No one wants to hear “kennel cough.” It can strike fear in the heart of any boarding kennel operator, shelter director, veterinary practice manager or breeder. But when most people hear those two words, if they know it’s actually canine infectious respiratory disease, they think “bordetella.”
Well, it could be. But then again, maybe not.
Such is the state of viruses and bacteria in both the canine and human world that any one of a number of either can cause the disease, which is, as its name suggests, infectious, and depending on the virus or bacterium, highly so.
On top of that, says Richard Ford, D.V.M., DACVIM, DACVPM, more than one virus or bacterium often contributes to the disease.While veterinarians, specialists and researchers are aware of the “recognized agents” of CIRD, “we always acknowledge that there are other agents” that may be involved, says Ford, a former professor of internal medicine at North Carolina State University, who researched and wrote about the disease for many years.
Among the agents known to be at the center of CIRD are Bordetella bronchiseptica, parainfluenza virus, canine influenza virus, canine adenovirus-2, canine respiratory coronavirus and Streptococcus zooepidemicus.Of those, vaccinations are available for bordetella, parainfluenza, influenza and adenovirus-2. The coronavirus vaccine, not currently recommended by the American Animal Hospital Association guidelines, is for a virus of the digestive tract, rather than the respiratory system. For now, our dogs are on their own with coronavirus and strepto zoo, as Streptococcus zooepidemicus is known.
Also involved may be some mycoplasma species, Ford says. These very tiny bacteria are “really probably more common than we realize, but understudied. We don’t know what the significance of those are.”
In addition, “We will continue to see emerging bacteria and viruses that will play a role,” Ford says.
“This is not a simple disease,” he explains. “It’s a complex infection. The real challenge is to prevent the infection.” The two ways to do this are to prevent your dogs’ exposure to other dogs, which is “not always easy to do,” he says, and to take advantage of available vaccines. “The bottom line is it is important to prevent it, through the use of vaccines, when a vaccine is available and when the risk of exposure exists.” Ford places emphasis on the “and” in his bottom line.
If you take your dogs to a daycare facility or anywhere multiple dogs are exposed to one another, canine infectious respiratory disease is a concern. It’s a quickly multiplied concern for people whose business it is to care for, exercise and house groups of dogs. “These viruses are very readily spread through the air,” he says. “There are outbreaks that shutdown veterinary practices. The risk is significant.”
A Respiratory System Primer
Of course, we all know that we need our respiratory systems to breathe, as do our dogs. They’re the source of our oxygen and also remove carbon dioxide from our bodies.
Just in case you’re not familiar with how it works, here’s what the Merck Veterinary Manual says about it: “Gas transfer occurs in the alveoli of the lungs, where the air-blood barrier is a thin, permeable membrane. Failure or major dysfunction of gas transfer due to disease processes that compromise this membrane or its air or blood supply have serious effects.”
In addition to that major function, the respiratory system maintains acid-base balance, acts as a blood reservoir, filters and likely destroys emboli, or blood clots, metabolizes substances such as serotonin, corticosteroids and others, and activates other substances, such angiotensin, a hormone, according to Merck. “The respiratory system also protects its own delicate airways by warming and humidifying inhaled air and by filtering out particulate material. The upper airways also provide for the sense of smell and play a role in temperature regulation in panting animals.”
So, when you’ve got multiple agents infiltrating the system, intent on doing damage, it’s no small problem.
Bugs Among Us
The trouble with bordetella and strep zoo – short forStreptococcuszooepidemicus – is that “a lot dogs” have these bacteria, but “show no clinical disease,” Ford says. They go about their daily lives perfectly normally “unless you add influenza to it.” Strep zoo, in particular, is a “huge co-factor” in canine infectious respiratory disease. On the other hand, a dog can have canine influenza without showing any signs whatsoever, Ford says. But add in bordetella, and “you’re going to see disease.”
However it comes about, “these dogs become clinically ill really quickly. It is a co-infection and co-morbidity issue,” meaning multiple conditions contribute to the sickness and to death, if it comes to that.Fortunately, despite the attention paid to canine flu in recent years, it’s fairly rare, Ford says.
Based on the dog’s clinical signs, including the infamous cough, “it’s very difficult to judge the causative organism,” Ford says, although the severity of the cough “may give some clues.” Knowing where the dog has been recently and how long before the cough started help the diagnostician determine whether the cough is due to canine infectious respiratory disease or another condition. “These are relatively acute infections,” Ford says, that emerge “within a matter of days after exposure.”
“What’s lacking in scientific knowledge is what combinations cause the disease,” he adds.
Beyond the Cough
When a dog does get sick beyond the classic cough, though, there’s nothing a veterinarian or specialist can do for the influenza, other than provide support, such as fluids. “We have vaccines to prevent them, but no anti-viral to treat them. It’s a matter of managing the respiratory infection and the population at risk,” Ford says. Antibiotics, however, can be administered to get the bacteria under control. And other clinical signs can be treated as they develop.
“It’s really symptomatic treatment. If they’re really severe, they’ll be hospitalized and put on antibiotics and fluids.”
Because the disease is a complex, multiple agents acting alone or in combination with each other can lead to death, Ford says. However, “The true death is from pneumonia and other problems,” not CIRD. Fortunately, if a dog has access to treatment, the “risk of death is extremely low,” he says.
Dogs housed in shelters are at greatest risk of developing severe respiratory disease, which occasionally leads to death. Because shelter-housed dogs may not have access to regular veterinary care, euthanasia may contribute to higher death rates among dogs with CIRD in shelters.
Stopping the Spread
Organisms that contribute to canine infectious respiratory disease are “shed” from the respiratory tract of infected dogs, Ford explains. Depending on the vaccine used, it appears that even if a dog has been vaccinated, for example for bordetella, it can shed the organism. “We’re really concerned about that,” Ford says. “Our recommendation for co-housed dogs is that the vaccine administered should be an intranasal bordetella with parainfluenza. That’s going to provide the broadest protection. Intranasal vaccines tend to prevent shedding from the respiratory tract.”
While these bacteria and viruses are spread through direct contact or in the air over short distances, they don’t last long. At the most, Ford says, they could be on a surface for a few days. “They lose their ability to infect very quickly.”
However, people who groom, feed or care for dogs that are shedding organisms can spread it. This is especially true, Ford says, if the kennel of a sick dog is cleaned first, followed by the kennels of the healthy dogs. So, a protocol for handling anything that comes into contact with a canine infectious respiratory disease-affected dog should be carefully drafted and executed.
For the best chance of prevention in dogs with exposure risk, Ford says vaccination against bordetella and paraninfluenza are most important. Next is canine influenza. “If you’ve done those three, you’ve done a pretty good job of protecting against the major players,” he says.