For veterinarians: Information about mysterious respiratory illness in dogs

Recent media coverage of a “mysterious” respiratory illness in dogs in the US has created concern with dog owners and veterinarians.  While there is always a year-round baseline incidence of dogs with a respiratory infection, spikes in number of affected dogs occur periodically during a typical year. At this time, it is clear that spikes are occurring in some locations, but what is not clear is whether the current surge in numbers is part of the expected cycle, whether it is truly much larger than expected, or whether media coverage has amplified the situation. For example, dogs with mild respiratory illness might not be taken to a veterinarian under normal circumstances. However, if the owner is very concerned because of recent news coverage, they might be more likely to take their dog to a veterinarian now versus in previous years.  

The cause(s) of the infections have not been determined by routine testing to date, leading to speculation that the current infection spike is caused by a new “mysterious” pathogen. While this potential is being investigated, it is also possible that the illness is due to viruses and bacteria known to cause respiratory infections in dogs. The current disease patterns don’t clearly fit with emergence of a new highly transmissible pathogen. The answers await the testing of many more samples that are being submitted to diagnostic labs by veterinarians at this time.

We understand that veterinarians may be seeing more sick dogs than they normally do, some of whom have an acute pneumonia that appears refractory to antibiotic therapy.  Many respiratory pathogens are highly contagious viruses with potential for causing acute pneumonia that does not respond to antibiotics, most notably canine pneumovirus and H3N2 canine influenza virus.  Streptococcus zooepidemicus is an emerging bacterial pathogen causing acute pneumonia that can rapidly progress to death. These dogs will respond to appropriate antibiotic therapy if started quickly. Regardless of the cause, the vast majority of dogs with a respiratory infection recover in a week or two without any complications.

What should veterinarians do? 

1. Know the Risk Factors for Exposure to Respiratory Pathogens

Many of the dogs with respiratory infections have a history of recent contact with other dogs in a social setting.  These settings include exposure to unfamiliar dogs and dogs with unknown health status. Respiratory viruses and bacteria are highly contagious and spread through the air as well as by direct contact with contaminated surfaces and objects in the environment. These transmission properties result in spread between dogs co-housed in a kennel setting or in direct contact with other dogs. Such settings include:

  • Boarding kennels
  • Daycare centers
  • Dog parks
  • Groomers
  • Dog shows

2. Take Precautions to Protect Your Practice

  • Establish a policy for arranging appointments to see dogs with acute onset of respiratory infection outside of the clinic. This mitigates risk for dogs bringing in highly contagious pathogens that can spread to other dogs in the clinic.
  • Receptionists should ask clients when the illness started and if the dog has been with other dogs in a public setting within the past week. The clients are instructed to call the clinic when they arrive and stay in the car with their dog. Clients should understand not to bring the dog into the lobby.
  • The medical team should wear PPE when assessing the dog outside.
  • If available, the dog can be escorted to an isolation room through a separate entrance from that used for other dogs.
  • Collect oropharyngeal and nasal swabs from dogs that have been sick for <4 days or those with acute onset of pneumonia and submit to a diagnostic lab that offers a comprehensive respiratory pathogen PCR panel including canine pneumovirus, influenza A virus, H3N2 canine influenza virus, and Streptococcus zoopepidemicus. Diagnosis of canine pneumovirus, H3N2 canine influenza virus, or Streptococcus zooepidemicus impacts patient management.
  • Dogs with pneumonia requiring hospitalization should ideally be treated in an isolation room by staff wearing PPE because these dogs might be contagious.

3. Treatment Guidelines

  • Most dogs experience mild disease, with coughing, sneezing, and clear nasal discharge, but are otherwise still active and eating and can be treated as an outpatient. Antibiotics are not warranted unless there is mucopurulent nasal discharge.  Instruct owners to keep the dog isolated at home from other dogs for 14 days (21 days if H3N2 canine influenza), and advise owners on the signs to monitor for, should disease progression occur. Dogs with pneumovirus or H3N2 canine flu are more prone to progressing to pneumonia.
  • For dogs with fever, inappetence, and mucopurulent discharges, consider treatment with doxycycline or amoxicillin-clavulanic acid for 5 to 7 days. If Streptococcus zooepidemicus is suspected, start treatment with a cephalosporin such as cephalexin or cefpodoxime (Simplicef) or amoxicillin clavulanic acid since many strains are resistant to doxycycline and some fluoroquinolones.
  • For dogs with pneumonia, download the Firstline App for Antimicrobial Use Guidelines for evidence-based recommendations for antimicrobial treatment.

Consult a specialist near you or consult with the UF Small Animal Hospital for complicated cases.

Information for pet owners can be found here.

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