Mystery Illness Killing Dogs in at Least 10 U.S. States

mystery illness killing dogs

Jessica McBride A mystery illness has been killing dogs. (the pictured dog does not have the ailment).

A mystery illness has been killing dogs or giving them infectious coughs and pneumonia in at least 10 states in fall 2023.

The Today Show reported that the mysterious dog illness has been reported in Oregon, Colorado, New Hampshire, California, Indiana, Illinois, Washington, Idaho, Georgia, and Florida.

According to, which is a Florida television station, “it starts with a cough and then can morph into pneumonia.” In Seminole County, Florida, eight dogs have been quarantined due to a respiratory illness that may be “kennel cough” or the mysterious illness, reported, adding, “It has the potential to kill and does not test like common dog viruses.”

The Oregon Department of Agriculture issued a warning about the disease on November 9, 2023, calling it an “atypical canine infectious respiratory disease” or CIRDC. ABC7 New York reported that the mystery dog illness was first reported in Oregon.

“On August 2023, the Oregon Department of Agriculture (ODA) began receiving reports of an atypical canine infectious respiratory disease (CIRDC) circulating in the Portland metro and Willamette Valley areas. ODA received over 100 reports of illness meeting the criteria from veterinarians,” the Oregon news release said.

Dr. Amanda Cavanagh, head of urgent care services at a veterinary teaching hospital in Colorado, told that she “started seeing cases of dogs with coughs lasting several weeks or even months, and the trend has continued into the fall.” She said that’s not uncommon, but this time the spike did not decrease as fall temperatures drop.

Here’s what you need to know

Oregon Officials Say They Are Working Hard to Figure Out What Causes the Illness in Dogs

Oregon heat map

State of OregonOregon heat map of the mystery illness killing dogs cases.

Oregon officials wrote that they are working to find the “causative agent behind these cases.”

“Based on the epidemiology of the cases reported to date, ODA says the cases appear to share a viral etiology, but common respiratory diagnostic testing has been largely negative. A handful of cases do test positive for M. cynos, but that is not believed to be the underlying causative agent,” they wrote.

The cases fall into these three categories, Oregon’s news release says:

Chronic mild-moderate tracheobronchitis with a prolonged duration (6-8 weeks or longer) that is minimally or not responsive to antibiotics.
Chronic pneumonia that is minimally or not responsive to antibiotics.
Acute pneumonia that rapidly becomes severe and often leads to poor outcomes in as little as 24-36 hours.

“We suggest caution rather than worry. Periodic outbreaks of Canine Infectious Respiratory Disease Complex (CIRDC) can occur in a dog population. At least nine different bacteria and viruses have been linked as causes of CIRDC, which is transmitted by respiratory droplets. Infection with more than one bacterial or viral agent is common,” they wrote.

“Symptoms include coughing, sneezing, nasal and/or eye discharge, and lethargy. If your dog shows these symptoms, please contact your veterinarian. We encourage you to speak to your veterinarian about what vaccines are appropriate for your dog. These may include canine influenza, Bordetella and parainfluenza.”

The San Diego Humane Society has paused dog surrenders due to cases of what it called “strep zoo.” However, the TODAY Show reported that officials in San Diego don’t believe their outbreak is related to the mysterious illness killing dogs.

The San Diego release reported that “four dogs died from Strep zoo at the organization’s San Diego Campus. Strep zoo is a bacteria that is primarily spread through direct contact and fomites. To prevent the spread of the disease, all dogs at the organization’s San Diego Campus are being treated, and staff working with the dogs are required to wear personal protective equipment.”

Officials Offered Suggestions to Dog Owners

hot weather

Ed Jones/AFP via GettyChildren play with a dog in a water fountain on July 26, 2023 in New York during a heat wave.

“If you have concerns about your dog being present in groups of dogs, such as at an agility event or while boarding, we recommend that you consult with your veterinarian about recommendations for infection prevention and mitigation,” Oregon officials wrote.

They offered these situations for dogs having contact with other dogs:

Make sure all dogs are up-to-date on all their vaccines including canine influenza, Bordetella and parainfluenza.
For event organizers: Dogs should have a health check 12-24 hours before the event. Have a DVM onsite checking dogs for health issues (mild nasal discharge, cough, elevated temperature, being off food).
Please consult with your veterinarian for dog-specific advice before attending any events where dogs are congregated.

According to the Oregon news release, “Periodic outbreaks of Canine Infectious Respiratory Disease Complex (CIRDC) can occur in a dog population and some cases can be serious. Transmitted by respiratory droplets, both viruses and bacteria can cause CIRDC. CIRDC cases more commonly occur in animals housed in settings such as shelters, boarding, or training facilities rather than in animals housed in private homes, especially those with limited access to other dogs.”

They noted: “Veterinarians treat cases according to the dog’s symptoms and severity of symptoms. Treatment may include antibiotics. Most dogs, especially those vaccinated against respiratory illness, experience a mild illness. Symptoms of CIRDC include coughing, sneezing, nasal and/or eye discharge, and lethargy. If your dog shows these symptoms, please check with your veterinarian.”

To protect their dogs, officials recommended dog owners do the following:

Reducing contact with large numbers of unknown dogs. Just like with other respiratory pathogens, the more contacts your dog has, the greater the risk of encountering a dog that’s infectious.
Reducing contact with sick dogs. This can be harder to determine but if a dog looks sick (coughing, runny nose, runny eyes), keep your dog away from it.
Keep sick dogs at home and seek veterinary care.
Avoid communal water bowls shared by multiple dogs.
Ask your veterinarian for advice on which vaccinations your dog should have. Common vaccinations include canine influenza, Bordetella and parainfluenza.
If it’s sick, consider having your dog tested with a PCR test to help determine the causative agent (viral/bacterial), if possible.

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