Canine Influenza

Abstract

In 2004, the isolation of an influenza virus from racing greyhounds changed the point of reference for discussions about influenza virus in dogs. A virus isolated from greyhounds did not have its origin in a previously described human influenza virus but came from a virus with an equine history. More significantly, evidence emerged to indicate that the virus was capable of transmission from dog to dog. This virus is now referred to as canine influenza virus (CIV) and is the focus of this review. Because the history of CIV is relatively short, the impact of this virus on canine health is yet to be determined.

Diagnostic Application of H3N8-Specific Equine Influenza Real-Time Reverse Transcription Polymerase Chain Reaction Assays for the Detection of Canine Influenza Virus in Clinical Specimens

“…Detection of CIV is frequently attempted by traditional virus isolation (VI) in embryonated hens' eggs or in Madin-Darby canine kidney (MDCK) cells. 4 There have been some conflicting reports over the sensitivity of antigen-capture enzyme-linked immunosorbent assays for the detection of CIV in dogs. 4,15 Presence of CIV nucleic acid in clinical specimens has been confirmed by traditional reverse transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR assays targeting the matrix (M) gene of Avian influenza virus or by an real-time RT-PCR assay specific for the H3 HA or the M gene of CIV.…”

“…2,4 Sequence analysis of Canine influenza virus (CIV) from the original outbreak (A/canine/FL/43/04) revealed that 8 gene segments of this virus shared $96% nucleotide sequence homology with that of the H3N8 EIV subtype, suggesting that CIV resulted from direct interspecies transmission of EIV to dogs without genetic reassortment. 2,11 The sequence changes in the hemagglutinin gene (H3 HA) are indicative of adaptive evolution of the virus in its new host.…”

“…2,11,18 Most outbreaks of CI occur in rescued, kenneled, or boarded dogs. 4 Clinical signs of the disease include low-grade fever, lethargy, anorexia, nasal discharge, and prolonged cough. 4,11 These signs can mimic those caused by other canine respiratory pathogens.…”

“…4 Clinical signs of the disease include low-grade fever, lethargy, anorexia, nasal discharge, and prolonged cough. 4,11 These signs can mimic those caused by other canine respiratory pathogens. Accordingly, it is especially important to be able to distinguish CIV from other agents capable of causing canine respiratory disease.…”

“…Accordingly, it is especially important to be able to distinguish CIV from other agents capable of causing canine respiratory disease. 4 Detection of CIV at the early stage of infection is especially important for facilitating management and control of the disease. To date, few publications have described specific diagnostic assays to detect CIV in clinical specimens.…”