A cough, runny nose, fever, and lethargy. In dogs, these are classic signs of highly infectious upper respiratory problems that are lumped under the broad term “kennel cough.” The specific pathogen causing kennel cough may be viral, bacterial, or a combination of these. Because many different pathogens cause kennel cough, laboratory testing is required to pinpoint the cause.
A recent respiratory disease outbreak among Chicago area dogs led to the temporary closure of doggie daycares, kennels, and other dog-related businesses in order to keep the bug from spreading further. There are limited veterinary diagnostic laboratories that offer panels to test for the numerous agents that can cause canine respiratory illness. Although supportive care is the usual course of treatment when the cause is viral, it is important to perform rapid diagnostic testing in outbreak situations to quickly implement measures to prevent spread. In the Chicago outbreak, weeks passed before many cases were confirmed through molecular testing to be canine influenza virus.
The inconvenience of mailing out samples and the time spent waiting for test results are roadblocks in slowing the spread of this disease, and that delay is a problem that Dr. Elizabeth Driskell at the University of Illinois College of Veterinary Medicine is hoping to solve.
Dr. Driskell, a veterinary pathologist and faculty member in the Department of Pathobiology, is an expert on Influenza A virus. She is currently researching how canine influenza virus behaves in the dog host and looking for better methods of early, on-site detection of canine influenza virus. For her, the Chicago outbreak is an opportunity to gather samples for her research.“Acquiring clinical samples of the virus during an outbreak can help us figure out how the virus got there and identify any important changes in the virus that may render the virus more virulent or the vaccine less effective,” explains Dr. Driskell. She is distributing kits to veterinarians for taking swabs from infected dogs they see at their clinics.
As the name indicates, canine influenza is the dog version of flu and is related to the same group of influenza viruses that causes influenza in humans and other animals. There is no current indication that canine influenza virus would transmit to humans. Canine influenza first emerged in 2004, when the H3N8 influenza strain made the jump from infecting horses to infecting dogs, although studies have indicated the virus has been in the dog population since 1999. Despite worries that the virus would spread rapidly in dogs, sustained transmission of canine influenza virus has been only in a few places in the United States and is associated with group housing of dogs.
“Many dogs are naïve to this infection because it is a newer virus,” explains Dr. Driskell. “This leaves them with no protective immunity against it. When we do have outbreaks, such as in Chicagoland right now, they are fairly explosive because of this lack of protection.”
There is high morbidity, meaning the virus infects many dogs, and low mortality with canine influenza virus. Although not usually deadly, sometimes infection with canine influenza virus leads to pneumonia, typically associated with a secondary bacterial infection, which leads to more severe disease and possibly death.
“Transmission occurs via respiratory secretions from dog to dog and can also be transmitted by contaminated objects. This is why we often see cases linked to doggie day cares, animal shelters, and any other locations with a high dog concentration,” says Dr. Driskell.
“It is important for us to distinguish what pathogen is responsible for an outbreak of kennel cough. If it is canine influenza, we need to monitor it in order to prevent spread and to see if the virus is mutating. Even though it causes relatively low mortality right now, a mutation could lead to the virus causing more severe illness or becoming more contagious,” she says.
Dr. Driskell is currently working on research that focuses on host responses as a way to diagnose canine influenza.
“A local host innate immune response is basically the quick response that happens in the respiratory tract when there is a viral infection,” says Dr. Driskell. “The body secretes substances and increases various signaling molecules to fight infection. We can study these immune responses to see if there is a specific pattern that is unique to infection with viruses or even specifically canine influenza virus. Potentially we could swab the respiratory tract of a patient with kennel cough to detect these molecules for diagnosis instead of looking for the actual virus, which can be problematic.”
Dr. Driskell is using an explant tissue culture system model for the study. This involves using respiratory tissue and infecting it with virus to see how the tissue responds.
“The host responds to bacteria and individual viruses differently. If veterinarians can detect a viral infection earlier, they can make effective prevention and treatment choices sooner,” Dr. Driskell says. “With our prospective diagnostic platform, veterinarians could use an in-house testing device to determine this information right in their clinics when they first see the patient instead of sending a sample to a distant lab and waiting days for results.”
By Melissa Giese