Dear Pet Docs: I have been reading about the dog flu epidemic in the Midwest. Should I be worried here in South Carolina? How do I protect my dog?
A: Fortunately, we do not see many viral infections in dogs as our vaccines are so affective at providing protection. Our emergency service will see several cases of parvo annually in young or unvaccinated dogs. We see the viral infection distemper only every couple of years now. Prior to the availability of vaccines 30 years ago, hundreds of dogs would die yearly from these diseases. The frustrating problem with viruses though is new ones are always developing.
Canine Influenza (CIV) or dog flu is one of these. It was initially caused by a strain of equine influenza that jumped from horses to dogs and is now considered dog specific. The first reported cases were in racing greyhounds in Florida in 2004 and were called H3N8. The H and N refer to proteins on the outer surface of the virus that help them enter the dog’s cells. The numbers refer to how many of these proteins there are.
The newest strain, H3N2, was first identified in China and Korea in 2006 and no one knows how it got into the United States. Since it is a new strain that dogs in the U.S. have never been exposed to, they do not have any immunity against it.
Most infected dogs will develop a dry or moist cough that lasts two to three weeks. Clinical signs vary from dog to dog and may include a cough, sneezing, runny nose, eye discharge, poor appetite and lethargy. About 20 percent of dogs develop life-threatening issues such as pneumonia, labored breathing and fever. About 5 percent of infected dogs will die.
Dogs are infected with the flu virus the same way we are, by exposure to respiratory secretions in the air or on surfaces and people. It can live up to 48 hours on counters and floors, 24 hours on our clothing and 12 hours on our hands. If infected, symptoms usually develop within the next 48 to 96 hours. About 25 percent of dogs will be infected but have no symptoms yet still shed the virus.
Since dogs in the U.S. has been exposed, they have no immunity and are susceptible to infection. Dogs shed the most virus particles during the period between infection and clinical signs. This means they are the most contagious before we even realize they are infected. They remain contagious for about 10 days once symptoms start.
We will be suspicious of CIV infection based on the symptoms a dog is having and the history of potential exposure. Early infections, usually within four days of symptoms, can be diagnosed by swabbing the nose or throat and performing a polymerase chain reaction test (PCR) to look for the virus’ genetic material.
The diagnosis also can be confirmed by obtaining a blood sample and determining if the dog is making antibodies to fight the infection. It takes about one week for these antibodies to be produced, so often we obtain an early infection sample and a 1-2 week sample. Active infection is diagnosed if the later sample is at least four times the early sample.
So initially, the diagnosis is made based on our physical examination and history the parents provide. It is later confirmed with the blood tests.
Unfortunately, there is no specific treatment for CIV infection. Basically, we support them while their bodies fight off the infection. We make sure they stay hydrated, provide nutrition when not eating and treat secondary bacterial infections if present. In dogs with pneumonia, oxygen therapy may be needed to keep them alive. Fortunately, most dogs recover completely in two to three weeks.
There are several ways to prevent your dog from becoming infected. If dogs in our area are reported to be infected with canine influenza, temporarily avoid visits to dog parks, shows, pet festival, groomers or anywhere your dog may be exposed. The virus can be easily killed by common disinfectants.
If something is contaminated, clean it with a 10 percent bleach solution. Washing hands and clothing will prevent transmission as well.
We can vaccinate for the H3N8 strain, but while the vaccine does not prevent disease, it does decrease symptoms, duration and shedding. We do not know if the vaccine protects against the H3N2 strain, but experts believe it will provide some protection.
Here in South Carolina, I (Perry Jameson) would not rush to get my dog vaccinated. Vaccinate only if your dog is going to be in a high-risk area. This type of decision is where having a good relationship with your pet’s family veterinarian is important.
As for now, this is not a problem in our area and, hopefully, it will not be. The best prevention is the same for dogs as people: avoid exposure and practice good hygiene.
Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to email@example.com.