Epidemiology and ecology of H3N8 canine influenza viruses in US shelter dogs.

BACKGROUND: H3N8 canine influenza virus (CIV) infection might contribute to increased duration of shelter stay for dogs. Greater understanding of factors contributing to CIV within shelters could help veterinarians identify control measures for CIV. OBJECTIVES: To assess community to shelter dog CIV transmission, estimate true prevalence of CIV, and determine risk factors associated with CIV in humane shelters. ANIMALS: 5,160 dogs upon intake or discharge from 6 US humane shelters, December 2009 through January 2012. METHODS: A cross-sectional study was performed with prospective convenience sampling of 40 dogs from each shelter monthly. Nasal swabs and serum samples were collected. Hemagglutination inhibition and real-time reverse transcriptase-polymerase chain reaction assays were performed for each nasal and serum sample. True prevalence was estimated by stochastic latent class analysis. Logistic regression was used to identify risk factors associated with CIV shedding and seropositivity. RESULTS: Nasal swabs were positive from 4.4% of New York (NY), 4.7% of Colorado (CO), 3.2% of South Carolina, 1.2% of Florida, and 0% of California and Texas shelter dogs sampled. Seropositivity was the highest in the CO shelter dogs at 10%, and NY at 8.5%. Other shelters had 0% seropositivity. Information-theoretic analyses suggested that CIV shedding was associated with region, month, and year (model weight = 0.95) and comingling/cohousing (model weight = 0.92). CONCLUSIONS AND CLINICAL IMPORTANCE: Community dogs are a likely source of CIV introduction into humane shelters and once CIV has become established, dog-to-dog transmission maintains the virus within a shelter.

Seroprevalence and risk factors for canine H3N8 influenza virus exposure in household dogs in Colorado.

BACKGROUND: Since 2004, canine influenza virus (CIV) has spread throughout the United States. While studies suggest that CIV is commonly detected in shelter dogs, little is known about its prevalence in household dogs. OBJECTIVES: To evaluate the seroprevalence of CIV in pet dogs presented for care in a veterinary hospital in Colorado and to investigate risk factors that might predispose these dogs to CIV infection. ANIMALS: One hundred and forty dogs presenting to the Community Practice service, 110 dogs seen at other clinical services at Colorado State University's Veterinary Teaching Hospital in 2009, and samples from 75 dogs seen before 2004. METHODS: In this prospective study, samples were tested with hemagglutination inhibition assays, using 3 CIV isolates. To identify risk factors for CIV infection, 140 owners completed questionnaires at time of sampling. RESULTS: CIV seroprevalence was 2.9% (4/140) for dogs seen by the Community Practice service and 4.5% (5/110) for dogs seen by other hospital services (P=.48). All sera collected before 2004 tested negative for CIV. No differences were seen in antibody titers to the 3 CIV isolates tested. Data from the questionnaires indicated an association between CIV seropositivity and canine daycare visits (P<.001). CONCLUSION AND CLINICAL IMPORTANCE: CIV seropositivity in household dogs in Colorado is low, although it has increased since 2004. Antibody titers to the 3 CIV isolates were comparable, suggesting that measurable antigenic drift has not yet occurred. Finally, dogs boarded in kennels or attending daycare might be at an increased risk of CIV infection.

Detection and management of an outbreak of equine herpesvirus type 1 infection and associated neurological disease in a veterinary teaching hospital.

BACKGROUND: Because of the serious disease sequelae associated with equine herpesvirus type 1 (EHV-1) infections, awareness and control measures used to control outbreaks are important issues for all horse populations. OBJECTIVES: Describe the occurrence and management of an outbreak of EHV-1 infection at a veterinary hospital. ANIMALS: Horses hospitalized at a referral veterinary hospital. METHODS: A horse with myeloencephalopathy associated with EHV-1 infection (EHM) was admitted for diagnostic evaluation and treatment under strict infection control procedures. We describe the occurrence and management of a nosocomial outbreak of EHV-1 infections associated with admission of this patient. RESULTS: Despite institution of rigorous biosecurity precautions at the time of admission of the index case, EHV-1 infections spread to 6 other horses that were hospitalized at the James L. Voss Veterinary Teaching Hopsital, including 2 that served as sources of infection for horses on their home premises after discharge. Infection with EHV-1 was confirmed by polymerase chain reaction (PCR) and by seroconversion documented by glycoprotein G ELISA. A voluntary quarantine was imposed and admissions were restricted to prevent additional horses from being exposed. Quarantine duration was abbreviated by serial testing of all horses with PCR. CONCLUSIONS AND CLINICAL IMPORTANCE: These findings illustrate the contagious disease risk that can accompany management of horses with EHM. Horses with active nasal EHV-1 shedding should be isolated in an airspace that is separate from other horses by strictly enforced biosecurity and isolation procedures. Serial testing with PCR may be a useful adjunct to determine when the risk of transmission has been minimized.