The following report was composed with information provided by the University of Kentucky Veterinary Diagnostic Laboratory and Equine Diagnostic Solutions, Inc. —both in Lexington, Kentucky, United States of America.
Sick horse during a coughing spell
This report is retrospective and does not claim to be complete; however, it provides an indication of heightened activity of relevant contagious or environment-linked diseases among equids.
© 2017 by S. Hanusch
Furthermore, information from the International Thoroughbred Breeders Federation, International Collating Centre in Newmarket, United Kingdom, and American Association of Equine Practitioners’ Equine Disease Communication Center was included. This report is retrospective and does not claim to be complete. However, it provides an indication of heightened activity of relevant contagious or environment-linked diseases among equids.
To further improve this data, we encourage entities outside the USA to report laboratory-confirmed (toxico) infectious diseases of Equidae to the ICC. Reports from Asia, Africa, South America and Australia were not received for this quarter.
The USA reported rapidly spreading vesicular stomatitis virus infections in various cohorts of horses mainly throughout California with fewer outbreaks reported from Texas (first reported in mid-May 2023). VSV is an arbovirus transmitted by a variety of insects, mainly biting midges and sandflies, but also stable flies. Direct contact and fomites are alternative methods of transmission.
VSV outbreaks typically follow a seasonalpattern from late spring and summer in the USA, and reported outbreaks are typically localized to the Western United States. Typical clinical signs consist of painful blisters followed by ulceration of the oral mucosa. Disease is endemic in the USA and South and Central America.
North America and Europe, including the British Isles, consistently report strangles (caused by Streptococcus equi spp. equi) cases and outbreaks. It is currently the most consistently reported pathogen. In North America, most cases are reported from several distinct regions. Within the USA, Florida, Michigan and Washington frequently report cases, and most cases from Canada are reported from the province of Ontario.
An outbreak of equine influenza virus was traced to a Standardbred racing facility in the province of Quebec, Canada; the outbreak rapidly spread to other (mainly) Standardbred training facilities. On a smaller scale, another outbreak of EI was reported in the U.S. Pacific Northwest. Scattered EI PCR positive nasal swabs were also reported from various U.S. regions, including the Midwest, Southwest and East Coast. EI cases and outbreaks were also reported from central Europe.
Equine herpes virus 4 or 1 respiratory disease was reported infrequently throughout the USA. A higher incidence was reported from operations in the United Kingdom, Ireland and from continental Europe.
Few EHV abortions were reported from North America. Three abortions caused by EHV-1 were diagnosed in central Kentucky. Of note, there has not been further propagation of disease within the pregnant mares on those farms. This is likely due to high vaccine coverage combined with a fast and effective management intervention. EHV-1 abortions typically occur in the last trimester of pregnancy; therefore it is understandable that the number of abortions significantly increased in continental Europe and the British Isles compared to the spring quarterly report.
Equine herpesvirus myeloencephalopathy also follows a seasonal pattern with the majority of outbreaks occurring in the first, second and fourth quarters in the Northern Hemisphere. Localized outbreaks were reported from across the USA and Canada. Single outbreaks were reported from Scandinavia and the British Isles, and two outbreaks were reported from central Europe.
A few scattered equine infectious anemia cases were reported in the USA and Canada. A single report was received from France. Year-round vector activity occurs in regions bordering the Gulf of Mexico.
Four cases of Eastern equine encephalitis were reported in Florida. Although early for the season and quarter, a single case of West Nile virus was identified in the Midwest Region of the USA.
During the quarter, there were 35 positive samples for rotavirus A or B and close to 100 Rhodococcus equi positive samples reported. These numbers were derived mostly from the Lexington, Kentucky, laboratories. While many samples were submitted from within Kentucky, a significant number were from other states. Nine cases of rotavirus and 11 of Rhodococcus were reported from France.
Miscellaneous: Contagious equine metritis: Three reports of Taylorella equigenitalis (the cause of CEM) were reported from Germany. It is currently unknown whether these cases were epidemiologically connected.
Press release by Lutz Goehring University of Kentucky Gluck equine research Center - Department of Veterinary Science.