs, a nasal swab test can be submitted to a veterinary diagnostic lab. If a dog owner brings in a dog that has been sick for several days or more, the only way to confirm CIV is by performing two blood tests two to three weeks apart. Any dog suspected to have CIV should be tested to help us track the spread of this highly infectious disease. If there are confirmed cases in your area, vaccination becomes more important.

4. What are the benefits and risks of the C.I.V vaccine? Who should get it? Are dogs in certain parts of the country more likely to be good candidates?

The decision to use any vaccine is based on each individual’s risk. Indoor dogs with little exposure to other dogs are at less risk than show dogs that travel or dogs frequently kenneled. Dogs that live in areas where outbreaks are occurring should also consider vaccinating against H3N8. Cases have been identified in 30 states and the District of Columbia. Florida, Pennsylvania, New York, New Jersey, Colorado, California, Delaware have had confirmed outbreaks. Older dogs with respiratory or heart disease and breeds with short, flat faces such as Pugs and Boston terriers should also consider vaccination.

It is important to note that the CIV vaccine can’t completely prevent disease. The benefit of the vaccine is that it reduces the clinical signs to a very mild form and decreases the risk of shedding the virus. This is especially important in at-risk dogs and to help reduce the spread of outbreaks.

5. How is CIV different from human seasonal flu and the H1N1 virus? Are dogs at risk for an epidemic of canine flu?

In many ways, H1N1 in people and H3N8 in dogs are similar. Both are viruses that mutated form one species to another and are new infections that neither humans nor dogs have been exposed to before. Both cause fever, runny nose and coughing that lasts for a week or two and makes you feel crummy. Because the immune systems have no defense against these new viruses, quarantine and vaccination are our best strategies to prevent widespread infection. We haven’t done well containing H1N1; let’s hope we do better with CIV.

CIV poses no threat to humans and is being closely monitored by the CDC and its partners. If your baby does get CIV, you can feel comfortable giving it plenty of TLC. After all, sometimes the best medicine is a healthy dose of love.

My best advice is don’t panic; the chances of your dog contracting CIV are slim. If your dog is around a lot of other dogs, has heart or breathing problems or you live in an outbreak area, have your dog vaccinated. Otherwise, keep in contact with your vet, groomer, or kennel to find out if “something’s going around” and take appropriate measures such as keeping your dog home or vaccinating. This is especially important around the holidays when many people kennel or travel with their dogs.

The best way to protect your dog from CIV is through avoidance or vaccination.