What to know about a mysterious dog respiratory illness

The mysterious respiratory illness that may have sickened scores of dogs across the country could be caused by a new type of bacterial infection that may be very good at evading the canine immune system, researchers say. Some dogs have died from the illness that starts with causes a cough that can last for weeks, runny eyes and sneezing.

In a development that might help shed light on the illness, which has affected a range of dog breeds, researchers at the University of New Hampshire’s Veterinary Diagnosis Laboratory and the Hubbard Center for Genome Studies told NBC News they have identified a pathogen that might be what’s making pets sick.

Through a genetic sequencing of samples from an initial group of 30 dogs from New Hampshire who were infected last year and then an additional 40 from Rhode Island and Massachusetts who got sick this year, the researchers say they have discovered a previously unknown germ.

The pathogen is “a funky bacterium,”  said Dr. David Needle, pathology section chief at the College of Life Sciences and Agriculture at the University of New Hampshire. “It’s smaller than a normal bacterium in its size and in the size of its genome. Long story short, it’s a weird bacterium that can be tough to find and sequence.”

The germ “is new as a potential cause of disease, but it is likely to be— or to have evolved from — a component of the dog microbiome,” he said. Dogs as well as humans have multiple types of harmless bacteria and other microorganisms living both inside and outside the body. In the gut, they are thought to aid in digestion.

The bacterium was discovered after a painstaking search.

“After initial sequencing showed there were no known viral, bacterial or fungal pathogens, time consuming and dogged work by graduate student Lawrence Gordon showed that 21 of the initial 30 samples from New Hampshire had some genetic material from one atypical bacterial species,” Needle said.

The UNH team is sharing its results prior to publishing a research article, hoping they will give veterinarians some information as they deal with other respiratory syndrome outbreaks, he said.

Scientists aren’t even sure yet whether the same bug is making dogs sick across the nation. Many researchers have wondered whether it was a bacterial or a viral pathogen. One thing veterinarians do know is that the germ is something they don’t recognize.

New Hampshire is one of at least 10 states that have reported cases of the respiratory infection in dogs.

The Oregon Agriculture Department has received more than 200 case reports from veterinarians around the state since the beginning of August, spokesperson Andrea Cantu-Schomus said in an email. A very small percentage of the dogs have died, Cantu-Schomus said.

Other states with reported cases include:

• Colorado
• California
• Indiana
• Illinois
• Washington
• Idaho
• Georgia
• Florida

Because there is no test yet for the illness and because many of the symptoms are similar to other respiratory infections, such as canine influenza and Bordetella (kennel cough), it’s unknown exactly how many dogs have been affected. With hundreds of cases identified by symptoms only reported in Oregon alone, it’s likely there are thousands.

Normally, to determine what antibiotics might work best against a particular type of bacteria, labs grow the bugs in a petri dish and then try to kill them with various medications. Needle and his colleagues have not been able to grow the new bacteria in the lab. Nevertheless, its structure offers some clues about which medications might be the best choice to fight it, he said. The antibiotic doxycycline may be effective, he suggested.

If it turns out that the New Hampshire researchers have found the right microbe, that may explain why some dogs are getting very sick, said Dr. Karl Jandrey, a professor of clinical small animal emergency and critical care at the University of California, Davis, School of Veterinary Medicine.

Smaller pathogens are likely to have an easier time making it past a dog’s defenses in the upper respiratory tract and getting down into the lungs, he said. “If it goes into the lungs, there’s a risk of pneumonia,” he added.

According to Oregon’s Cantu-Schomus, the dogs’ illnesses largely develop in three ways:

• As an inflammation of the tubes that connect the throat to the lungs that is minimally or not responsive to antibiotics.
• As chronic pneumonia that is minimally or not responsive to antibiotics.
• As acute pneumonia that rapidly becomes severe and often leads to severe illness or possibly death in as little as 24 to 36 hours. 

If a dog has a cough that won’t quit and other respiratory symptoms, it’s recommended that the owner contact a veterinarian.

While the respiratory symptoms seem to be like a viral illness, testing has been negative for a virus, Cantu-Schomus said.

It’s very unlikely that the cause will turn out to be viral, said Colin Parrish, a professor of virology at the College of Veterinary Medicine at Cornell University. “With the sequencing methods people use to look for unknown viruses, its signature would have been clear in a few days,” he added.

So it’s possible that the New Hampshire scientists could have  hit upon the right pathogen, although their results need to be confirmed by more research, he said.

Even though a record number of Americans are expected to travel during the holiday season, experts recommend that dog owners keep their pets out of kennels and other areas, such as dog parks, where infection might be more likely because of crowded conditions and close contact.

“When you congregate a bunch of animals together, there’s a larger likelihood of getting an infectious disease from other dogs,” said Dr. Kurt Williams, director of the Oregon Veterinary Diagnostic Lab at the Carlson College of Veterinary Medicine at Oregon State University.

Still, he said, there are some facilities where you are less likely to have a problem because of how they are designed.

“I’ve been telling people to work closely with their vet,” Williams said. “And to make sure their dog has all the vaccines available, in particular those for respiratory diseases we are familiar with.”

Another option is for owners to hire a house sitter, Needle said. “Or hire a dog walker,” he added. “It might not be perfect, but it’s better than nothing. Also, you might want to consider having Thanksgiving at home.”

Ultimately, your dog might be happier at home with a house sitter or a dog walker stopping by multiple times during the day than going to a kennel, Jandrey said.

“It’s best to leave them in their own environment,” he added.

Linda Carroll

Linda Carroll is a regular health contributor to NBC News. She is coauthor of “The Concussion Crisis: Anatomy of a Silent Epidemic” and “Out of the Clouds: The Unlikely Horseman and the Unwanted Colt Who Conquered the Sport of Kings.”