Title: Atypical canine infectious respiratory disease complex

'''Atypical canine infectious respiratory disease complex''' ('''aCIRDC''') is a proposed novel respiratory disease in dogs&lt;ref name=mahamudul&gt;Hasan, Mahamudul and Miller, Laura, Canine Infectious Respiratory Disease Complex: A Case Study of Epidemiology and Risk Factor Investigation Based on Survey Data from Dog Owners Across the United States of America. Available at SSRN: https://ssrn.com/abstract=4805779 or http://dx.doi.org/10.2139/ssrn.4805779&lt;/ref&gt;&lt;ref&gt;Hasan, M., Romano, T. A., &amp; Miller, L. C. (2025). Characteristics and case fatality factors of atypical canine infectious respiratory disease: an observational survey using dog owners’ data in the United States. American Journal of Veterinary Research, 86(10), ajvr.25.04.0133. Retrieved Nov 27, 2025, {{doi|10.2460/ajvr.25.04.0133}}&lt;/ref&gt; of unknown cause. It has been recorded in 19 US states, with more cases on the West Coast.{{cn|date=October 2024}}

It has also been referred to as respiratory syndrome of unknown aetiology in dogs and as canine respiratory disease of unknown origin.&lt;ref&gt;{{cite web | url=https://www.vet.cornell.edu/departments/riney-canine-health-center/canine-health-information/canine-respiratory-disease-outbreaks | title=Canine respiratory disease outbreaks | date=25 August 2022 }}&lt;/ref&gt;

==History==
It was first described in summer 2023 as a cluster of 200 cases around Portland, Oregon.&lt;ref&gt;{{cite web | url=https://publichealth.jhu.edu/2023/understanding-atypical-canine-respiratory-disease | title=Understanding Atypical Canine Respiratory Disease &amp;#124; Johns Hopkins &amp;#124; Bloomberg School of Public Health | date=5 December 2023 }}&lt;/ref&gt;

==Characteristics==
Symptoms include a cough, fever, lethargy, sneezing and watery eyes. In some cases, the illness proceeds to death.&lt;ref name=mahamudul /&gt; Cases tend to fit three clinical syndromes: chronic mild/moderate [[tracheobronchitis]] of prolonged duration (6+ weeks),&lt;ref&gt;{{cite web | url=https://www.cbsnews.com/news/dogs-respiratory-illness-map-acirdc/ | title=Map shows where mysterious dog respiratory illness has spread in U.S. - CBS News | website=[[CBS News]] | date=19 December 2023 }}&lt;/ref&gt; with coughing, sneezing, and watery eyes; chronic pneumonia that is minimally responsive to antimicrobials, possibly including dyspnea; and, rarely, acute pneumonia that rapidly becomes severe and can lead to death.&lt;ref name=lsu&gt;{{cite web | url=https://www.lsu.edu/vetmed/news/2023/canine_respiratory_disease.php | title=LSU Vet Med raises awareness about Atypical Canine Infectious Respiratory Disease Complex (ACIRDC): Symptoms, Research, and Precautions }}&lt;/ref&gt;&lt;ref name=aaha&gt;https://www.aaha.org/publications/newstat/articles/2023-12/canine-respiratory-mystery-what-we-know-about-the-outbreak/&lt;/ref&gt; Most cases are self-limiting and respond well to supportive care.&lt;ref&gt;{{cite web | url=https://news.virginia.edu/content/qa-what-know-about-mysterious-dog-illness-sweeping-country | title=Q&amp;A: What to Know About a Mysterious Dog Illness Sweeping the Country | date=20 December 2023 }}&lt;/ref&gt; Antibiotics may be indicated.&lt;ref name=aaha /&gt;

Diagnosis should rule out known forms of [[canine infectious respiratory disease complex]] (CIRDC; also known as kennel cough). aCIRDC does not respond to regular treatment protocols for CIRCD and the course of the disease is longer and more severe.&lt;ref&gt;{{cite web | url=https://www.vet.cornell.edu/departments/riney-canine-health-center/canine-health-information/canine-respiratory-disease-outbreaks | title=Canine respiratory disease outbreaks | date=25 August 2022 }}&lt;/ref&gt;

There is no evidence that it can spread to humans.{{cn|date=October 2024}}

==Cause==
The cause is currently unknown.{{cn|date=October 2024}}

The Veterinary Diagnostic Laboratory at the University of New Hampshire have put forth a possible bacterium as the cause.&lt;ref name=lsu /&gt; They have tentatively identified this as [[IOLA KY405]],&lt;ref name=unh&gt;https://assets-002.noviams.com/novi-file-uploads/mvma/pdfs-and-documents/Regulatory/K9_Atypical_Pneumonia_Update_V2.pdf {{Bare URL PDF|date=August 2025}}&lt;/ref&gt; which was previously identified in humans in 2021.&lt;ref&gt;{{cite journal | doi=10.1038/s42003-021-02162-6 | title=A human respiratory tract-associated bacterium with an extremely small genome | date=2021 | last1=Fukuda | first1=Kazumasa | last2=Yamasaki | first2=Kei | last3=Ogura | first3=Yoshitoshi | last4=Kawanami | first4=Toshinori | last5=Ikegami | first5=Hiroaki | last6=Noguchi | first6=Shingo | last7=Akata | first7=Kentarou | last8=Katsura | first8=Keisuke | last9=Yatera | first9=Kazuhiro | last10=Mukae | first10=Hiroshi | last11=Hayashi | first11=Tetsuya | last12=Taniguchi | first12=Hatsumi | journal=Communications Biology | volume=4 | issue=1 | page=628 | pmid=34040152 | pmc=8155191 }}&lt;/ref&gt; This is similar to ''[[Mycoplasma]]'' in lacking a [[cell wall]] and having a small genome.&lt;ref name=unh /&gt;

However, other vets have suggested that this might just represent a peak in CIRDC cases and not involve any new pathogens. This could be due to changes in human behaviour following the end of COVID-19 lockdowns and other COVID-19-related disruption to veterinary care (''e.g.'' frequency of vaccination), as well as to the general increase in dog numbers in the US.&lt;ref&gt;{{cite web | url=https://www.vet.upenn.edu/about/news-room/news-stories/news-story-detail/three-takeaways-on-respiratory-illness-in-dogs | title=Penn Vet &amp;#124; Three takeaways on respiratory illness in dogs }}&lt;/ref&gt;&lt;ref name=aaha /&gt;

==See also==
* [[2022 hepatitis of unknown origin in children]]

==References==
{{reflist}}

[[Category:Dog diseases]]
[[Category:Respiratory diseases]]
[[Category:2023 disease outbreaks]]