June 21, 2024

Mysterious Respiratory Illness Sweeping Across Dogs in U.S.

Written by AiBot

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Nov 25, 2023

A mysterious respiratory illness is rapidly spreading among dogs across the United States, causing symptoms like coughing, vomiting and fever and even death in some cases. Though the exact cause remains unknown, researchers are investigating several potential explanations.

Over 150 Cases Reported Across Over 30 States

As of November 2022, over 150 probable cases of the illness have been reported by veterinarians and dog owners across more than 30 states, though the actual number could be much higher. Some of the states that have confirmed cases so far include:

  • California
  • Colorado
  • Connecticut
  • Florida
  • Georgia
  • Illinois
  • Iowa
  • Massachusetts
  • Michigan
  • Minnesota
  • New York
  • North Carolina
  • Ohio
  • Oregon
  • Pennsylvania
  • South Carolina
  • Tennessee
  • Texas
  • Wisconsin

However, many more states could have unreported or undiagnosed cases.

Symptoms Usually Include Coughing, Vomiting, Fevers

The most common symptoms being reported are coughing, vomiting and high fevers of over 104 or 105 degrees Fahrenheit. Some dogs are also exhibiting eye and nasal discharge, lethargy, loss of appetite and shortness of breath.

In severe cases, dogs rapidly deteriorate and die within a few days of showing symptoms. The illness appears to have a mortality rate of around 50%.

Several Theories Under Investigation

Researchers and veterinary experts do not yet know what is causing the illness. Several theories are being investigated:

Canine Influenza

Some evidence suggests this could be a novel or mutated strain of canine influenza. But flu infections do not typically have such a high mortality rate.

Canine Parainfluenza Virus

Another possibility is a hyper-virulent mutation of canine parainfluenza virus, which can cause respiratory infections like kennel cough.

Canine Pneumovirus

In September 2022, a group of researchers published a study detailing a new canine pneumovirus they discovered through metagenomic sequencing of dogs with respiratory illness. This virus could potentially be involved in the current outbreak.


Co-infections of multiple respiratory pathogens like parainfluenza, adenovirus and mycoplasma could also be behind some of the severe cases.

Toxic Exposure

Some veterinary toxicologists hypothesize that the symptoms could represent dogs’ extreme reactions to toxins like mold, pesticides or vaping liquids. However, a toxic exposure would be unlikely to spread as quickly nationwide.

Without a known root cause, treatment options are still extremely limited for dogs exhibiting symptoms.

Advice For Concerned Dog Owners

Veterinarians and health experts recommend concerned dog owners take the following precautions while this illness spreads:

  • Avoid contact with unfamiliar dogs when out on walks or at dog parks.
  • Skip visits to doggie daycares or boarding kennels when possible.
  • Carefully monitor your dog for any respiratory or flu-like symptoms and call your vet immediately if they develop.
  • Stock up on prescription medications your dog regularly takes in case you need to isolate them at home.
  • Have dogs up to date on core vaccinations like parvo, rabies and DHPP to ensure basic immunity.
  • Consider asking your vet about administering canine influenza and kennel cough vaccines, which could provide some level of protection.
  • Be prepared with emergency contacts and know which veterinary hospitals have isolation capabilities if your dog falls severely ill.
  • Follow suggested isolation protocols if your dog develops symptoms, including wiping their paws after going outside, using separate outdoor potty spaces and having one family member provide all their care.

Veterinarians emphasize this situation remains very fluid and unknown. Stay vigilant, but also try not to panic.

Government Agencies Start Investigations

With over 150 probable cases identified across dozens of states in just a matter of weeks, federal agencies are prioritizing the investigation of this significant emerging outbreak.

CDC Alerts Doctors & Vets

On November 18th, the Centers for Disease Control and Prevention (CDC) issued an alert to human medical providers and veterinarians asking them to be on the lookout for this respiratory illness in canines.

The notice provided details on the symptoms seen so far and asked clinicians to report any potential cases in dogs to their state veterinarian or agriculture department.

USDA Consults Lab Partners

The United States Department of Agriculture (USDA) is also consulting with multiple veterinary diagnostic labs and academic partners on this evolving situation. The agency is encouraging vets to submit case samples to these laboratories for analysis and genomic sequencing.

Investigation Expands Globally

Importantly, respiratory illnesses very similar to those in the U.S. have recently been reported among dogs in Canada as well as the U.K. and Australia.

Accordingly, the USDA is now cooperating with partners across North America, Europe and Australia/New Zealand as part of the joint epidemiological investigation.

Researchers Now Racing Against the Clock

Academic teams at several universities are working urgently to try identifying the underlying cause.

UW Scientists Find New Pneumovirus Strain

Scientists at the University of Wisconsin’s School of Veterinary Medicine announced on November 12th they discovered a new strain of canine pneumovirus through metagenomic testing of dogs with this respiratory illness.

This pneumovirus strain is distinct from the one identified in the September study and appears to be contributing to symptoms. However, researchers say it is likely not acting alone.

Cornell Finds Evidence of Multiple Pathogens

A team at Cornell University College of Veterinary Medicine recently posted their findings about an infectious pneumonia also causing illness and death in dogs this fall.

They found evidence of multiple respiratory pathogens circulating simultaneously, including Streptococcus zooepidemicus and distinct strains of canine influenza virus and parainfluenza virus.

Other Teams Studying Environmental Factors

Additional academic groups are researching potential connections to environmental pollutants, toxins or allergens as well as links to geographic location and climate conditions.

With teams urgently working on parallel tracks, hopefully researchers can soon pinpoint either a single infectious culprit or combination of factors driving this mysterious and dangerous outbreak in pets nationwide.

Short & Long Term Outlook Remains Uncertain

It is difficult to predict how long this situation may last or how far illnesses could spread without knowing the root cause. Here is what we may see in both the short and long term:

More Cases & Hospitalizations in Coming Weeks

Over the next few weeks to months, both confirmed case numbers and hospitalizations of dogs with severe pneumonia will likely continue rising across most U.S. states.

With many families traveling and gathering for upcoming holidays, illnesses could spike from increased exposures. Dogs presenting with suspicious respiratory symptoms should be evaluated and treated as potential cases.

Expanded Geography Including Canada & Europe

This outbreak now appears global in scope, with corresponding cases being seen across Canada, the U.K. and Australia. As international travel picks up, we may find this illness distributing to dogs in more areas outside the U.S.

Accordingly, veterinary diagnostic labs across North America and Europe will need to stay highly vigilant for potential infections in local canine populations.

Eventual Identification of Causative Agents

Most experts remain confident researchers will ultimately pinpoint either a singular infectious pathogen or combination of factors driving the outbreak.

Successfully identifying contributing viruses would allow creation of new targeted tests and treatments to manage this evolving contagious threat.

Potential Long Term Circulation

However, even once solved, if the responsible agent or agents demonstrate sustained rapid transmission between dogs, versions of this respiratory illness could continue circulating indefinitely within canine populations.

In that case, this emerging outbreak might represent establishment of an important new endemic canine disease necessitating long term vigilance and control measures.

Key References: Outbreak Maps & Guidance

Canine Respiratory Illness Cases By State

The following map from Newsweek displays the latest states with confirmed and suspected cases:

Map of states with reported cases

Advice For Concerned Dog Owners

This article from the American Veterinary Medical Association covers key guidance for protecting pets:

Mysterious respiratory disease alert: What veterinarians want owners to know

Investigation Updates From Cornell University

Cornell Vet’s Infectious Diseases Lab posts frequent updates on their latest findings:

What we know about canine pneumonia cases

Conclusion: Vigilance Needed Amid Unfolding Outbreak

This swiftly expanding outbreak of canine respiratory illness in the U.S. remains extremely concerning and volatile. With researchers racing to uncover answers, veterinarians, government agencies and dog owners nationwide will need to stay alert and vigilant in the weeks and months ahead.

Though this situation sparks worry, try to remain calm and follow science-based guidance when protecting and caring for your pets. With patience and persistence, experts are hopeful solutions can be found to properly diagnose, manage and eventually control what could become an established canine disease threat.




AiBot scans breaking news and distills multiple news articles into a concise, easy-to-understand summary which reads just like a news story, saving users time while keeping them well-informed.

To err is human, but AI does it too. Whilst factual data is used in the production of these articles, the content is written entirely by AI. Double check any facts you intend to rely on with another source.

By AiBot

AiBot scans breaking news and distills multiple news articles into a concise, easy-to-understand summary which reads just like a news story, saving users time while keeping them well-informed.

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