Atypical Canine Infectious Respiratory Disease (aCIRD) emerged in late summer 2023, presenting longer symptom duration (6-8 weeks vs. typical kennel cough) and progression to pneumonia in some cases. Dogs test negative on standard respiratory PCR panels (Bordetella, parainfluenza, adenovirus, influenza).
New Research (AJVR, July 2025)
A retrospective study of 415 US cases identified prognostic factors practitioners should monitor.
Geographic variation:
- Highest case rates: Southeast (26.3%)
- Highest case fatality: Southwest (17.9%)
- Lowest fatality: Northeast (6.7%)
Age distribution: Dogs under 5 years most affected across all regions (41-57%)
Critical finding — Poor prognosis indicators: Dogs presenting with lethargy, fever, difficult breathing, AND sneezing had 8× higher odds of death compared to those with a broader symptom mix (coughing, vomiting, nasal discharge).
Treatment patterns: Doxycycline most commonly used (31-50%), though antibiotic effectiveness has been limited.
Practical Guidance
- Isolate symptomatic dogs 28+ days (longer than standard kennel cough protocols)
- Monitor for the high-risk combination: lethargy + fever + dyspnea + sneezing
- Vaccination helps reduce severity but doesn’t prevent aCIRD (keep Bordetella, parainfluenza, H3N2, distemper current)
- Advise clients to avoid dog parks, boarding, daycare with sick or recently sick dogs
Current Status
Case numbers have receded from the 2023-2024 peak, but aCIRD remains a diagnostic challenge. The causative pathogen is still unidentified. Practitioners should maintain vigilance, especially during boarding/daycare season.
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References
- Hasan M, Romano TA, Miller LC. Characteristics and case fatality factors of atypical canine infectious respiratory disease: an observational survey using dog owners’ data in the United States. Am J Vet Res. 2025;86(10). doi:10.2460/ajvr.25.04.0133
- Los Angeles County Department of Public Health, Veterinary Public Health Program. Atypical Canine Infectious Respiratory Disease (aCIRD) Advisory.