Canine Respiratory Disease

(November 22, 2023) The Colorado Department of Agriculture (CDA) has been receiving calls over the past two months from practicing veterinarians reporting an elevated number of canine respiratory disease cases in the state.  Other states, including Oregon, Florida, and New Hampshire, are seeing a similar pattern at this time.  

Veterinarians are currently reporting that they are seeing double the number of cases than what is typically seen during a canine infectious respiratory disease outbreak. The cases are presenting with prolonged coughing which can last weeks to months with minimal response to treatment. In some cases, the dogs have progressed to contracting pneumonia and require hospitalization.  In rare cases, the canine patients progress quickly from pneumonia to death.

Some diagnostics have been completed, but there has not been any conclusive testing to indicate what may be causing the increased prevalence of this respiratory disease.  This does not necessarily mean this is a new or novel virus as there are many causes for canine respiratory infections, but we are working on additional diagnostics at this time.  

CDA is currently working with partners from Colorado State University (CSU) Veterinary Teaching Hospital (VTH) and Veterinary Diagnostic Laboratory (VDL), Colorado Department of Public Health and Environment (CDPHE), the United States Department of Agriculture (USDA), and the Colorado Veterinary Medical Association (CVMA) to coordinate on the situation.  

This website will be updated as we learn additional information, so please check back frequently.

For media inquiries, please send your email to cda_info@state.co.us.  

Update: November 29, 2023

The Colorado State University has continued to test samples and have found several positive cases on routine diagnostic tests, including parainfluenza, canine coronavirus, and pneumovirus.  We have yet to identify a single causative agent to tie these cases together.  CSSU and CDA will continue to work with private practitioners to enhance diagnostic testing in Colorado, especially for acute cases.

We are aware of the University of New Hampshire's recent pathogen findings in the canine respiratory outbreak.  As mentioned in their press release, they are unsure of the significance of this finding at this time or if that is the causative agent in this widespread outbreak.

The CSU Veterinary Diagnostic Laboratory is actively studying the syndrome and providing weekly updates on their website.

Update 2/14/24

Based on data provided by Trupanion, the increase in canine respiratory cases has significantly decreased from the numbers seen in the last couple of months of 2023.  Canine respiratory disease trends indicate this is part of the cycle that this category of disease follows.
Since risk is never zero, it is still important to manage vaccines and lifestyles appropriately.
We encourage the public to discuss with their veterinarians the best practices for each animal, especially dogs in high social situations, who have compromised immune systems, and older animals as they are in the highest risk category for developing clinical disease. Owners should talk with their veterinarian about continuing vaccinations for respiratory disease on a yearly basis.
For more information on the Canine Respiratory Disease Outbreak update please see the webinar from Trupanion.


Black lab in canine respiratory disease warning

Information for Pet Owners


Outbreaks of canine infectious respiratory disease are not uncommon and happen from time-to-time in the dog population. There are a number of different pathogens that can cause respiratory disease in dogs that are primarily transmitted through the air by respiratory droplets when dogs breathe and especially when they cough.

Symptoms can include coughing, difficulty breathing, sneezing, nasal and/or eye discharge, and lethargy.  

Here are a few things you can do to protect your pet:

  • Ensure dogs are up-to-date on vaccinations, including canine influenza, bordetella and parainfluenza.
  • Reduce your pet’s exposure by limiting commingling with other dogs outside the home (including dog parks, boarding, grooming, and play groups).
  • Consult with your veterinarian if your dog becomes ill. Early diagnostics may help in getting an accurate diagnosis and treatment. If your dog becomes ill or presents symptoms, keep them at home to avoid exposure to other dogs.  

Dog owners should contact their veterinarian with additional questions or for more information.

CDPHE monitors certain respiratory illnesses in humans, such as RSV, influenza, and COVID-19, and has not linked any reported human respiratory illnesses to ill dogs at this time. 

Any person who develops signs of respiratory illness who had close contact with an ill dog should consult with their physician as they normally would during the winter season. 

Information for Veterinarians


We have not yet been successful in determining a single causative agent in this outbreak, though that may be due to lack of testing or testing too late in the course of disease. In general, there is a limited timeframe that viruses are shed in the respiratory tract, so acute diagnostics are important. Ideal testing for suspected viral infection would be within the first 72 hours of onset of clinical signs and prior to initiating therapy. 

CDA is currently working with USDA and CSU to determine what additional support may be available for veterinarians to conduct diagnostic workups on these respiratory cases. 


Diagnostic Testing Information

  • Veterinarians should contact their vaccine providers to inquire about disease monitoring programs. These companies may provide diagnostic testing support for vaccinated animals. 
  • If you are submitting samples, please contact your referral laboratory for appropriate sample collection and storage. 
  • Here are some basic guidelines from CSU regarding sample collection for acute respiratory cases: 
    • Collect nasal and oropharyngeal swabs for PCR testing using appropriate swabs and viral transport media. 
    • Do NOT use cotton-tipped, wooden shafted swabs as they contain PCR inhibitors. 
    • In cases of pneumonia, respiratory washes can be collected for culture to aid in treatment of infections that have an opportunistic bacterial component. 
  • If you are doing in-house diagnostics or using a referral lab other than CSU, consider collecting duplicate samples. Hold the second set of samples until the screening tests are completed. 
    • If the initial screening tests come back negative, we are working on a process to submit those samples to CSU, along with an epidemiology questionnaire, for additional diagnostic workup utilizing USDA’s Unusual Morbidity/Mortality Event funding. This additional testing is specifically for acute case work-ups. We will update this website when that process is finalized. 


Diagnostic Resources


Veterinary Case Management

Most of these cases are currently being managed with supportive therapy and empirical treatment. Veterinarians should refer to the International Society for Companion Animal Infectious Diseases guidance document for managing respiratory infections.

Pet owners should contact their veterinarian directly with questions or concerns. Veterinarians may contact the State Veterinarian’s Office at 303-869-9130. 

Canine Events and Facilities


  • Ensure dogs entering the event or facility are healthy and do not present with symptoms such as coughing, sneezing, eye/nasal discharge, or lethargy. 
  • Consult with a veterinarian on best practices for your event or facility.  
  • Monitor dogs for symptoms of respiratory illness (including coughing, fever, nasal/eye discharge, and lethargy).  
  • Have a plan in place to isolate or remove sick dogs from the event or facility. 

Resources for event organizers and facility operators:

USDA Cleaning and Disinfection Guidance Document
ASPCA Shelter Care Checklist
ASPCA Cleaning and Disinfecting Transport Vehicles and Crates