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. 2020 Mar 20;8:83. doi: 10.3389/fpubh.2020.00083

Table 1.

Overview of major natural influenza A subtype infections and reassortment events reported in dogs and cats.

Influenza A subtypea First isolation (localization and year) Host species (origin) Currently reported geographic distributionb Severity of the diseasec Intraspecies transmissibilityd Transmission to humanse References
CIV-H3N8 Florida, USA, 2004 Dogs (Horse) USAb, UK, Canada + + Never reported (7–9)
CIV-H3N2 China, 2006 Dogs and Cats (Avian) Southeast Asiab, North Americab ++ ++ Never reported (10–16)
LPAIV H7N2 New York City, USA, 2016 Cats (Avian) USA + + Reported once (17, 18)
HPAIV H5N1 Thailand, 2006 Dogs and Cats (Avian) Thailand, China, Austria, Germany + + + –/+ Never reported (19–25)
A(H1N1)pdm09 Italy, 2009 Dogs and Cats (Human) USA, China, Mexico, Italy + + + + Reverse zoonosis (26–34)
CIV-H3N1* South Korea, 2010 Dogs (Human) Unknown - - Never reported (35)
CIV-H3N2* South Korea, 2012 Dogs (Human) Unknown ++ + Never reported (36)
CIV-H1N1r* China, 2015 Dogs (Swine) China ++ Unknown Never reported (37)
CIV-H1N2r* China, 2014 Dogs (Swine) China + Unknown Never reported (37)
CIV-H3N2r* China, 2015 Dogs (Swine) China + Unknown Never reported (37)
a

CIV, Canine Influenza Virus; HPAIV, High Pathogenic Avian Influenza Virus; pdm, pandemic; LPAIV, Low Pathogenic Avian Influenza Virus; r, reassortant and further highlighted by an asterisk.

b

Refers to endemic subtype in canine population.

c

Severity was defined based one the following criteria: + mild respiratory symptoms; ++ severe respiratory symptoms; + + + systemic infection.

d

Intraspecies transmissibilty refers to dog-to-dog and cat-to-cat transmission events and was classified as follows: - no evidence of case-to-case transmission; –/+ limited transmission; ++ efficient spreading.

e

Reverse Zoonosis refers to an influenza subtype that can be transmitted from humans to companion animals.