Canine flu 2

UNEXPLAINED DEATHS, CANINES – USA (MULTISTATE)(04)
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Recurrent outbreaks of severe respiratory disease characterized by coughing and fever have occurred in greyhounds at racing kennels in the U.S. in recent years. In January 2004, a typical outbreak occurred in 22 racing greyhounds in Jacksonville, Florida. Most of these dogs had fevers and cough, but 8 died from hemorrhagic pneumonia. I

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Date: 24 May 2005
From: Julie Levy
LevyJ@mail.vetmed.ufl.edu

Dr. Crawford will be presenting a poster on outbreaks of the newly recognized canine influenza virus at next week’s ACVIM meeting in Baltimore. Here is the abstract:
Influenza Virus Infection in Racing Greyhounds
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Cynda Crawford1; Paul Gibbs1; William Castleman1; Richard Hill1; Ed
Dubovi2; Ruben Donis3; Iain Stephenson3; Cathy Smith3; Jackie Katz3
1University of Florida, Gainesville, FL; 2Cornell University, Ithaca,
NY; 3Centers for Disease Control and Prevention, Atlanta, GA

Recurrent outbreaks of severe respiratory disease characterized by coughing and fever have occurred in greyhounds at racing kennels in the U.S. in recent years. In January 2004, a typical outbreak occurred in 22 racing greyhounds in Jacksonville, Florida. Most of these dogs had fevers and cough, but 8 died from hemorrhagic pneumonia. In June 2004, a similar outbreak occurred in thousands of greyhounds at race tracks in 6 states. There are no reports documenting the cause of these acute respiratory disease outbreaks in racing greyhounds. The objective of this work was to identify the etiological agent(s) involved in the January and June 2004 outbreaks.

Paired acute and convalescent nasal swabs and serum samples were collected from dogs with clinical signs and from asymptomatic dogs housed in contact with sick dogs. Bacterial cultures were performed with the nasal swabs. Virus neutralization and hemagglutination assays were performed on serum. Postmortem examinations were conducted on dogs that died during the outbreaks. Bacterial cultures, virus isolation studies, and immunohistochemistry assays for viral antigens were performed with respiratory tract tissues.

None of the common canine respiratory pathogens, including _Bordetella bronchiseptica_, distemper virus, adenovirus type 2, and parainfluenza virus, were identified as the etiological agent(s). Pathologic findings included: 1) severe pulmonary and pleural
hemorrhage; 2) acute to subacute erosive to hyperplastic tracheitis, bronchitis, and bronchiolitis; and 3) bronchopneumonia. The
epithelial lining and airway lumens in these tissues were infiltrated by neutrophils and macrophages.

Influenza A subtype H3N8 virus was isolated from the lungs of a Florida dog that died in January and a Texas dog that died in June. Influenza H3N8 virus was recovered from archived lung tissue from a Florida greyhound that died during a respiratory disease outbreak in 2003. Genetic sequence analyses and phylogenetic comparisons determined that all 3 canine isolates were closely related and have evolved from contemporary strains of equine influenza H3N8. Immunohistochemistry demonstrated influenza antigen in bronchial gland epithelial cells, bronchial and bronchiolar epithelial cells, and in alveolar macrophages. Seroconversion to the canine influenza virus was demonstrated by hemagglutination inhibition and microneutralization assays.

Based on virus isolation from lungs, viral antigens in lung tissues, and seroconversion data, we conclude that the novel canine influenza virus was the etiological agent responsible for the January and June 2004 respiratory disease outbreaks in racing greyhounds. This represents the 1st report of influenza virus associated with respiratory disease in dogs.
–Julie Levy, DVM, PhD, ACVIM
College of Veterinary Medicine
2015 SW 16th Avenue 100126
University of Florida
Gainesville, FL 32608
levyj@mail.vetmed.ufl.edu<